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mustanggt
12-13-2010, 02:06 AM
I'm at my wits end with my casting. I have been doing really well with my casting, no issues to deal with till now. I have a BACO Creedmoor mould that cast excellent boolits till now. Also a new BACO Money boolit. No matter how hot the melt or mould 700-800, the bases don't fill out and are wrinkled. Melt is 20-1 clean alloy from rotometals, I've fluxed and fluxed and fluxed, cleaned and cleaned and cleaned the moulds, pot ladle. I changed out the alloy and still am having the problem. I preheat the moulds on a hot plate. I gave up after two hours yesterday and two hours today. When the pot cooled it looked like the desert after a rain and it has all dried up and had holes and fissures running through it, not the smooth surface I've always gotten. I decided to move on to another pot and a lyman 44 mould and an rcbs 357 mould. I had problems there too. I was casting along happy to finally get something for my efforts and all of a sudden one of the cavities in the rcbs mould the bases wouldn't fill out either. Front cavity made beautiful bullets as usual as well as the back one then all of a sudden the back one wouldn't fill out to save my butt. I'm doing everything like I always do the only variable is the Money bullet and I can't see that being the problem. The only thing I can think of is I accidently touched the ladle to a towel not made of cotton and some of it melted on it so naturally I cleaned it real well even sanding it as it left some residue on it that took some elbow grease. Could it have been the culprit? By the way I only ladle the big bullets from one pot and bottom pour the rest from another pot. Hope I gave enough info. Thanks

JIMinPHX
12-13-2010, 02:23 AM
What do you lube your mold with & how much do you use?

chris in va
12-13-2010, 02:47 AM
I like to approach problems by elimination.

Think back to what point everything changed. What did you do differently? Alloy, mold, procedures the same?

Might be that towel melting to the ladle, or something else the other guys can suggest. I've only been using Lee molds, but every time I get wrinkles, it's because the mold isn't up to temp. Even if my WW alloy is on the cool side, it still makes great boolits.

Harter66
12-13-2010, 12:15 PM
I've been afraid to try to pour. Our temps have been all over 1 day last week was 22/36 today is to be 40/61.

I've had my own run of bad luck/joo joo/karma(?)of late myself.

I'd bet its the outside temps giving you fits,or different air movement around your work area. Both would give you cold spots it happeneds to me every time we get a due east low instead of the usual from northwest to southeast . The wind blows from the wrong way and the air swirls right up under my pot and across my molds its a pia to keep it all hot. I'd even be suspect of a cold window if your outside temps are more than say 55* colder than inside. Even w/double pains.

My .02.

home in oz
12-13-2010, 12:45 PM
sounds too cold

Rocky Raab
12-13-2010, 01:03 PM
Always keep your joo-joo in a cool dry place, out of direct sunlight.



(Sorry. I couldn't resist.)

JSnover
12-13-2010, 01:07 PM
700-800 is minimal for me (45-70, 500gr). I get better results at 800-900.

onondaga
12-13-2010, 01:08 PM
I can give you some tips that should help, but in general, I find that people who heat bullet alloys to 800 degrees for any reason just don't get it or are too stubborn to believe they could possibly be incorrect. First, if you are casting outdoors or in an unheated area where the temperature is near freezing or lower, wait till a much warmer day.

If you brought your alloy up to 800 and didn't immediately bring it down a couple hundred degrees and re- flux the tin back into the alloy, you ruined your alloy unless you wanted to cast with no tin in it. The tin will stay on the top of overheated alloy and continually oxidize at a rapid rate.. The popular sawdust on top of your melt does nothing to keep the tin in your alloy unless you first have the metal at a temp that does not separate the tin from your alloy and you have properly fluxed the alloy below the separation temperature of tin.

Alloys with no tin don't fill out molds very well even if casting technique is perfect. If you have to use your no tin alloy you will need to do something to vent your mold a lot more than the manufacturer normally does and you might get it to work. That could involve loosening your sprue plate or beveling the top of your mold blocks a few thousands of an inch so they form a small V channel at the top to let air out under a tight sprue plate. Pressure casting may help, ladle casting may help. bottom pour casting will be difficult with that alloy unless your pour spout is immaculate and slightly enlarged and you use the maximum flow rate with a full pot.

You could fix your alloy by adding 2 -3 % tin and fluxing at a temp that does not separate the tin from it. Tin lowers the temperature needed to melt bullet alloys and increases the flow quality of the alloy.Learn how to cast at more moderate temperatures with tin in your alloy and try to isolate your problems one at a time instead of cranking up the temperatures to extremes. 675 degrees is a reasonable maximum. If that doesn't work for you something else is very wrong.

Excellent casting is an harmonious balance of metallurgy, thermodynamics and physics. Pushing one aspect of those three aspects of balance to get acceptable bullets is only getting acceptable bullets, not excellent bullets.

Gary

mdi
12-13-2010, 01:09 PM
Walk away for a day or two. Then start from the beginning. Clean the mold as if it were new and you just got it; a complete and thourough cleaning. If you use any lube on your molds, wait untill after you try it again. Empty your pot and scrub/wire brush all the junk out of it. Go with virgin alloy. Double check your temps and method. There's a lot of "mebbes" that could apply, but you need to have some "known good" factors (you know you mold is good, you know your alloy is good, etc)

When I run into a wall I use this method and most of the time it works for me...

dragonrider
12-13-2010, 01:12 PM
Check your vent lines, may be blocked.

RobS
12-13-2010, 01:29 PM
I find that people who heat bullet alloys to 800 degrees for any reason just don't get it. Gary

Well I guess Veral at LBT just “doesn't get it” as he tests his molds out at 800 degrees. He does say that it would be better for cooler alloy if you continue to read on though but if not then.......................Post #2 on the page

http://www.go2gbo.com/forums/index.php?topic=197264.0

Now I'm not saying one way or the other and your comments do have good merit, but coming across in the manner that you do really does make a whole lot of good folks look like incompetent fools when they simply are not.

onondaga
12-13-2010, 02:02 PM
I didn't say foolish at all. I hope I got his attention although. He sure is asking for help and I definitely want to learn him away from 800 degrees. I have been called on for telling people that they have ruined their alloy before. I know that is hard to take and accept, but I hope it can be taken as a learning experience and not an insult. I am sure the man wants to make good boolits. He said he got the alloy from Rotometals, they are not cheap. I bet a call to Roto's metallurgist in charge saying something like-- I might have overheated your alloy, at what temperature does the tin separate from this particular alloy? Possibly a more authoritative answer than mine would help.

I have looked at samples of cast over heated alloys in an electron microscope to verify to customers that they have overheated alloys when I was a casting analyst for a precious metal manufacturer in their education department. The structure difference is evident. This is the same with lead alloys and easy to prove--but you need a metallurgy department with an electron microscope as I had, but I am retired now.

Gary

RobS
12-13-2010, 02:23 PM
Gary:
Its the approach in which you deliver that makes people feel foolish or makes them feel offended. Reconstructing the way you write in a more settle means will relay a much better approach to what you hope or want others to understand.

felix
12-13-2010, 02:42 PM
I thought Gary did a very good job, Rob. In my opinion, it is more offensive to quote others in your defense, unless the 'others' are also active participants in the conversation (thread). ... felix

geargnasher
12-13-2010, 02:47 PM
Baahhh. Here we go again.

Gary, your'e spot on with everything I know about boolit casting and non-ferrous metallurgy. I have been beating this same drum for some time now and if people want to get butt-hurt, so be it. Maybe they'll learn something. I found nothing offensive at all in your posts, only your desire to help out and share your valuble knowledge.

Binary lead/tin alloys are most particularly susceptable (sp) to tin "burnout" from alloy overtemp because there is no antimony present to form the tin/antimony intermetallic. That intermetallic somewhat preserves the tin, but anything over 750* still causes it to dross out. 20:1 will dross out most of the tin in a matter of a few minutes at 800*, I know this very well. I was miffed until I read the Metals Handbook and looked at some phase charts for Pb/Sn/Sb alloys, then the old lightbulb came on. My casting temps went way down (75-125* over full liquidus) and I'm much happier, in fact I can drain a 20-lb pot in an hour and barely have any dross form at all on the surface.

Gear

mpmarty
12-13-2010, 02:48 PM
Heck I pour at 800 degrees with my LEE molds all the time and have no problems. Boolits fall free and shine as long as I touch the wet towel with the mold often enough to keep the mold temperature down. I cast 175gr 30 cal and 350 - 450 gr 45/70 stuff as well as 230gr 45acp.

montana_charlie
12-13-2010, 02:50 PM
Gary:
Its the approach in which you deliver that makes people feel foolish or makes them feel offended. Reconstructing the way you write in a more settle means will relay a much better approach to what you hope or want others to understand.
Making a person feel foolish, or slightly offended, will often get his attention when 'false kindness' won't.

If the person admitted to a method, or routine, which is considered to be 'unhelpful', making a point of berating that part of the procedure is sure to get the questioner to thinking about it.
If you are sure you are right (and Gary seems to be sure) then say it straight out...without the kind of 'buttering' this PC society has made people think they deserve.

CM

geargnasher
12-13-2010, 02:57 PM
Felix, you posted while I was typing, my fingers are cold this morning!

Gary, there is a "backyard metallurgy" method for proving how much tin you've lost from overheating a binary alloy, skim off all the dross that formed after the last good flux, then remelt the dross into a solid form with a propane torch and reduce it as much as possible with candle wax (I used a deep spoon for this), then use the water-displacement method to determine specific gravity of the metal, compare to known specific gravities of the two metals in question, and do the math to figure the proportions. I've found as much as 90% tin in dross from binary alloy.

CM, it's never my intent to give information in an insulting manner, but raw facts and data delivered as such are often lacking "touchy-feelie" qualites.

Gear

RobS
12-13-2010, 08:21 PM
Well people, what I am trying to covey here is that by saying a person doesn’t have a clue if they cast at 800 degrees is absurd. I stated that Gary’s post had good merit, never said it didn’t.

Casting at 800 degrees, and many people do, I guess produce boolits which are junk if I understand the logic of this conversation……………This of course is not the case as there are different alloys as well as pure lead which require heat for proper mold fill out...... Anyway, people cast at different temps for different reasons, whatever the case, but to make a statement that if a person doesn't cast at a lower temp that they "just don't get it" is narrow minded and flat out not right. I will not be talked out of the fact that making statements as such isn’t right and that my thought in the matter would place me in the back seat in regards.

Felix, I was referencing Veral’s Post and the thread on the other forum in which it came from as the member there was having a similar experience with mold fill out as it relates to alloy temp/mold temp. I never once quoted anything he wrote. I left the link here on this forum for others here at CB to read for themselves. Referencing Veral is not offensive in the least as it pertains to this thread with similar content. Think of all the research that has been done with reference to other peoples work in the field.

montana charlie, I don't give false kindness nor do I post negative comments either. It should be about providing help to people who are not of teenager mindset (for the most part members here are not like this). The OP is definitely not of such nature, he does not need to feel foolish or be slighly offended in order to learn. Most people here don't require it either and will learn just fine without the negative orientation.

JIMinPHX
12-13-2010, 10:00 PM
I generally don't cast anywhere near 800 unless I am using pure lead. For something like drive key shotgun slugs, I can't seem to get good results much below that temperature & I might go to 825 or even a hair above that if it seems to help. I sometimes cast pure lead round balls around that temperature too. Most of my other casting is done in the 650-720 range, depending on the mold & the alloy. I do notice a goldish skin develop on the surface of the melt if I run the temperature of a rich alloy much more than 50 or 75 degrees above where I need it to be to cast well. I believe that goldish color = lost tin. In general, if your boolits aren't frosty looking yet, you are not even close to being too hot. Even frosty is OK, but then you need to start watching that you don't go much higher.

At least that's my humble opinion in simple terms from what I have seen so far in what casting I have done to date.

onondaga
12-13-2010, 10:33 PM
Looks like mustanggt has nothing to say. I was hoping he would chime in with more specifics. He bought 20:1 alloy and it is reasonable to say that he wanted his boolits to be cast in 20 :1 alloy. It is patently metallurgic science that 20:1 will not remain 20:1 at 800 degrees. The tin will separate, rise up and oxidize very rapidly and constantly lowering the tin content till it is gone at a rapid rate. People that disagree just don't believe in science that disagrees with them. Professionally I had to deal with people doing the same thing with High Noble metals on a daily basis for many years. Many of them cursed me out, threatened legal action, bodily injury and sabotaging my job security because their techniques had been the same for decades and that they never had any problems till the day they called me. They would ultimately complain to the CEO of the corporation after being irate at me telling them they were wrong and the CEO would always tell them, after he looked at the pictures from the electron microscope, You fried the metal, how many people have to tell you we won't give you new gold alloy because you fried it by not following instructions. Then the CEO would apologize to me and thank me for putting up with stubborn people that just don't get metallurgy as well as I do or at least as well as they should know metallurgy when casting gold alloys. Lead is fortunately much less expensive than gold; so tempers don't get to the lethal level, but I am just as sure that mustanggt wants excellent 20:1 cast boolits. I don't think Rob has said much of anything helpful to mustanggt to get better boolits from 20:1 alloy but has passively encouraged him to make worse boolits. I say that Rob should give mustanggt new alloy for free.

kelbro
12-13-2010, 10:46 PM
I found Gary's post educational, not the least bit offensive.

mustanggt
12-13-2010, 10:56 PM
Bullplate. A little dab'l do ya.:)

RobS
12-13-2010, 11:49 PM
I don't think Rob has said much of anything helpful to mustanggt to get better boolits from 20:1 alloy but has passively encouraged him to make worse boolits. I say that Rob should give mustanggt new alloy for free.

Now come on Gary, you don't need to put words in my mouth, you are freakin right with 20:1 lead tin alloy, I never once stated that you were not and even said several times that you had good merit in explaining it. Should I be casting with 20:1 alloy I wouldn't be casting at 800 degrees either.

As to passively encouraging mustanggt to doing so I've not done and apologize if I came off as such. The argument from the beginning was your statement that people just don't know what they are doing if they cast at 800 degrees since every boolit alloy according to you can be cast easily at 675 degrees or less.

Everyone reading the thread, the newbies in particular, need to be aware that not every alloyed boolit metal will be ruined if one cast at hotter temps. I reiterate, you stated that there is no need to cast any boolit alloy at anything but a 675 degree reasonable maximum. BS to that statement as straight WW alloy is PITA to cast in particular with certain molds at 675 degrees and can be impossible under the temperature you consider maximal.


You are going to fight it until the cows come home and I have stated and will again that you are correct with 20:1 alloy, but refuse your comment that all bullet alloy from every mold can be cast at or under your desinated 675 degree maximum alloy temp and that people don't know what they are doing if they do otherwise.

mustanggt
12-14-2010, 12:14 AM
I use bullshop lube. It was in the 50's yesterday and I believe about the same the time before that. My garage is insulated and I have a portable heater that keeps it 60 or so in there so I don't think it is the problem. The only thing I can think of is the rag. I am doing nothing different which is why I am pulling my hair out. I would think that I have cleaned enough already. I can't see any residue and got it as clean as I could. I am buying a new ladle and new pot. They are the ones that are contaminated so I've decided to bite the boolit and do that. If you've got any more advice please give it as I would appreciate it. Thanks alot.

happy7
12-14-2010, 12:18 AM
Well, I don't usually like contentious threads, but I must say this one has been very educational. I sure appreciate all the contributions.

waksupi
12-14-2010, 12:24 AM
I use bullshop lube. It was in the 50's yesterday and I believe about the same the time before that. My garage is insulated and I have a portable heater that keeps it 60 or so in there so I don't think it is the problem. The only thing I can think of is the rag. I am doing nothing different which is why I am pulling my hair out. I would think that I have cleaned enough already. I can't see any residue and got it as clean as I could. I am buying a new ladle and new pot. They are the ones that are contaminated so I've decided to bite the boolit and do that. If you've got any more advice please give it as I would appreciate it. Thanks alot.

If you think you have a contaminated pot and ladle, try sandblasting. Most machine shops have one, and it would be cheap to have done, or they may let you do it yourself.

geargnasher
12-14-2010, 12:54 AM
I generally don't cast anywhere near 800 unless I am using pure lead. For something like drive key shotgun slugs, I can't seem to get good results much below that temperature & I might go to 825 or even a hair above that if it seems to help. I sometimes cast pure lead round balls around that temperature too. Most of my other casting is done in the 650-720 range, depending on the mold & the alloy. I do notice a goldish skin develop on the surface of the melt if I run the temperature of a rich alloy much more than 50 or 75 degrees above where I need it to be to cast well. I believe that goldish color = lost tin. In general, if your boolits aren't frosty looking yet, you are not even close to being too hot. Even frosty is OK, but then you need to start watching that you don't go much higher.

At least that's my humble opinion in simple terms from what I have seen so far in what casting I have done to date.


Jim, gotta correct you on the point I highlighted above in red, as it is another VERY important and often misunderstood by newer casters: POT temperature and MOULD temperature are two completely different things. POT temperature should be maintained at a temperature that is best for the maintenance/casting characteristics of that particular alloy or meta. POT temperature has nothing at all to do with whether or not you get frosty boolits. MOULD temperature is responsible for quality of fillout (assuming good alloy and clean mould), and whether or not the boolits are frosted. As you know, antimony is mostly responsible for the ability of an alloy to "frost" boolits with a very hot mould.

I can cast super-crystallized, unusable boolits from a 650* pot and overheated mould, and shiny, wrinkled, poorly filled out culls with 800* alloy and cool mould. Boolit quality is all about mould temp, pot temp is all about alloy maintenance.

Gear

home in oz
12-14-2010, 01:01 AM
Gary,

I was fine with how and what you said about the melt...

onondaga
12-14-2010, 01:04 AM
mustanggt
The sandblasting will really help if there is contamination. Wire-brushing the pot may also be sufficient. Heat a small amount of alloy, say one pound to about 675 for a good hot pot. Have a wire brush ready that will reach all the surfaces inside the pot. A helper with good heatproof casting mittens and some like mittens for yourself would be helpful and safe to steady the pot for brushing. Unplug the pot and dump the metal to an ingot mold. With help steadying the hot pot upside down and against a safe vertical surface, brush it out firmly and briskly. Table your still hot pot and work the pour mechanism up and down and take the opportunity to use a suitably sized drill held in a pliers to clean the pour spout also by moving the drill up and down. Additional heat applied to the nozzle may be necessary if the drill jams so have a propane torch at the ready. . Be careful not to damage the valve surfaces. This should put your pot in fine shape for a new melt with some alloy from Rob.

When the pot is cool, take the opportunity for some good care of the pot also. Soak it with silicone spray, wipe it out well with a coarse towel and that will remove a surprising amount of remnant oxides and contamination. Spray and rub again if necessary. then a final spray will help keep the pot from additional pot oxidation till the next use. Any remaining volatiles from the silicone will evaporate off with the next run but the silicone remaining will withstand more than even 800 degrees. I generally spray my pot when it cools and this has kept my pot in good serviceable condition for more years than I had expected. I brush and lube the external moving contact areas for the valve actuating parts and the flow adjuster with high heat never seize grease after each use also.

Gary

snuffy
12-14-2010, 01:07 AM
The tin will separate, rise up and oxidize very rapidly and constantly lowering the tin content till it is gone at a rapid rate.

Gary, you've made this statement at least twice in this thread. I believe that to be wrong, or at least worded wrong. I've read here on this forum numerous times, that once lead and tin are alloyed, they can never "separate". That would mean that lead and tin are a suspension, not a true alloy or solution.

To carry your claim to an extreme, if you turned a pot onto it's highest setting, then left a 20-1 lead tin alloy sit for several hours, you'd have tin oxide on the surface and pure lead under it.

Geargnasher convinced me in another thread that tin is oxidized much easier and at a lower temp, which he called there and on this thread as "burning the tin out". I have a PID and have been casting at a much lower temp since then with great results. I seldom go over 725. What helped immensely was getting a hot plate to preheat the molds. This is range lead with about 2% tin and about the same for antimony.

Oh, so why do we flux? Isn't it to return the oxides back into the melt? What you're saying is that casting at 800 degrees, the tin is lost forever. Doesn't fluxing return the tin to the alloy?

I'm not slinging arrows, just want to learn from somebody who should know more than I do. You say you're a metallurgist, so that means you've been to college, something I never had the opportunity to do.

And your post on the top of page 2 is 26 sentences long, without a paragraph break, very hard to read.

geargnasher
12-14-2010, 01:33 AM
Gary, you've made this statement at least twice in this thread. I believe that to be wrong, or at least worded wrong. I've read here on this forum numerous times, that once lead and tin are alloyed, they can never "separate". That would mean that lead and tin are a suspension, not a true alloy or solution. I don't claim to completely understand it, but I can prove that, in effect at least, tin goes away above about 750* because it "hyper-oxidizes on the melt's surface. Tin and lead as a binary form a true solution, but when exposed to oxygen tin will combine with oxygen more readily than the lead will at certain temperatures. Since the alloy in a pot actually circulates even when undisturbed (due to heat loss part of the alloy rises and part falls creating a mixing action that constantly exposes new alloy to the surface) the tin exposed to the surface is constantly oxidizing. If you want to stop it, create a constantly reducing enviroment like charring sawdust or burning wax/oil, you will notice that if you stir through it the melt surface you expose in the wake of your stir stick will be mirror-bright. The thing I can't explain is why the metals continue to oxidize even when a layer of dross has formed which, I would think, should create an oxygen barrier on top of the melt. All I can say is the dross layer will continue to build until all the tin is gone if you leave a lead/tin binary in the pot at 800* . When you get into ternary alloys like Pb/Sb/Sn things get even more complicated due to intermetallic bonds, and add impurities like copper, zink, and bismuth to that you can drive yourself crazy.

To carry your claim to an extreme, if you turned a pot onto it's highest setting, then left a 20-1 lead tin alloy sit for several hours, you'd have tin oxide on the surface and pure lead under it. This will actually happen, and in much less time than you postulated.

Geargnasher convinced me in another thread that tin is oxidized much easier and at a lower temp, which he called there and on this thread as "burning the tin out". I have a PID and have been casting at a much lower temp since then with great results. I seldom go over 725. What helped immensely was getting a hot plate to preheat the molds. This is range lead with about 2% tin and about the same for antimony. The lead oxidizes too, but much more slowly at the temps that tin's oxidation rate is going into hyperspeed. At 1000* pure lead forms dross very quickly, too.

Oh, so why do we flux? Isn't it to return the oxides back into the melt? YES. What you're saying is that casting at 800 degrees, the tin is lost forever. No. Doesn't fluxing return the tin to the alloy? Yes, but the actual composition of the alloy fluctuates between fluxings. Take, for example, a 20LB pot with WW + 2% extra tin. That's somewhere between 2 and 2.5% total tin content, or about half a pound of tin at the very most. Turn it on to 800*, flux it, then leave it alone for half an hour. Skim the dross and weigh it. If you skimmed 4 ounces off, and it will likely be mostly tin, you just went down to just over one percent tin. Drastic change. See how little it takes to change content? Cutting your tin content by 50% will make a noticeable difference in casting qualities. Unless you're stopping to reflux the oxides back in every 5-10 minutes your alloy can change significantly if you're overheating it. The solution is to preheat your moulds, cast fast, and maintain the casting tempo that keeps the mould at the temperature it likes best. Maintain the pot at the right temp for the alloy, and maintain a casting pace that keeps the mould the right temp that IT needs to drop good boolits.

I'm not slinging arrows, just want to learn from somebody who should know more than I do. You say you're a metallurgist, so that means you've been to college, something I never had the opportunity to do. Gary is a metallurgist, I don't claim to be, although I was educated as a mechanical engineer.

And your post on the top of page 2 is 26 sentences long, without a paragraph break, very hard to read.

The bottom line is prove this to yourself. Get a good thermometer for your lead pot, use a known composition alloy, get a temp probe for your mould, and experiment. Observe how long you can keep your alloy's surface shiny in the pot, and how your boolits fill out.


Hope this helps,

Gear

onondaga
12-14-2010, 02:04 AM
Tin oxide can be returned to suspension with agitation but that is by no means permanent in fluid bullet alloy. It floats too because it is lighter than lead and doesn't practically link the same as in a true alloy. Tin oxide is molecular and not elemental like lead and tin so there is a different thing going on there in suspension and it doesn't pattern in chains like lead and tin elements do in alloy. Fluxing does not turn tin oxide back into tin. It helps separate tin oxide and lead oxide from the surface so it is easily skimmed off. My skill in metallurgy is avocational and professional not doctoral. I wouldn't pretend to know it all, but I like this stuff. I am much more familiar with noble alloys used in dentistry but have enjoyed bullet casting since age 7 and noble alloy casting since age 5.

Oh dross-- I don't think it makes a terrific barrier, look how it was described in this thread in proximity with tin oxide as full of pits, it also gets granular and even lumpy or dusty and can be blown off. A good barrier would be like borax melted over gold forming a fluid glass like appearance when it is used as a casting flux for gold alloys. It would be nice if Borax worked at lead alloy melting temperatures. I bet there is something that does( possibly something like the lowest fusing pottery glaze) and would be a good marketable product for bullet casters.. I recently learned the sawdust thing here on this forum and don't understand it. I tried the method with my old standard supply of LEADEX brand bullet casting flux and it has the same effect when used similarly by leaving it on the surface and not skimming it off. It allows me to run a pot down to the last pound without any fuss---I really like that. But I can caution you that tossing sprues in really messes it up and they are better kept till you start a new melt.

onondaga
12-14-2010, 05:03 AM
Burning and oxidizing are synonyms or words that have the same meaning.

Fluxing returns the tin that has floated up to the top from overheating to the alloy and it will stay there pretty well if you lower the heat that caused the problem in the first place. Maintaining the same heat level maintains the repeating of the problem.

Tin oxide and lead oxide are molecular substances bonded at the atomic level and not elemental metals anymore . Fluxing will not turn a molecular substance like tin oxide or lead oxide back into their elements of lead and oxygen or tin and oxygen back into elemental metals and free the remaining oxygen. That would be nice but flux won't do that. Flux mainly changes surface tension while having an effect to briefly retard oxidation. Stirring after fluxing will only temporarily redistribute floated up tin and retard it from burning off (oxidizing) if the temperature is lowered sufficiently to stop the separation of the tin . Those little atoms of lead and tin swim around faster the more you heat them in an alloy. they have a limit to their attraction for each-other in fluid alloy and excess heat disturbs their attraction for each-other. The disturbed tin will float up because it is lighter in specific gravity. Then excess heat will burn (oxidize) it.

Something I do to preserve tin level in my pot is to use a melt that is gentle. I don't turn the dial all the way up to melt a pot of ingots and then turn it down to the number 4 to 5 on the dial that my alloy likes for casting. I melt my ingots at 6 on the dial and patiently wait the extra minutes more than it would take with the dial all the way up. When the ingots are all fluid I turn the dial to 5 , immediately bees wax flux, skim, cover with LEADEX or sawdust. then I wait 15 more minutes for temperature of the pot to stabilize and then finally cast bullets till the pot gets low. None of my alloy ever gets superheated that way and I believe I lose significantly less tin to oxidation than the casters who crank up the dial and fry metal. Between a full pot and a low pot I nudge the dial from 5 to 4 on the way.

I always cast an alloy that is pretty predictable and the process is successfully repeatable. Casting a pot full of bullets at high temperatures results in bullet weight variance as the alloy weight changes due to tin loss. Bullets from the bottom of the pot end up being very measurably heavier than bullets from the beginning of the casting session. The difference definitely is visible in group size that I won't tolerate shooting at the bench or in the field.

Gary

mustanggt
12-14-2010, 10:25 AM
Sorry I haven't posted enough. I am busy and only look at things here and there. I gotta go to work. I will look things over this evening and post more. Thanks.

waksupi
12-14-2010, 12:10 PM
Ya know, putting kitty litter on top of the melt eliminates most of these concerns.

onondaga
12-14-2010, 12:37 PM
I'd like to try Kitty Litter but haven't because I haven't seen reference to a particular type or brand and there is such a variety of Kitty Litters. Can you please share what brand you use and what the composition is?

Gary

snuffy
12-14-2010, 01:27 PM
Well, now I'm really confused. So lead and tin are NOT true alloy? And the old myth that tin "floats" out of the melt is actually true? Yes, I understand that tin is lighter than lead, but that lead/tin AND antimony alloys are just that true alloys, they can't/won't layer out or separate due to differences in density.


Tin oxide and lead oxide are molecular substances bonded at the atomic level and not elemental metals anymore . Fluxing will not turn a molecular substance like tin oxide or lead oxide back into their elements of lead and oxygen or tin and oxygen back into elemental metals and free the remaining oxygen.

So how is lead ore smelted? Don't they add carbon to it to get the lead oxides into the metallic state? Since most of our fluxing agents are carbon based, aren't we smelting on a small scale?

Whenever I flux, the scum disappears leaving only some dirt and shiny metal. The scum is lead and tin oxide, where did it go?

pearson1662
12-14-2010, 01:30 PM
Well, I don't usually like contentious threads, but I must say this one has been very educational. I sure appreciate all the contributions.

+1 from this relative casting neophyte

felix
12-14-2010, 01:30 PM
Gary, look for a kitty litter that might say composed of drilling mud, bentonite clay, Montmorillonite clay. Those things contain aluminum compounds and for some reason (as they are anti-flux agents in lead alloys) work well for us. ... felix

snuffy
12-14-2010, 01:57 PM
The bottom line is prove this to yourself. Get a good thermometer for your lead pot, use a known composition alloy, get a temp probe for your mould, and experiment. Observe how long you can keep your alloy's surface shiny in the pot, and how your boolits fill out.


Gear, notice I said I have a PID temp control on my pots. I also have a RCBS thermometer, but I borrowed it to a buddy that I got started casting, I doubt I will see it back. So I know the temp I'm casting at. As for the mold, I have an infrared thermometer that I can shoot at the sprue plate to judge the temp of the mold. It don't read well off the shiny aluminum, so it's ether the dark sprue plate or the handles. My guess is it's all relative, when I find what temp that mold works at, I should record it and the melt temp. when I'm getting good looking boolits.

Gary, my PID starts out at full powder until the lead reaches about 75 degrees shy of the set temp. That means it has the element on constantly until around 625-50 if the temp is set @ 700. This is on a pro 20 lee. The stock thermostat would be cycling on-off way before it got to set temp, resulting in a longer wait before casting can begin. I thought this to be one of the benefits of the PID. The other is the ability to control within +-2 degrees if the melt is left undisturbed.

You're saying that would burn the tin that's in contact with the sides of the pot that's in contact with the heater element? There's always a thick layer of scum after the melt comes to temp but it always re-combines when I flux.

montana_charlie
12-14-2010, 02:11 PM
Tin oxide and lead oxide are molecular substances bonded at the atomic level and not elemental metals anymore . Fluxing will not turn a molecular substance like tin oxide or lead oxide back into their elements of lead and oxygen or tin and oxygen back into elemental metals and free the remaining oxygen. That would be nice but flux won't do that.
Explain reduction...

CM

geargnasher
12-14-2010, 03:25 PM
I was thinking the exact same thing, CM.

Gary, I think one of us lacks a little understanding of what takes place in a reduction reaction, and I'm curious who, because you may know something I don't. My observations of reducing oxides in the melt back up what I know chemically. Just about any organic substance containing carbon (by definition all organic substances do), particularly hydrocarbons, certainly seems to turn oxidized lead, tin, and to a certain extent antimony back into elements and free them of the oxygen. This apparent reaction of, for example charring sawdust, "reduces" the dross and oxides drastically and only leaves a tiny bit of grey ash behind. The melt will be mirror-bright, homogenous, and will cast well. Stirring with a clean, dry stick until it begins to char has this effect, as does smoldering sawdust, boolit lube, beeswax, petroleum oil, you name it. Kitty litter serves to insulate the melt both from heat and oxygen, but does not induce a recuction reaction because it lacks free hydrocarbons.

If the reduction of oxides back into their elemental form is not what's taking place when using a hyrocarbon reducant, then what IS happening? Please understand that I'm not confusing "fluxing" with "reducing".

Gear

geargnasher
12-14-2010, 03:40 PM
Snuffy, sorry I missed those facts in your case, but I was making a kind of general statement directed at the OP anyway, you aren't the only one reading this.

I take it you wired around (bypass) the pot's thermostatic switch? That's the way I did mine, and it works great. Just let the SSR do the work. As for the mould, you can drill into it and insert a temp probe into the blocks if you really want to know. You can also wire a PID temp control to a hot plate, put a steel electrical work box over the burner to create an "oven", and preheat your mould to an exact temperature.

Gear

onondaga
12-14-2010, 03:40 PM
Tin and lead make a true alloy with some limitations. You can over heat the alloy and disturb it causing the float up and oxidation of tin and you can easily burn all the tin off at 800 degrees in a hurry. The link between the elemental chains of lead and tin in alloy is not indestructible and excess heat will disturb the link. Adding Antimony will strengthen the linking chain of the three elements to a greater degree than the chain linking of only tin and lead. The stronger linking with antimony added to the alloy is the principal reason why only small percentages of Antimony bring BHN numbers up so much faster than only bringing up tin levels in the alloy accomplishes.

Fluxing of scum doesn't make it disappear. The tin that wasn't fried can be mixed back into alloy if temperatures aren't too high. The centripetal and centrifugal forces of rapid stirring sends some of the fried metal oxides and flux ash to the middle and perimeter of the top of the melt where they can be skimmed. Nothing is disappearing here. Changing and relocating would be a better name for it.

Ouch, I am finally getting a headache. I think somebody wanted that.

Gary

geargnasher
12-14-2010, 03:51 PM
Gary, I don't buy it. "Fluxing", whatever that is, may or may not reduce oxides (reduction reactions are the reverse of oxidizing reactions, it's what makes rechargable batteries work), but what I call "reducing" the melt by introducing the right stuff to the dross sure does make the scum, dross, and oxides disappear from my melt.

I used to "smelt" small batches of specialized boolit alloy in my casting pot and reducing the oxide scum was a priority. I then would empty the pot quickly into ingot moulds, and there was almost zero ash or dross remaining when I was done, although I had "reduced" a couple of tablespoons full of dross from the surface and skimmed the pinch or so of ash left. It went somewhere, and it wasn't in suspension in the pot. It didn't go out the spout into the ingots, either.

Gear

geargnasher
12-14-2010, 03:53 PM
[snip] ...You're saying that would burn the tin that's in contact with the sides of the pot that's in contact with the heater element? There's always a thick layer of scum after the melt comes to temp but it always re-combines when I flux.


Oxidation reactions can't take place without oxygen. How much oxygen is between the metal and the sides of the pot? I figure most of the oxidation takes place at the surface.

Gear

onondaga
12-14-2010, 04:15 PM
I believe the amount we disagree about the differences between fluxing and reduction is due to the circumstance of the of the pot itself and percentage of each that go on in a pot independently or cumulatively with a variety of both. There is merit to both . I believe there is a lot less reduction going on there than you do. It is a matter of degree with each and either would be difficult to absolutely prove. I can agree to disagree with you. Pot conditions and exact fluxes limit and promote either or both. A 50:50 alloy will react much more closely as you predict, granted, I think a 20:1 will react more closely to what I suggest. Antimony would close the gap quite a bit!

The 20:1 starting the thread is what I have been concentrating on.

Also, I sincerely suspect that you don't fry your alloy at all, so you don't need to worry about tin very much.

Gary

felix
12-14-2010, 04:28 PM
Gear is correct, Gary, in most situations we have at home in the pots. You both know that there are certain percentages of elements that make up a saturated solution at a certain temperature, pressure, and volume of each constituent independently. The problem is that that solution will break up when any outside condition changes, like temp and/or pressure. So, what is in the pot at any certain instance, might not be in the poured boolit in the same ratios. That is why mold, pot, boolit are together big time in making very consistent solid boolits. Air bubbles are the biggest concern in finished boolits in making BR quality boolits, such as those that will shoot half inch at a hunnert. However, when the solution is truly a solution at boolit time, you both know that the boolit freezes all at once; also, the freeze time is sporadic whenever the solution is not a solution. You can tell the difference by boolit hardness a month later (for sure). A perfect solution boolit will be just as hard as when dropped as a month later. The odd ball boolit will be harder, and much harder when cooled very rapidly as by water dropping. ... felix

Gary, well, you said so in your last post above.... felix

onondaga
12-14-2010, 04:48 PM
Thanks Felix, I am gettin killed here! I worked for a gold refinery, not in a lead refinery. This has been fun.

Gary

swheeler
12-14-2010, 04:56 PM
Gary, I don't buy it. "Fluxing", whatever that is, may or may not reduce oxides (reduction reactions are the reverse of oxidizing reactions, it's what makes rechargable batteries work), but what I call "reducing" the melt by introducing the right stuff to the dross sure does make the scum, dross, and oxides disappear from my melt.

I used to "smelt" small batches of specialized boolit alloy in my casting pot and reducing the oxide scum was a priority. I then would empty the pot quickly into ingot moulds, and there was almost zero ash or dross remaining when I was done, although I had "reduced" a couple of tablespoons full of dross from the surface and skimmed the pinch or so of ash left. It went somewhere, and it wasn't in suspension in the pot. It didn't go out the spout into the ingots, either.

Gear

I believe that scum on top of your pot before fluxing is a mechanical mixture of metal and metal oxides. The fluxing/introduction of hydrocarbons/ allows the metal to return to the melt, leaving the metal oxides as dross to be skimmed off. You might call this process reduction but it is not changing metal oxide back to elemental metal.

felix
12-14-2010, 04:57 PM
Nah! Getting killed, no way! I will trade you boolits for gold ANYTIME!!!! And, I bet Gear would do the same, and, in fact, he will deliver in a truck he built just for the purpose. ... felix

Suo Gan
12-14-2010, 05:03 PM
I have NOT read what the others have said. My first question is what are you using to flux with? Use bullet lube, candle wax, sawdust, etc. and stir and scrape the sides with a wood stick or piece of kindling. Touching your ladle to something carbon based will only flux your pot when it melts. You say you are running it hot. Perhaps you cooked off some tin in the process of all your trials and tribulations. I would add some tin to your alloy. Also as you know, any spot of oil or grease that might be in your cavities WILL screw you up. If you perhaps added a little too much lube to your sprue plate pivot, perhaps it migrated to the cavity? Check you mold venting to. I use a sharp carbide pen to clean or touch the vent lines up...BE CAREFULL and don't overdo it! Try dipping your mold corner in the alloy until alloy does not stick to it. I keep my molds hot by using a hot plate. I am willing to bet this is a vent issue. Perhaps champhering the corner of one half of the mold block would be a last resort.

You can bet that every time a question of this nature is brought up some of the guys get into some very COMPLEX science behind alloying and it just complicates things much more than need be IMHO. Keep it simple. Take the advice given you with a grain of salt. View it as a learning experience, and when they start talking over your head remember they were pouring good boolits a long time before modern chemistry and Redox reactions were understood. I am sorry that you are frustrated, I have been there myself so I can sympathize. Just take breaks and don't get burned out. Good luck to you!

felix
12-14-2010, 05:06 PM
Swheeler, that all depends on the mix and ambient. Sometimes a different flux works mo'betta' under one set of conditions, and that would be unknown by me why, when, and where. I just know that dross looses weight when things change, and other times, the dross gets even heavier. Therefore, what you and Gary are saying is the truth under many conditions. ... felix

montana_charlie
12-14-2010, 05:29 PM
I use 20-1 alloy almost exclusively.

When I 'smelt' collected metals to produce clean ingots, I 'flux'...usually with wax.
When I use clean ingots to cast bullets, I 'reduce'...with wood.

I allow a layer of scum to build up on my alloy while I cast a certain number of bullets...then I 'reduce'.
After thoroughly stirring and scraping with the stick, I gather all of the scum to the side of the pot. There is probably the equivalent of a heaping teaspoon of metal oxides in that pile.
If this scum was skimmed out, it would weigh almost as much as lead does.

With the stick, I will press part of the pile of scum against the side of the pot and force it down out of sight...then scrub it up and down for several strokes.
During this time, dark ash will bob to the surface, but no metallic scum.

I will work over all of the pile of oxides that I collected...and gather up any more that forms while I am working.

When finished, there will be (maybe) a quarter teaspoon of dark ash remaining...and no silver or grey colored 'scum'.
I dip the ash out, and dump it in a waste can...noting that it has no detectable weight.

If onondaga doesn't think that reduction can occur, maybe it's because he doesn't know how to do it.

If what I am doing is not reduction, perhaps onondaga can try it himself...then tell me what is actually happening.

If onondaga doesn't care to try, perhaps swheeler (the other naysayer) will...

CM

Suo Gan
12-14-2010, 05:49 PM
Needing to know the difference between substitutional and interstitial alloys is questionable for the pouring of good boolits. Understanding that tin oxidizes internally and causes boolits to become harder over time is somewhat Cliff Clavenesk considering the task at hand...but nonetheless interesting, at least to those with lead running through our veins.http://webcache.googleusercontent.com/search?q=cache:3CxFvbQQe4IJ:www.spaceflight.esa.in t/impress/text/education/Solidification/Phase_Diagrams.html+interstitial+lead+tin+alloy&cd=2&hl=en&ct=clnk&gl=us&client=firefox-a
Scroll Half way down and I cached it for ya

PS You CAN cast good boolits without knowing any of this stuff...

felix
12-14-2010, 06:12 PM
Very good! Thanks, SG. ... felix

Bass Ackward
12-14-2010, 06:16 PM
I read and have read a lot about metallurgy over the years. And I am here to say, I appreciate the education.

But ...................... quite often I see things with different mixes, at different temps, at different humidity levels that don't seem to follow "the rules" and I do use a thermometer.

For me, the secret is being flexible to flux with this or that until it cleans up and I get the job done.

People fail to understand that sometimes, you have to turn up the heat to find out what really is on a man's mind. What seems contentious because of the diction, I see as someone having my best interests at heart. Get him emotional and he will write more than one line.

By the way, for those of you in need, I do offer classes in tact. They ain't worth too much so I throw in some political correctness to make sure you get your money's worth.

PM BA Bore if you want to register and sign up. Please don't hesitate to tell him I sent ya. :grin:

felix
12-14-2010, 06:38 PM
The phase diagrams get really interesting when a multitude of stuff is added to our pot. Copper, nickel, arsenic are typical impurities used to play games, like making low speed bearings last a lifetime. The pressure carrying capability of these type of bearings is worth fighting for. Making boolits from the addition of this kind of babbit material is a never ending process because you never know "who done what, when, and how" so as to make batches consistent one day to the next. Impossible using home equipment without looking at grain structures and knowing what caused what. Sooner or later the lack of interest sets in and we just feel lucky we got at least one batch of "perfect" boolits for shooting flies at a hunnert. ... felix

mustanggt
12-14-2010, 09:32 PM
Sorry for the disjointed replies. I'ts because of my getting email notifications that occured hours before so if my replies look inane it's because I answered them from my email alert. I'm still trying to catch up with all of the replies so I'll do it piecemeal. To provide further info: I was using a Lee 20# magnum melter not a bottom pour for the 20-1 alloy. My normal procedure is to flux 3-4 times before I add any alloy back into the pot. After I gave up in frustration with that I went to another Lee 20# bottom pour I have for hardball alloy. Some of what I am hearing I can see using on a bottom pour such as "sealing" the surface of the melt with sawdust etc. to stop the tin from oxidizing. However since I pressure cast those big boolits with a ladle how would that apply to dipping. I try to keep my alloy at 700-725. However, as things weren't going as I expected or hoped I started to try to up the temp a bit to see if that might help with fill out. I tried fluxing more and so on till I couldn't make a difference. That's when I figured it had to be the rag that melted which contaminated the ladle and pot. So I poured the lead out and wire brushed it till it appeared everything I could see was out, then I sprayed liberally with CRC break cleaner and let it sit overnight as well as the ladle. The Lyman ladle is difficult to clean the inside so I don't think I got it clean enough. The pot looked almost clean as new. It seemed all was well as started over with new alloy and went through the process of melting the alloy and heating the moulds on a hot plate. I poured for an hour and saw a steady heat up of the moulds as the boolits started to show some improvement. Then the improvement stopped and I couldn't get the bases to fill out at all. I would think that casting for an hour after the melt is up to temp and the moulds have been heating for half an hour. So I'll read more and post a little later. Thank you

HangFireW8
12-14-2010, 10:38 PM
mustanggt,

You mentioned Bullshop lube earlier on, and not being able to get good base fillout. Assuming you are not using a nose pour bullet, I wonder if you have a sprue plate venting problem, which can be made worse by introducing a lube on the sprue plate. This seals it off and prevents air escaping.

Whenever I apply Bullshop Lube, I try to keep it to a minimum, but on some molds with tight sprue plates I usually get a few rounded bases, then a few with little half bubbles on the base, then things usually settle down to good casting. If it doesn't I have to adjust the sprue plate tension or maybe even file some new vent lines.

-HF

Suo Gan
12-14-2010, 11:32 PM
Sorry for the disjointed replies. I'ts because of my getting email notifications that occured hours before so if my replies look inane it's because I answered them from my email alert. I'm still trying to catch up with all of the replies so I'll do it piecemeal. To provide further info: I was using a Lee 20# magnum melter not a bottom pour for the 20-1 alloy. My normal procedure is to flux 3-4 times before I add any alloy back into the pot. After I gave up in frustration with that I went to another Lee 20# bottom pour I have for hardball alloy. Some of what I am hearing I can see using on a bottom pour such as "sealing" the surface of the melt with sawdust etc. to stop the tin from oxidizing. However since I pressure cast those big boolits with a ladle how would that apply to dipping. I try to keep my alloy at 700-725. However, as things weren't going as I expected or hoped I started to try to up the temp a bit to see if that might help with fill out. I tried fluxing more and so on till I couldn't make a difference. That's when I figured it had to be the rag that melted which contaminated the ladle and pot. So I poured the lead out and wire brushed it till it appeared everything I could see was out, then I sprayed liberally with CRC break cleaner and let it sit overnight as well as the ladle. The Lyman ladle is difficult to clean the inside so I don't think I got it clean enough. The pot looked almost clean as new. It seemed all was well as started over with new alloy and went through the process of melting the alloy and heating the moulds on a hot plate. I poured for an hour and saw a steady heat up of the moulds as the boolits started to show some improvement. Then the improvement stopped and I couldn't get the bases to fill out at all. I would think that casting for an hour after the melt is up to temp and the moulds have been heating for half an hour. So I'll read more and post a little later. Thank you

I don't think that your ladle was contaminated. I think that you are getting poor base fillout because there is grease or oil that got into the cavity from via the oil from the SP pivot migrating there. I would clean the mold real good with soap and water and start fresh. I have had very little success using break cleaner, carberator cleaner is better. But it is cheaper and more effective to just use dish soap. Also you only need your SP to be tight enough to form a square boolit base. This could be a vent line issue, check your vent lines and loosen your SP. It should swing freely with very little help from you. After rereading your issue I do not think that your problem was caused by lack of tin in your alloy.

Here is a fantastic article (Since we were on the subject). He also sums up what I was trying to say earlier: "A novice bullet caster can have much of his or her new-found enthusiasm quenched by the clamor, confusion and paranoia surrounding bullet hardness. This is a shame because understanding alloy suitability is not that complicated and bullet casting really is a lot of fun and allows a shooter (novice and master alike) to get so much more out of their hobby."

Read more here: http://webcache.googleusercontent.com/search?q=cache:3CxFvbQQe4IJ:www.spaceflight.esa.in t/impress/text/education/Solidification/Phase_Diagrams.html+interstitial+lead+tin+alloy&cd=2&hl=en&ct=clnk&gl=us&client=firefox-a

runfiverun
12-14-2010, 11:59 PM
this is a great thread...... i actually read it all.
i'm gonna take a stab at the pouring issue.
your pot may simply be wearing out, my lee would never ever get over 625 since it was brand new.
i finally adjusted the points to get the temp higher.
and could get the alloy temp up to 800 i then backed the adjustment down so it wouldn't go over 725.
if it is only the one mold giving you problems i'd look at the mold- venting,or sprue plate tightness.
if another mold or two does the same thing look at your alloy temp.
as far as fluxing goes i keep different fluxes on hand as i too have found that occasionally the pot doesn't respond to what i am using.
one time the sawdust works perfectly the fourth time later i gotta burn some parrafin [or lube FAIL] to clean up the alloy and reduce the metal back.
heck even marvelux has done fine and i just get a light grey dust.
i also like to crush kitty litter if i am going to use it as a barrier and i still sprinkle saw dust in with it.
maybe the carbon chain gets too long, err short, like it does finally in oil refining, and no more product is refinable [breakable chain] untill another process is introduced to make lighter and lighter grades of petroleum.?

mustanggt
12-15-2010, 12:12 AM
I clean anything touching the lead with break cleaner. I douche the **** out of it several times. I flux with parrafin wax. I use bullshop sprue lube. I have learned not to use very much of that stuff. What I thought was just a little was way too much so I have just used very little. Thank you for the education I can't say I understand some of it but I learned alot none the less. Everything I've done up until just recently has been very sucessful and I have been pleased with my efforts. The non-cotton rag I believe was where I went wrong. I was just so frustrated with trying to recover from my mistake that nothing I did improved the situation. I will double check the sprue plate for free play and try again as well as the vent lines.

geargnasher
12-15-2010, 12:58 AM
I use 20-1 alloy almost exclusively.

When I 'smelt' collected metals to produce clean ingots, I 'flux'...usually with wax.
When I use clean ingots to cast bullets, I 'reduce'...with wood.

I allow a layer of scum to build up on my alloy while I cast a certain number of bullets...then I 'reduce'.
After thoroughly stirring and scraping with the stick, I gather all of the scum to the side of the pot. There is probably the equivalent of a heaping teaspoon of metal oxides in that pile.
If this scum was skimmed out, it would weigh almost as much as lead does.

With the stick, I will press part of the pile of scum against the side of the pot and force it down out of sight...then scrub it up and down for several strokes.
During this time, dark ash will bob to the surface, but no metallic scum.

I will work over all of the pile of oxides that I collected...and gather up any more that forms while I am working.

When finished, there will be (maybe) a quarter teaspoon of dark ash remaining...and no silver or grey colored 'scum'.
I dip the ash out, and dump it in a waste can...noting that it has no detectable weight.

If onondaga doesn't think that reduction can occur, maybe it's because he doesn't know how to do it.

If what I am doing is not reduction, perhaps onondaga can try it himself...then tell me what is actually happening.

If onondaga doesn't care to try, perhaps swheeler (the other naysayer) will...

CM

CM, my results as well, but with WW or other alloys that contain antimony/"other stuff" the pinch of fine ash that is the sole byproduct of several strirrings/scrapings/mashings/skimmings is just like powdered ash from a cigarette. I even mixed some with water once and it dissolved completely. I tested the pH, and, guess what, the solution was a mild base! No appreciable amount of metal in there that I know of.

My usuall alloy is something similar to clip-on WW alloy, or a concoction of scrap that is about as close as I can come to it, usually 3-4% Sb and at least 2% total Sn. I almost always flux/reduce with hardwood sawdust and stir with a maple rick ripped from 3/4" cabinet lumber. The results are always the same, I can take one or two tablespoons of stuff that looks like aluminum slag and make boolit metal out of it again. I can also skim all that stuff off and reduce it OUTSIDE the pot, with no other metal present, just by adding a blob of boolit lube and melting it with a torch and mashing it around with a stick. This usually reconstitutes a high-tin nugget that can be thrown back in the pot.

Gear

blackthorn
12-15-2010, 11:24 AM
I have been following this thread with a great deal of interest and I have to say I seem to be getting more confused as it unfurls. I am not particularly formally well educated, having left school with a partial grade 11 only, so please bear with me if I am way off course. My confusion seems to stem primarily from the opinions expressed as to the ability of “flux” to change oxides back into their original metal form, allowing them to return to the alloy as a useful constituent. As I read over some of the posts, a light (very dim) flashed into what little brain I have, and that idea is that, at least in some respect, we are talking about two different things. This epiphany, if you will, occurred when a previous poster commented that flux “does not turn tin oxide back into tin. It helps separate tin oxide and lead oxide from the surface so it is easily skimmed off”, and then referred to the performance of Borax as a “flux”. I was suddenly reminded of my (very short) association with Marvelux which as I recall formed a semi-hard, somewhat gooey, cover on my alloy significantly enriched by all the dross (including my precious oxides), which then had to be skimmed and relegated to the garbage can, (not to mention the stuff was hydroscopic and the problems that caused me). In previous thread(s), I have seen what we often generically refer to as “flux” called a “reductant” so can someone please enlighten me? Is material that burns and produces carbon a “flux” or a “reductant”? Does it “de-oxidize” oxidized metal? Can we indeed return the oxidized tin/lead to the alloy, or is it rendered useless once it has oxidized? Inquiring minds want to know! Have a great day!
I realize some of my confusion has been addressed while I was struggling to produce this but---nevertheless---

acl864
12-15-2010, 11:38 AM
There has been some great discussion in this thread. Thanks to everyone for sharing what they know.

To the man that's been casting since he was 5... you are one hard core dude.

mdi
12-15-2010, 12:03 PM
Wow! See how much trouble a thermometer can cause? I don't use one so I'm safe here (If I cast at over 800 degrees I don't know it![smilie=l:)

lwknight
12-15-2010, 02:35 PM
Typically , what we use for " flux " is only a reductant. Wood , wax , tar or whatever are not truly fluxes. A true flux like borax is a catalyst that helps pre clean and create the inter metallic bond between different metals.

An example of a strong flux is zinc chloride. It is hygroscopic and is a thick paste. This will cause tin and lead to bond to just about anything that it can like copper , brass and even steel. Zinc chloride will also reduce the oxides back into solution.

I would not use zinc chloride because its nasty. Some fluxes are reductants and catalists both .

Whoever says that you can fry your alloy to an irreversible state with a little homemade smelter has been breathing too much fumes over the years. I have had gobs of dross from linotype and other stuff like bullets and wheel weights that will reduce 99 percent.

I can and do spend a whole casting session without " fluxing " anything and yea there is some dross build up and I just leave it alone. It only gets so thick and stops building. Then at the end of the session I will turn off the heater and toss in a half pecan sized piece of wax and stir and smash the dross back into solution while the wax is yet burning. The temperature starts declining quickly so very little dross comes back before it cools.

Walter Laich
12-15-2010, 03:03 PM
Not to hijack the thread but in one of your posts you wrote:
noble alloy casting since age 5

I know noble gases are over on the right side of the periodic table--just wondering what noble alloy is

thanks
walt

Harter66
12-15-2010, 03:33 PM
Maybe its 1 of those high rent things

geargnasher
12-15-2010, 03:38 PM
From Medilexicon.com: noble metal
Type: Term

Definitions:
1. a metal that cannot be oxidized by heat alone, nor readily dissolved by acid, gold, platinum.

Synonyms: noble elemen.

noble alloy
Type: Term

Definitions:
1. an alloy that has a noble metal content equal to or greater than 25% by weight.



I don't think it's a particular catagory of the periodic table, but more of an industry term for properties of certain materials. Like the term "robust" used by programmers.

Gear

onondaga
12-15-2010, 03:41 PM
A Noble alloy in dentistry standards is one that contains 51% or more gold or combination of other noble metals such as Platinum, Silver, Palladium etc. In other applications the term Noble is more broad. I learned centrifugal casting and potato casting with gold alloys as a small boy helping my grandfather in his dental practice in the 1950s. I cast small inlays, onlays, full gold crowns and gold bridgework. He was instrumental in financially rehabilitating the gold refinery I worked in when an adult. The refinery produced dental casting alloys. I still have several 2 ounce 24K casting gold ingots in a safety deposit box that my Grandfather willed me as my last resort nest egg. In the 50s gold was only $30 per ounce! They have a few of my teeth marks on them from when I was a boy. I just had to bite them.

Gary

runfiverun
12-15-2010, 03:50 PM
he's talking gold, platinum. that kinda stuff.

if i were to look for further education i could read at my own pace.
I'd read up on carborization. [sp?] carbeurization. [been going without sleep too long]
anyways it's the way carbon affects mixing of elemental alloys.
or just try some pine tree sap.

save what does come from the pot and rework it when smelting or in a separate pot.
i use a 10 lb lyman ladle pot to reduce skimmings down as much as possible.
on dross i see beads of alloy in but i can't get to fall through. i'll take some lead and melt through the dross.

geargnasher
12-15-2010, 03:59 PM
Gary, I want you to know none of us are trying to discredit you or "beat up' on you, it's just that you have said some things about lead alloys that oppose the common understandings some of us have about them, and I for one certainly want the better knowledge. If you know something I don't about the oxidation/reduction of boolit metal that could better my casting experience and that of others, I'd sure like to hear about it. If I'm wrong about preaching "reduction" to newer casters, I'd like to know that, too. Remember, boolit metals are different from "noble metals" because boolit alloys certainly DO oxidize with only heat as a catalyst. My understanding is that reduction of these oxides is achieved with the introduction of heat and carbon, but it has also been my observation that pure carbon alone does absolutely nothing to reduce oxides, there has to be an oxidation reaction (combustion) going on on to actually reduce the dross (that means smoldering sawdust, lube, or burning lube/oils.

As an aside, a trick that helps greatly when "smelting" heavily oxidized scrap like sewer pipe joints and roof flashing is to pour a cup of old diesel fuel into the smelting pot and light it when you light the burner. This creates an oxygen-starved, reducing enviroment in the pot with lots of sooty carbon beign created from the poor supply of air to the inside of the pot. Not only does this add lots of cheap BTUs, but it creates the active reduction reaction that seems to reduce the oxides as the metals melt, leaving only non-metal debris floating on top to be skimmed when everything is melted and stirred up well.

Gear

onondaga
12-15-2010, 04:30 PM
An old friend, just days ago gave me 50 lbs of heavily oxidized 1 lb mystery lead alloy ingots. I may try your diesel trick on that. They are nasty. Thanks.

Gary

JIMinPHX
12-15-2010, 08:32 PM
Jim, gotta correct you on the point I highlighted above in red, as it is another VERY important and often misunderstood by newer casters: POT temperature and MOULD temperature are two completely different things. POT temperature should be maintained at a temperature that is best for the maintenance/casting characteristics of that particular alloy or meta. POT temperature has nothing at all to do with whether or not you get frosty boolits. MOULD temperature is responsible for quality of fillout (assuming good alloy and clean mould), and whether or not the boolits are frosted. As you know, antimony is mostly responsible for the ability of an alloy to "frost" boolits with a very hot mould.

I can cast super-crystallized, unusable boolits from a 650* pot and overheated mould, and shiny, wrinkled, poorly filled out culls with 800* alloy and cool mould. Boolit quality is all about mould temp, pot temp is all about alloy maintenance.

Gear


I usually change my mold temperature by changing my pot temperature. Perhaps I oversimplified things a bit too much. Perhaps I get away with this because I cast with a forging alloy. Perhaps I don't understand the details of this as well as I should.

JIMinPHX
12-15-2010, 08:40 PM
The centripetal and centrifugal forces of rapid stirring sends some of the fried metal oxides and flux ash to the middle

Gary,
Can you explain the difference between centripetal and centrifugal forces? I always thought that they were the same thing.

That's an honest question. I'm not trying to break your chops.

mustanggt
12-15-2010, 08:46 PM
I never believed I could've gotten this many posts on this thread. It's very informative when the conventional norms are scrutinized and debunked or a better understanding is gained. I have gained much knowledge in which to try for myself and hopefully improve my casting ability. Thanks again for all the help, but don't stop, keep the discussion going so we may learn more.

JIMinPHX
12-15-2010, 08:46 PM
Kitty litter serves to insulate the melt both from heat and oxygen, but does not induce a recuction reaction because it lacks free hydrocarbons.


No free hydrocarbons? Maybe you need to get some used kitty litter. :kidding:

geargnasher
12-15-2010, 11:36 PM
No free hydrocarbons? Maybe you need to get some used kitty litter. :kidding:

HEEEEEE! I have three cats, only one full-time indoor, but that would be a trip. I wonder what cat pee does to lead? :kidding:

Try adjusting your casting pace up or down to keep the mould at the temperature it likes for casting, and try keeping the pot at a constant temperature in the range best for the alloy (try 675* for WW alloy, 850+ for pure lead, and 725 for any lead/tin binary, 600 for straight lino). I've found that without a PID controller it's pretty hard to keep a pot consistent, especially the bimetal "thermostat" control of Lee pots. One more thing, I finally licked the Cruise Missile! Use a rowel ladle and straight wheel weights without any additional tin. Pressure cast with the ladle.

Gear

onondaga
12-16-2010, 12:11 AM
Robert,
Stir your alloy so fast in the pot that the middle funnels down like a whirlpool and then pull the stirring stick out and watch the swirl. It is centripetal force that draws crud to the center funnel and it is centrifugal force that draws crud to the outer circumference.

I thought I was going to get asked what potato casting is! Potato casting is an ancient art and very scary to do. It is the original method for high pressure casting and beside dentistry, potato casting was also used to cast silver bullets by early Americans. I might be the only person left on the planet that has done it.. I gotta see if there is a Youtube video on potato casting....Nope, nothing there.

Gary

lwknight
12-16-2010, 12:32 AM
potato casting was also used to cast silver bullets by early Americans. I might be the only person left on the planet that has done it..
OK now you dunnit!! We have had several discussions about how impractical it is to make silver bullets. So now your saying that we might have the technology growing in the south 40?

onondaga
12-16-2010, 03:42 AM
It isn't impractical to make silver bullets, just slow. You would need:

1. Low temp Gold casting investment material, water mix type from a dental lab supplier.
2. Steel investment rings and bases and tongs to hold a hot ring. same supplier
3. Silver
4. Potato, big, cut in half.
5. wax bullet patterns and 8 gauge wire wax. You have to make wax bullets to size.Your bullet mold will do with mineral oil separator painted in it. Pour wax or squirt glue gun into mold.
6. Burnout furnace that will hold a temp 100deg. less than silver fluid temp.
7. A torch that will melt silver.
8. Safety casting or welders mittens, thick cotton work glove, clear face shield.
9. A granite floor tile on your bench top.

Method:
1. make wax bullets
2. Attach wax bullet nose to ring base sprue area with 1/8 inch of wire wax.
3. place ring on base, mix investment and brush bullet with investment,then pour investment to fill ring. allow to set up.
4. Remove base only from ring.
5. Carve a second dimple next to the sprue big enough to hold the silver needed to fill a bullet and 1/2 the sprue. This is a careful measurement for the amount of silver you will be using and the size of the dimple or you can really get hurt or killed.
6. Cut a trough between sprue and dimple 1/4 inch wide.
7. Place ringed investment in cold furnace sprue down, bring up to silver fluid temp.
8. Remove hot ring (Wax will be gone) with tongs and hold ring against granite tile on an angle so you can place silver in the dimple and it wont pour into the sprue. Work on a stone slab about 1 square foot, A granite floor tile is nice.
9. Torch the silver till it slumps, sprinkle borax on it. A helper is best to sprinkle at your word so you don't lose heat.
10. Torch silver till it pools and oxides begin to clear to edges of pool, silver won't completely clear like gold will. Put torch aside very quickly. A second person to grab it is best. This must be very quick. I never did it alone.
11. Immediately tip ring flat on the granite, hold tongs firmly and as the silver runs in the sprue. Firmly grip potato round side and slap the flat cut side of the wet raw potato over the whole ring top sprue and all. Hold very very firmly 30 seconds. Steam will be gushing hard and loud. A good casting mitten over a glove is needed for this.
12. The violent and scary steam pressure will force the silver to completely fill the mold. If you used too much silver it is going to squirt out and get you bad.
13 allow to cool then de-vest your single bullet. Cut the sprue from the bullet tip.
14. You are done with one bullet.

If you have a number of ring and base sets to fill your furnace you could make that amount of bullets in a session. Double patterns in one ring will not work potato casting, there is not enough pressure from one potato. A single unit work time is about 2 hours. Multiple rings add little time because you invest and burn them out together. Torching and casting the metal itself when you get to that step is less than a minute with a good multi-orifice gas/air torch. Multiple unit dental bridges were centrifugally cast on other lab equipment, but the potato worked best for little stuff with the finest detail. I also made small silver jewelery pieces occasionally. I tried casting with copper pennies a couple of times for fun but castings came out very bubbly.

I am editing in a safety thing - on the bench against the granite tile on the side toward the person casting was a strip of 1 X 4 wood fastened edge down as a shield for metal splatter. I burned a few spots into it but never got hurt. I wore a big leather apron too. I was so little at 5, I worked standing on a stool at the bench. Reaching into the oven with tongs to grab a hot ring with all that heat coming out was scary till I got confident and could get the oven opened and closed really fast. Grampa was never more than a foot away every time and spent long hours explaining and demonstrating every minute detail because I wanted to learn how to cast. I miss him dearly. That all started very innocently one day when Gramma wasn't home and he needed somebody to sprinkle the flux and then grab the torch so he could pick up the potato.

A copy of this reply has been posted in Casting Equipment as a new thread.

Gary

montana_charlie
12-16-2010, 02:40 PM
I thought I was going to get asked what potato casting is! I'm waiting for you to respond to my remarks about reduction...

lwknight
12-16-2010, 04:23 PM
Well,,, using a potatoe to pressure cast is a new idea for me.
I bet the ancient greeks and romans knew stuff that we never heard of too.

onondaga
12-16-2010, 04:35 PM
I lack a total comprehension of reduction related to bullet alloys. It is not something I have tried to accomplish with 20:1, I generally use alloys with antimony for hardness and less tin. I am anxious to try the dross and tin oxide lump rubbing down the sides of the pot as mentioned in this thread. Never done that. I'd like to see it rise up and just show as ash and have the good stuff go back into alloy. I hope this works for me.

Gary

blackthorn
12-16-2010, 05:34 PM
Quote “Gary,
Can you explain the difference between centripetal and centrifugal forces? I always thought that they were the same thing.

That's an honest question. I'm not trying to break your chops”.

Well---I’m not Gary but---

Cen•trif•u•gal: Pronunciation of centrifugal: \sen-ˈtri-fyə-gəl, meaning: proceeding or acting in a direction away from a center or axis

Cen•trip•e•tal: Pronunciation of centripetal: \sen-ˈtri-pə-təl\, meaning: proceeding or acting in a direction toward a center or axis

lwknight
12-16-2010, 05:38 PM
Gary , it will do it. Its not just automatic or real easy. You do have to work it like you mean business.

Linotype letters have so much surface area that the percentage of oxidation to weight is in my book unacceptable. I would lose like 10 percent if I could not reduce the oxides back in. Like others said , I ended up with just a little carbon dust on top after the wax burned off.

One problem is that more oxides form as you are reducing the lumps.
I would like to have a Pyrex cover for the pot that I could use to seal off the atmosphere and fill the cavity with an inert gas like nitrogen or maybe even argon or helium.

lwknight
12-16-2010, 05:49 PM
Centripetal and centrifugal forces are in effect exactly opposites.

Centrifugal force is the force that flees from the center of rotation.

Centripetal is the description of acting force that opposes the centrifugal force.

Put a rock in a sling and swing it in a circle. Centrifugal force tries to take the rock away.
The strings attached to the sling and held in your hand are what controls the centripetal force , thus preventing the rock from fleeing the centrifuge.

Clear as mud ? I tried anyway.

felix
12-16-2010, 06:01 PM
Yes, they would be the same IN VALUE if the rock in the sling stays the SAME DISTANCE from the center of the circle as the sling rotates with the rock in it. Cannot change sling length and/or rotation speed, or for that matter the weight of the rock without changing one or both of the forces. ... felix

onondaga
12-16-2010, 10:11 PM
The definition you supplied is in exact concordance with the example I gave of stirring the pot of alloy. I don't know if you were confirming my example or questioning my example. The match is there. Maybe you aren't picturing it in your mind's eye if you disagree. I assure you that it fits. I gave a specific example relative to the post where I mentioned the forces earlier to clarify. It is just physics.

Gary

onondaga
12-16-2010, 10:36 PM
An argon atmosphere is not difficult to maintain with a loose bowl over the area you wish to contain the argon atmosphere. The specific tank, regulator, and gas are pretty cost prohibitive however. I have some experience induction casting with Titanium under an Argon atmosphere to fabricate dental substructures and superstructures of implants for crowns, bridges and complete dentures along with hybrid oral prosthesis supported by Titanium implants. That type of equipment is pretty impressive to observe and operate but the Argon is the simplest part of it and actually nothing more than a bowl with a tube supplying Argon over the crucible and induction coil assembly with very slight positive pressure Argon flow. The Argon is necessary when casting titanium as oxidation will be rapid and deeply penetrate Titanium at casting temperatures resulting in dramatic change of physical properties needed for dental implants. Oxides of titanium are also a visual nightmare to aesthetics and the castings will look like badly made Easter Eggs mostly through the entire cast item without the Argon to prevent oxidation.


Hey, R.D.M.
I have a Blackthorn Shillelagh right next to me here that I use! I wonder if you know what that is?

lwknight
12-16-2010, 11:45 PM
I just wanted a clear glass cover on the pot so I could watch it stay shiny.
I have thr flow meter and hoses. Next time I get gas I probably will do something to the atmosphere.

geargnasher
12-17-2010, 01:06 AM
For the record, and this has been debated here before, centrifugal force does not in fact exist. Centrifugal force is called "fictitious force" in physics, and is the necessary opposing force to the centripetal effect, but is not actually a force direction itself. Centripetal force is a vector force where mass trying to move in a straight line is pulled into an arc, centrifugal force opposes this equally, that's how the planets and satallites orbit. The effect of boolit lube being spun off is the product of static inerta.

Now Gary, I'm still waiting, too. Remember, what we call "fluxing" and "reducing" with boolit alloys are really different things chemically, although the terms are generally used interchangeably here. I want to know why you think that elemental tin floats on lead (which it doesn't), and why you indicate that it is impossible for the average caster to reduce oxides back into elements which recombine in the solution, which I am almost certain is easily accomplished with sacrificial reducants. Again, you seemed pretty confident in what you said, but give no explanation.

I snipped some of your comments here, I'm curious what experiences you've had with boolit metals that make you think the things you do. I think the basic problem is that you've never actually reduced the oxides in your own melt because your background was based in fluxing other types of alloys to remove impurities and separate the oxides as waste, and where it wasn't possible or practical to reduce the oxides, and you assumed that the same was true of lead, tin, and antimony.

[Onondaga] "Fluxing of scum doesn't make it disappear. The tin that wasn't fried can be mixed back into alloy if temperatures aren't too high. The centripetal and centrifugal forces of rapid stirring sends some of the fried metal oxides and flux ash to the middle and perimeter of the top of the melt where they can be skimmed. Nothing is disappearing here. Changing and relocating would be a better name for it."

"Tin oxide and lead oxide are molecular substances bonded at the atomic level and not elemental metals anymore . Fluxing will not turn a molecular substance like tin oxide or lead oxide back into their elements of lead and oxygen or tin and oxygen back into elemental metals and free the remaining oxygen. That would be nice but flux won't do that. Flux mainly changes surface tension while having an effect to briefly retard oxidation. Stirring after fluxing will only temporarily redistribute floated up tin and retard it from burning off (oxidizing)..."

Gear

geargnasher
12-17-2010, 01:50 AM
One more thing, I just "phoned a friend" and she said that the final part of the galena smelting process reduces one of the by-products, PbO, into elemental lead and CO2, and CO+heat is used to do it. That would explain why the oxygen-starved smoldering of sawdust or burning oil/wax on the melt's surface aids in reduction of the oxides. Dark orange/yellow flame usually indicates poor combustion due to lack of oxygen, and that is the condition responsible for the excessive creation of carbon monoxide. In the case of reduction of tin and lead oxides, the presence of CO greatly enhances the reduction, and combustion itself is an example of a reduction/oxidation reaction. When in the presence of an active reduction/oxidation reaction (combustion), lead and tin oxides become part of the electron donor process and give up their excess oxygen atoms to the combustion process and the formation of CO2. Carbon from the reducing agent is also consumed here, as well as oxygen from the air surrounding the reaction above the pot. Clear as mud? Me too.

Gear

lwknight
12-17-2010, 03:18 AM
Gear , thats exactly what I have been knowing. I just never could articulate it that way.
Sometimes you just know that what you are reading is in line with what you think you know.
I knew that something had to be actually burning to reduce oxides too. I thought it was just extra heat from the flames plus starving the dross for o2.
This totally makes sense that CO has to be created in order to make the exchange work. And that is why liquid hydrocarbons work so well.

onondaga
12-17-2010, 03:59 AM
You continue to be very enlightening. I have mistakenly transferred some of my precious metal skills to lead based alloys regarding reduction and fluxing and agree with you after so much discourse.

I had believed that fluid tin floats on top of fluid lead when the pot is overheated because the skim from the pot top has changed BHN of bullets from the bottom pour significantly higher in the same pot batch of bullets by observation of my own work checked with the Lee hardness test kit and verified at casting day, then 7 days then 30 days. I deduced the hardness loss as a result of tin loss from the top of the pot. It is just as likely the tinsel fairy changes my bullet density from full to low pot when bottom pouring because I didn't adjust my flow and temperature adequately.

My fluxing technique has been flawed lately due to insufficient heat at the time of fluxing for maintaining low pot temperatures to avoid excess drossing out.

I ran a potful today and made some 340 gr. bullets for my .458 Win Mag Colt Sauer using mystery alloy ingots that were heavily oxidized and they floated a lot of stuff on the melt. Thinking of you I increased the heat to 775 then fluxed with beeswax and lit the flame. A small amount of pale gray powder was all that remained to skim. I didn't skim.,. I refluxed and was able to reduce some of the Gray powder . A third time left even less. Then I skimmed. I think this was successful. I put my thermometer back and covered the melt with Osage Orange dust from my last wood project. I lowered the heat to the casting temp my mold likes and cast the pot without stopping or returning cut sprues. I had good uniformity and initial BHN tests showed no discernible difference from beginning to middle to end of run. 14.1 BHN is what stayed the number throughout at 2 hours after casting. A happy number.

My Plain Base 45 Checkmaker from member PatMarlin should be here in a couple weeks. When I have checks made I'm betting the BHN will have gotten to 17ish that will be fine. Just what I wanted to try some higher pressure loads and bring my accuracy sweet spot from 1610 fps up to a 1900 or 2000 fps for a little more range and flatter trajectory.

If I get a nice day soon I will be casting pure lead round balls for my grandson, He wants to try one of my smoke-poles with patched round balls

Gary.

geargnasher
12-17-2010, 02:41 PM
Gary, I constantly learn from people who know more than I do, and you certainly know your stuff about other types of alloys, I appreciate your sharing that. I thought maybe you knew something else about the lead alloy properties that myself and others had missed, that's why I was drilling you on it.

Your most recent casting experience reflects the way I do it, too, and I have good uniformity start-to-finish as well. If you leave that final application of sawdust just barely covering the melt and cast until the pot is almost dry, you'll likely find very little metal oxide in the remaining ash. Sometimes, with non-critical, plinking-grade pistol boolits, I'll throw the sprues into the pot as I cast, and pause casting every 15 minutes or so to scrape and flux all that oxide back in. Frozen lead is more dense than molten so it sinks to the bottom, and thte oxidized surface of the sprues gets pulled to the bottom where the oxide "skin" can get trapped, so there's the best reason NOT to throw sprues or anything else into the pot in the middle of a bottom-pour casting session. If I don't stir and reduce frequently when returning sprues I get dross inclusions in my boolits, often showing as pits in the surface.

When ladle pouring, I have to reduce and skim about every 15-20 minutes as well since all the ladling activity exposes so much of the melt to air. I wish I knew a way to prevent this, but other than casting in a controlled inert enviroment (i.e. argon/CO2/helium welding chamber) I'll just have to take the time to maintain the alloy.

Gear

montana_charlie
12-17-2010, 03:00 PM
I had believed that fluid tin floats on top of fluid lead when the pot is overheated because the skim from the pot top has changed BHN of bullets from the bottom pour .
Oxides only form on the surface, where the oxygen is, and the tin oxidizes faster than lead.
So, if the surface of the alloy is 20-1, the oxide layer will have a slightly more 'tinny' content...like 20-1.1 and growing. The alloy just below the surface will still be at 20-1 until convection (or stirring) brings it up in contact with the air.
Over time...a long time (or several remelts)...the alloy's lead/tin ratio will probably change enough to be detectable with a hardness tester.

Now that you've tried 'fluxing with fire' you see how you turn scum into ash.
I don't call it dross because I think of dross as an undesirable substance.
Scum contains clean metal that I want back, and 'fire' will do it.

BTW, even 600 degrees is hot enough to 'reduce' in.

CM

geargnasher
12-17-2010, 03:10 PM
Oxides only form on the surface, where the oxygen is, and the tin oxidizes faster than lead.
[snip]
Now that you've tried 'fluxing with fire' you see how you turn scum into ash.
I don't call it dross because I think of dross as an undesirable substance.
Scum contains clean metal that I want back, and 'fire' will do it.

BTW, even 600 degrees is hot enough to 'reduce' in.

CM

Excellent points CM, and it bears highlighting. I meant to mention that, but forgot. All metals that oxidize when heated have an ideal reduction temperature, IIRC iron's is about 300* above melt point, I don't know what 20:1's is but I'm sure it's not as high as 775*. I would think the cooler the better.

It's a common misconception that tin floats on lead since the RATE of oxidation of tin is higher at casting temps than that of lead. Due to this rate, the tin exits the alloy as oxide scum before anything else in the alloy does, so tin is depleted more quickly since tin OXIDE floats on the melt's surface. The higher oxidation rate of tin is due to the fact that it's melting point is so much lower than that of lead. As we know, the higher the temp, the higher the oxidation rate with boolit metal. Tin has a melt point nearly 200* lower than lead (I forget exactly at the moment) and is much more reactive than lead of antimony at casting temps. This also explains why antimony is the last component to oxidize out.

Lead and tin are fully miscible, meaning they form a true solution and do not gravity segregate after being melted together. (sorry for the misspellings, I'm in a hurry)

Gear

lwknight
12-17-2010, 03:16 PM
Gary , the 20:1 will soften with age. I think it might take a couple years but 20:1 will become almost dead soft. Thats what makes antimony so important. The great thing about using the 2-6-92 is that you will see age hardening to about 15 bhn it will remain stable for many years after the initial age hardening.

blackthorn
12-17-2010, 06:27 PM
Onondaga---I was replying to a previous poster's question and so, I was neither agreeing or disagreeing with what you posted, I was simply reiterating the meaning of the two words. My “knowledge” came from something I read somewhere, (and saved) likely from a dictionary, as I seem to recall having asked that question of myself before.

As to the Blackthorn “Shillelagh”,----I believe that is an object made from the wood of the Blackthorn tree, used in a judicious manner to administer attitude adjustments to various forms of pond scum!----No??? (perhaps you use it to cut sprue?)

Have a great day!!

onondaga
12-17-2010, 10:15 PM
That is a creative description of the Blackthorn “Shillelagh”. I'm half Irish and half Sicilian, my parents were both first generation to America. My Shillelagh was my great uncle Mickey's from my mother's side and he carried it the whole length of the Erie Canal as he worked building the Canal. He walked with a bit of a gimp in his old age and used the Blackthorn as a walking aid, but he surely bashed some noggins with it. When he left Ireland all weapons were outlawed for the Irish by England. Men began carrying short Blackthorn billy club type weapons that were quickly outlawed by length although the longer Shillelagh was still legal to carry and became very popular for self protection of the oppressed. Shillelagh are generally lumpy ugly crooked things, and the wood of the Blackthorn tree is much harder than Maple or Hickory and the like. The sharp cut lumps on Blackthorn where the sharp spines were removed with an angled knife cut are very plentiful on a proper Shillelagh and serve to keep it from slipping away to an attackers hands. My uncle Mickey fled Ireland as a wanted man for bludgeoning a tax collector for the crown of England with the Shillelagh sitting next to me . The Blackthorn tree is similar to the American Hawthorn but the Blackthorn has many many more thorns.

Now if you go to Ireland to purchase a Shillelagh, you will notice that tourists usually get the straight ones with only a few lumps because the ones that are crooked with a hundred sharp lumps like my great uncle left me are quite expensive now.

Gary

Mk42gunner
12-17-2010, 10:29 PM
It isn't impractical to make silver bullets, just slow. ...

I am editing in a safety thing - on the bench against the granite tile on the side toward the person casting was a strip of 1 X 4 wood fastened edge down as a shield for metal splatter. I burned a few spots into it but never got hurt. I wore a big leather apron too. I was so little at 5, I worked standing on a stool at the bench. Reaching into the oven with tongs to grab a hot ring with all that heat coming out was scary till I got confident and could get the oven opened and closed really fast. Grampa was never more than a foot away every time and spent long hours explaining and demonstrating every minute detail because I wanted to learn how to cast. I miss him dearly. That all started very innocently one day when Gramma wasn't home and he needed somebody to sprinkle the flux and then grab the torch so he could pick up the potato.

Gary

And I bet Gramma wasn't very happy about it when she found out...

I really don't think I want to try doing potato casting, it sounds like it would be more fun than I really need at this point in life.

Seriously, I have learned a lot from this thread. The term "flux" as it is appllied to bullet alloy has never really made sense to me; coming from a background of plumbing and AC&R repair, fluxing is what you do to clean copper so you can solder or braze two pipes together.

Robert

RobS
12-17-2010, 10:35 PM
My Plain Base 45 Checkmaker from member PatMarlin should be here in a couple weeks. When I have checks made I'm betting the BHN will have gotten to 17ish that will be fine. Just what I wanted to try some higher pressure loads and bring my accuracy sweet spot from 1610 fps up to a 1900 or 2000 fps for a little more range and flatter trajectory.
Gary.

Yes, I'm waiting for my PB 45 checkmaker as well and can't wait to run my favorite 300 and 340 grain PB designs out at GC pressure/velocities.

Echo
12-18-2010, 01:46 AM
Making a person feel foolish, or slightly offended, will often get his attention when 'false kindness' won't.
CM

This old shrink must point out that neither you, nor I, can make someone else feel foolish. We might say, or act, some way to invite that person to feel foolish, or he might interpret it that way, but HE's the one that makes himself feel foolish. A concise, straight-forward explanation is just that. and a mature person will perceive it that way. Our emotions belong to us - no one else can make us feel some way. We do it to ourselves.

geargnasher
12-18-2010, 02:22 AM
This old shrink must point out that neither you, nor I, can make someone else feel foolish. We might say, or act, some way to invite that person to feel foolish, or he might interpret it that way, but HE's the one that makes himself feel foolish. A concise, straight-forward explanation is just that. and a mature person will perceive it that way. Our emotions belong to us - no one else can make us feel some way. We do it to ourselves.

God forbid you go around telling people about personal accountability, they'll get together and pass legislation forbidding you mention it, since it violates their "rights" to blame the rest of society for their problems, and then they'll start taxing food to pay for all the public programs that will be needed to help them cope with the emotional damage you've brought on by advocating emotional maturity. Then you'll get sued into next century by class-action lawyers, but it's ok because Procotor and Gamble will come out with some new shade of neon for a new pill targeting reality-inflicted people, many of which will sue the company for some rare side effect. Heck, maybe it'll stimulate the economy.:hijack:[smilie=1:

Gear