Contaminated Bullet Alloy: The sludge that plugs the nozzle

[nitro-express]

Being new to casting my own, there are a few mysteries about bullet alloy I don't understand, and as I look into the pot I see something is happening, but I am at a loss, I have no idea "what" I'm looking at. I stir the melt and see what looks like Asian Carp swimming under the surface, they are trying to poke their heads through the skim of tin oxide that is floating on the surface.

The alloy in question is a mixture of pure Lead, Babbitt and some other lead like metal and smelted COWW.

I believe the Babbitt is the source of my rogue substance, but a large "Lead" washer that I added to the pot may have been another source.

Bottom line, the nozzle of my LEE pot plugged to the point of requiring a drill to remove the culprit. I bought a new crucible from LEE and proceeded to plug that beech as well. I knew that I had to remove that NPS (Nozzle Plugging Substance) or throw out about 40 lbs of alloy.

I put this project to the side and went onto other things. During a shop clean-up I found a stash of bullets that had been cast from pure lino, by my buddy, many years ago. I decided to smelt them into ingots. They melted nice, and after a flux i was left with a shiny pot of metal, which I poured into ingots. What I was doing was not the problem, what I was doing to my mystery alloy was not right.

I researched and studied, understanding some, learning a bit, but didn't have a definitive answer, and my question was suspect as well. One observation i had; was that if I stirred the pot in a circular motion, the NPS would swim to the center and collect just under the surface. If I scooped this toward the sides it was fairly easy to remove this sludge. In the past I had tried to flux this "valuable metal" back into the melt, now I just kept stirring and scooping out sludge. Call it dross or sponge or NPS, but "valuable metal" it is not.

I fluxed with beeswax and with sawdust and in the end I had a more normal melt. It does cast a reasonable bullet, so although the NPS may be Zinc, I suspect it may be something else. My melt was at 750 F, and the sludge I removed did not melt, and it was still shiny. I collected about 4 > 5 ingots worth of this NPS and when I was done making ingots I tried to smelt it. Surprisingly I was able to melt about 3 > 4 ingots of good metal out of the NPS. What remained was not really metallic in appearance, and I disposed of it. Whatever it was it would bind itself to some of the melt, to form a hard crud, that was particularly well suited to plugging the nozzle of my pot.

In the future I will try to keep my good metal away from suspect stuff to avoid contaminating my melt, and if I notice Asian Carp swimming in my melt, I will fish the beggars out.

Now, on to some of my neglected projects.

And thanks for all the great info on this site, that helped me understand this casting stuff.

Update:

Time marches on and I have used up a lot of the bad alloy. It took a bit of fiddling but I finally came up with a repeatable method of cleaning a pot of alloy.

I melt the ingots and bring the temperature up to 620, the melting point of pure lead. I do not stir or flux, and I try not to get the temperature above 620. Any lumpy material gets removed, in a 12 # melt, nearly 5 LEE spoons full. If I feel that there may be some left, I stir the pot in a circle, anything lighter than the mixture collects in the middle, I remove this also. A quick flux and I'm left with a pot of clean alloy.

I've tested the hardness of the melt, and I don't seem to loose any BHN.

Nitro

[pjames32]

Sounds like it may be zinc contamination. What are you using to flux?
PJ

[runfiverun]

or copper or even nickel.
some babbits contain both of those metals, and some just a bit of either one.

they will both freeze the spout in the same way an over abundance of zinc will.
[you'll still have to watch your boolits hardness after getting the alloy to pour] cutting this 'workable' alloy with some known ww, or purish lead is probably your best bet.

[Yodogsandman]

I had some lead given to me and had the same spout freezing and plugging problem....got rid of it by making fishing sinkers using a ladle, out of it. I figured there was copper in it at the time.

[bangerjim]

When you say "babbitt" it could one of over 30 different alloys all called babbitt!! I have 5 or 6 of them. All are different formulations. Do a web search for the word and be amazed. Unless you have foundry stamped ingots and know the EXACT % make-up, you are stabbing in the dark on Ni or Cu, or other metals that could be causing your problems.

I add no more than .5% Cu to some of my mixes to add "toughness" not hardness. That comes from the Sb. You could end up with a whole bunch more than that with unknown Babbitt alloy.

Flux good. I really do not flux with sawdust in my bottom pour casting pot, but you may have the exception there. I use ONLY beeswax to reduce the Sn back in. A shiny surface magically appears with only a pea-sized hunk.

Have fun in your new casting hobby!

bangerjim

[plainsman456]

For sure there are a lot of types of babbitt,but with the right mix they do make some good tough bullets.

Just take it slow when trying to find the sweet spot.

[nitro-express]

Babbitt can have 5% to 10% copper, and from the junk I removed, that seems to be what I got. To me copper should look like copper plumbing pipe, but that is not what i see. I have some more Babbitt to blend, and I think I'll use the Lyman method of copper removal, if that works, then I at least know what the NPS really is.

bangerjim, I use a plumbers pot for smelting, and pour over to my bottom pour for casing. A liter (quart) of gas goes along way.

[mold maker]

Keep all unknowns separate until you can Id them. Sometimes free stuff that has no Id can cause the loss of a whole pot of melt.
As long as lead is as cheap as it is now, there's no need to contaminate known materials, with unknowns.

[bangerjim]

I too use a plumber's furnace (propane powered) for re-melting. That is where I re-melt and flux 3X all the dirty oxidized stuff I find and I sure do not want that in my 4-20. I also have a small Lee dipper pot for re-melting small quantities of alloy (pewter, etc) to make fractional pound ingots for sweetening my casting pot.

banger

[Handloader109]

Even it the mix has been fluxed several times, I find that every time is melt, there is more dross. Just keep on flkuxing

[gpidaho]

Nitro- I'm right in the middle of getting to know a babbit named Copper hard. This alloy is a touch over 50% lead, 36% tin and 12% antimony and about 1% copper. My first pour out of my Lyman Mag 20 bottom pour was small as I didn't know what to expect. 60 oz. soft lead to 4oz. babbit this worked okay but still wasn't as hard as I wanted. I added another 4oz babbit and this got the alloy to 12-13 BHN but it would no longer work in the bottom pour. (spout freeze) Not to be easily dissuaded as the babbit and lead were both gifted to me, I got out the Lyman ladle, RCBS cast pot and the camp chief propane burner and turned out some pretty good boolits. I had always just used my bottom pour pot before and this was just the nudge I needed to learn to use a ladle. Having the time in retirement to try and make something work that doesn't want to is just part of the fun for me. Now, to see how they shoot. GP

[fredj338]

I NEVER smelt in my pouring pot. This prevents 99% of the problems with plugged spouts & dripping pots. If something does get into the casting pot that starts to sludge the pot, I flux the poop out of it & discard.
I am not sure why you BHN isn't coming up to 12-13. I can get range scrap that is 10, clip ww with less antimony come in around 12. Something isn't checking out there. Lino is 12% antimony & way harder than 15-16bhn??

[gpidaho]

Well yes Fred, the babbit is 12% antimony. So 8oz. babbit should contain 1oz. antimony. When mixed with what is now 64oz soft 60oz. plumbing pipe and 4oz. lead from the babbit I think you'll see what I'm saying. GP

[bangerjim]

Even it the mix has been fluxed several times, I find that every time is melt, there is more dross. Just keep on flkuxing

That is just normal for Sn to oxidize when casting. I always get a bit of oxide on the surface after 15-20 minutes.

Enter the miracle of beeswax!!!

That is why you need to keep your temp as low as possible and use a pea-size of beeswax (ONLY) to REDUCE (not flux) the Sn back. If you just skim your casting pot your are loosing all that good Sn!!!!!!!!

Beeswax smells great, unlike paraffin or candle wax.....(yuck)! And it normally will not flame up. If it does, your pot is waaaaaaay too hot.

Beeswax does not leave hunks of burnt wood to clog your spout. And it WILL somehow get down in there! I fought that for a long time until I switched away from sawdust to beeswax in my Lee 4-20 casting pots. Dust is just fine 3X in your re-melting pot.

bangerjim

[nitro-express]

I believe that copper is the culprit. Today I got tired of looking at the pile of troublesome alloy and did some backyard scientific type experimenting. First I melted some pure lead to calibrate the thermometer I found in my tickle trunk, a CEM 97xx that was not approved for the shop I worked in, so I scrapped it, (took it home). I recorded the lead freeze point, and then mixed in Babbitt to make 16:1 and recorded that temp. I remelted about 30 pounds in small batches, blending to get the same temp as my homemade 16:1.

I varied the temperature from freeze to 700 + and back again. When I passed through 621, lots of floaters, so I assume it was some copper compound. I would skim this, removing a fair amount of "stuff". I then poured this into my LEE bottom pour and poured 4 ingots out, leaving it at least 1/3 full. I repeated this for about 30 pounds of alloy. I fluxed quite often, and when I got most of the stuff removed, it would appear more normal, shiny and smooth. The last 1/3 of a pot of alloy went into my large spoon. It was sludgy and a check of the temperature confirmed that it was too hot to be a pure lead:tin alloy. I then put it and the dross and skimming's back into the plumbers pot for evaluation. Even at "very hot" the alloy was sludgy (still freezing).

I'll use the remaining alloy for casting, and when I see any sludge on the top of the pot, I'll skim and discard it. I don't know what it is, but it's not of any value to me. This stuff does not exhibit typical lead:tin characteristics, so it is disposed of.

I did cast a few bullets, they looked OK, cast fine. I have some lino on order, that I'll add lead to for 92/6/2, with no Babbitt.

[303Guy]

My new alloy which I thought was fairly high in copper and had some interesting characteristics and the first time I cast with it also blocked the nozzle. I cleared the blockage eventually and fired up the pot only to find a terrible sludge like you describe. It wasn't there when making up the alloy. It damn well is there now! Less than half the copper went into the alloy - maybe a quarter. I know this because the copper pieces I thought had dissolved surfaced on skimming the sludge (I'm using the word 'skimming' loosely!) The base lead was sewer pipe. Maybe it's just full of cr@p is you'll excuse the pun.:roll:

I know the nozzle is unblocked because I have the whole pot full on my bench to prove it! :cry:

It's going to be fun extracted the needle file from it! And the pot support post. And the mold. And so on!

Note to self. Don't turn on pot and walk away to put something down then get distracted by phone and forget the damn thing is on! :mrgreen:

[popper]

Felix noted that melting, cooling to slightly above your desired alloy liquidus temp & skim off the 'unknown' works very well. Free copper (greater than soluble amount at solidus) will float on top, skim it off. Works for most higher temp metals. You can use the skimmed stuff as sweatner, if you have any idea what it is. Personally, anything that is spongy or sludgy at 720F gets skimmed off & discarded.

[melloairman]

I have some lead that does the same thing . Between 600-700 degrees the copper and gray colored thick slug floats to the top and gets skimmed off . With a full pot that has the weight to help the flow all is good at 750 degrees . But at about 1/3 gone I have to take the temp to 800 to keep it flowing or the nipple gets plugged . At 800 it still does not drop frosted bullets and the puddle takes a little longer to cool so the cut can be made . But it allows me to use the lead with out the frustration of plugging . BHN ranges between 18-22 according to my Cabin tree .Marvin

[popper]

303guy - interesting. I cast a bunch last nite, 715F, no spout plugging at all. Alloy is 11.5# Isocore (3% Sb, 1% Sn, with the Sn replaced by Cu, shot added for As). Pot down to ~25% added sprue back in and skimmed the grey (bout 1/4 tsp) junk off. New PID probe worked great and I got it connected right the first time - it had no polarity markings. As you said, maybe some 'other' stuff in your lead? You do have a MAPP torch?

[303Guy]

I do have a propane torch which I used to try clear the spout. That spout got red hot and the needle file brought out molten alloy but the blockage was oxide - lots of it.

I'm wondering whether I added babbitt instead of lino. It said 'L' and I've used babbitt before and nothing like this happened before. The amount of copper that did get dissolved is probably a lot less than half the amount I added. How nice it would be to have ready access to an analyzer.

[popper]

Yea, dumped the last out of the pot last nite, mostly clean but lots of blackish, crumbly stuff on the bottom. Spout never did clog. Dumping the hot pot probably oxidized the scum pretty fast on the bottom. Nothing like the bottom of the pot when I recycled 11.5# of HiTek coated. That was a real mess.

[303Guy]

Some feed back. I got the pot spillage away and cleaned out the spout. It was full of oxide, some of it iron oxide. The inside of the pot is full of scale! I wire brushed as much away as I could using my old vacuum cleaner to extract the lead oxide dust.

I managed to break off a few pieces of the spill. Man that alloy is tough! Well, it cast's just fine now that the spout is cleared out. The resulting boolits have a satin surface and those air dropped are harder than my previous alloy and water dropped ones hare still. It's not the copper doing it. I did skim off more of that sludge which does kinda melt with a propane flame. I'm thinking it's a loss and an effort but so what. But the next time I mix an alloy it will not be in the casting pot!

I'm thinking of mixing this new allow with more lead pipe and adding more copper. I'm thinking it has too much tin in it. When the draining ingots freeze there are puddles of molting metal that I think is tin separating.

[popper]

I like to dump the pot to empty, pouring with the drop height leaves a noticeable oxide puddle on the top of the muffin ingot. IIRC, it's supposedly Sb oxide which doesn't flux back in. Same with dumping sprue back in the pot, get a lot of the grey crumbly stuff at the bottom of the pot.

[nitro-express]

I picked up a 20 pound expired propane cylinder and did my "Teddy the Torch" impression on it to make it into a larger batch smelter. I took most of my lead alloy "experiments", about 85 pounds worth, and did a batch. All in all I skimmed off about 5 pounds of metal dross. I prefer clean alloy to maximized Sb or Sn. I re-smelted the dross and poured it into ingots.

My resulting bullet alloy started to freeze at 285 °C on my *** digital and a needle width under 550 °F on my Lyman. I guestimate it to be app equal to #2. I cast a few and they came out on the light side, so I'm not too far off IMHO.

I am a beginner to the cast boolit art, and am still in the buying more equipment phase, (hardness tester, a better thermometer, a bigger bottom flow pot, etc).

I have a few books in my library and I'm slowly digesting the content. There is a sticky on melting temp. and another good tool is a phase diagram, especially for ternary alloys. Lyman #3 Cast handbook has a good section on this. I made an excerpt document and printed it for my casting bench, no computer there.

I had a pretty good idea on the tin content and used the phase diagram and the start to freeze temperature to guestimate the antimony. I ran tests on some of my other alloy mixtures to confirm the results.

I had to study the write-up to understand all the curves in the phase diagram, but the effort was worth it.

I've attached the reprint of the section on the ternary alloy Pb/Sb/Sn.

[popper]

http://phys.scichina.com:8083/sciGe/fileup/PDF/07yg0472.pdf
SbSn is an inter-metallic form. It's structure is very different depending on the cooling rate, it's the structure of the inter-metallic that adds strength, the idea behind 'balanced' SbSn alloys. Works but not the only way.

[williamwaco]

Several members here have access to the equipment to test it for content.

How 'bout it? Anyone volunteer to tell us what this sample contains?

[leebuilder]

I had a similar questionable alloy. I was given a massive chunk of babbit that i could just lift, giggling like a little girl i got it home and rendered down into some usable ingots. I had no way of telling the temps involved but it was higher than COWW. Anyways got some mixed with lead and WW same effect clogging and stringy dross on top of the melt, and it took for ever to soilidify. Could not get it to even go into a boolit mold, just did not want to pour through a small hole. Never touched it since except to pour some diving weight "waffers" for a friend. I fluxed till i was blue in the face, still no success. I am sure this is top of the line babbit, is there anyway to use it for boolits?
Be safe

[Nose Dive]

I too have smelted with babbit. Guy gave me some as he was moving. Scored some 'ingots' from him too. ALL went into the smelt pot [separate ssmelts] and was I glad I did that. His ingots had trash in them and I fluxed four times with Sawdust/Sulfur to get them to brighten up. I have no idea what they 'were' when he smelted them but they were bad news. (i too do not smelt in my casting pot)

I knew the babbit had copper and smelted and fluxed,,,fluxed ....fluxed. Four times again, sawdust and sulfur and borax. It all finally brightned up and I cast ingots and labeled them. Ended up with about 50 or so cupcake tin ingots of the smelted babbit.

So, I thought...what the heck...let's give this stuff a try. I put one of the babbit cup cakes, one of my 50/50 ww/plumber's lead and one of the resmelted ingots into my casting pot. Hit 650,,,all is well....blended it a bit...fluxed with wax once or twice and it all poured out just fine.

So, lesson here is, 'don't look a gift horse in the mouth', but just assume he has bad breath'.....

Nose Dive

Cheap, Fast, Good. Kindly pick two.

[popper]

Leebuilder - maybe aluminum?

[303Guy]

Just thinking, I've successfully dissolved more copper into my alloy than in my last attempt yet I didn't have this sludge/contamination problem. Is the sludge caused by copper? If I recall, my previous alloys were low in antimony. This latest one could be high in antimony. If so, one might suspect that it's a reaction of something with antimony.

[303Guy]

Today I melted down some lead pipe to which I added enough pewter to balance the antimony with tin. No copper added. Well, the porridgy sludge appeared after a while. Now there is still some copper from the pewter but the quantity is quite low but it could still be part of the sludge. I'm going to add some copper to see what it does. The alloy would be 5% antimony and an equivalent amount of tin. The alloy did harden/toughen quite a bit after adding the pewter. I measured the freezing point and got 283 C. According to my alloy calculator the melting point should be 279 C. Close enough.

[leebuilder]

Leebuilder - maybe aluminum?

Could be but it would be alloyed with something, just the temps involed are quite high.
thanks for the input
be well

[popper]

Basically #2 but I've never gotten sludge from real #2. Suspect there is something else in the pipe lead you are using.
Al gets real 'stringy' when close to melt temp. Really hard to cast with it.

[FergusonTO35]

I've noticed the last few batches of range lead ingots I've purchased have more trash in them than previous. I think alot of what I've been getting is copper, if you flux and then let the pot sit for 20 minutes or so it forms a golden brown film on top that can be skimmed off. Alot of your range lead is going to be copper plated rimfire and handgun bullets so I guess that is not suprising.

[popper]

Ferguson - see post #14. Eliminates Cu that is not in solution with other components.

[303Guy]

Just a thought, could it be zinc contamination causing the porridge like sludge? Zinc is after all, slightly soluble in lead and could conceivably react badly to other elements added. Just a thought. I've never had this sludge effect before (then again I haven't exactly melted tons of alloy). Mine started with a new source of lead, that being 4 inch sewage pipe.

[nitro-express]

Time marches on and I have used up a lot of the bad alloy. It took a bit of fiddling but I finally came up with a repeatable method of cleaning a pot of alloy.

I melt the ingots and bring the temperature up to 620, the melting point of pure lead. I do not stir or flux, and I try not to get the temperature above 620. Any lumpy material gets removed, in a 12 # melt, nearly 5 LEE spoons full. If I feel that there may be some left, I stir the pot in a circle, anything lighter than the mixture collects in the middle, I remove this also. A quick flux and I'm left with a pot of clean alloy.

I've tested the hardness of the melt, and I don't seem to loose any BHN.

Nitro

[leebuilder]

I got the alloy tested by a fellow member.
Lead 15.4%
Tin 75.4%
Zinc 5.6%
Copper 3.5%
I may try to dilute it with some tin I have saved up. Maybe not.
Be well

[TexasGrunt]

I'd just use it AS tin.

[leebuilder]

I would love to.
I have mixed it with soft lead (97.5 lead 2.5%tin) a 50/50 mix, like solder. Then mixed a pound of the 50/50 with 20 pounds of WW. Still just grief and stringy mess still won't pour right from the ladle and refuses to go in a mold and though a nozzle.
I have a pile
191668
That's the original ingot I got of the antichrist of alloys. Must be 100 pounds there I can just lift it. I was given two, that one and another that was dead soft lead.
Be well

[TexasGrunt]

That's still a lot of tin in the mix.

For 20 lbs to get 2% tin you would need to add about 8 ounces of the pure. That's off the top of my head.

If that still causes problems it's the zinc levels. Add 1 part bad to 3 parts pure lead. That will get your zinc down to around 1.4%. That amount shouldn't cause a problem from the reading I've done.

[popper]

It's the high tin content turning to tin oxide very rapidly. Try getting the mold hotter and alloy cooler. i've been playing with Pb/Cu/Zn recently, until you add the Zn it pours pretty well (almost like pure). Adding Sb makes it pour better also. Just add more COWW until it casts right.