Request for Input on Lead Sticking in Aluminum Mold Cavities

[Four-Sixty]

Hello,

I've run into a problem with a new mold again. This is the second time this year. I would like to get input on what may be the source of this issue.

Here is a little history.

The first time this occurred was with a new Arsenal 434-310 RF two cavity aluminum mold. I cleaned the mold with brake cleaner, and began casting. The booits that came out had many dimples in them. It was an unusual effect I'd never seen before. After a couple of tries the problem did not go away. I'm afraid I didn't save any of those to photograph, and in turn show you what they look like. However, when I eventually examined the cavities of the mold I found bits of lead in there that appeared almost like finely shredded foil. They pretty much wiped away with a cotton swab leaving this foil-like debris all over the end of the swab. But, if I recall correctly, I needed a torch to get them all to melt enough to remove them 100%. Also, the problem continued until I later smoked the cavities of the mold which eventually made the problem go away completely. I've used the mold several times since and it has worked just great without the problem returning. So, it appears that smoking the cavities was a work around for this issue.

Today, I opened up a new Lee TL452-230-2R six cavity mold. Because I fell that brake cleaner leaves behind distillates that only contribute to wrinkles, I decided to try denatured alcohol to clean the new mold. There was a fair bit of oil on the top of the blocks, and within the cavities of the mold. I wiped it all away with a paper towel and denatured alcohol and did some other basic prep on the mold. I then set the mold next to my pot to warm up. After I tried casting with the mold, the fill out was pretty poor, so I put it into the melt and got it nice and hot. The first boolits that came out were nice and full, yet very frosty. They would have been useable, but they were too frosty for my tastes. I wanted the mold a little cooler so I set it down for a minute or so and then returned to casting. Upon resumption of casting the boolits, from all cavities, the bullets were dimpled much in the same way as I saw on the previously mentioned Arsenal mold. There was also the foil-like debris in the mold cavities that largely wiped away with a cotton swab. However, I tried casting again and even more debris was in the mold cavities. Also, some of the debris did not wipe away. Spots of lead were firmly fixed to the mold's cavities.

Here are some photos of what I've experienced with bullets from the new Lee mold. Notice that there are dimples in the bullets. (Note: I am aware of the wrinkles from too cool a mold. Heating the mold did not solve the problem with the Arsenal Mold so I did not bother trying that again)

273857 273858

Now, here is the Lee mold before I've removed the debris. Note, I did not smoke the mold prior to casting. I try not to smoke the cavities unless there is some issue with boolit release. If you look at the cavities you can see specks of lead in there. These specks do not wipe away - even when the mold was hot. They are attached to the aluminum pretty good. I was able to remove similar specks of lead from the Arsenal mold by using a torch to get them liquid, then wipe them away. I'll do the same with the Lee mold prior to my next session. I wanted to be sure to photograph the problem first.

The first picture is of both sides of the mold. One is standing atop the other at a 90 degree angle. Notice the debris in the cavities? That is lead adhered to the aluminum. It is more visible in the second photo.

273859 273860

Now, my question is what could cause the lead to stick to the aluminum like this? My hypothesis is that there was something in my alloy, or melt that caused this. I typically use a combination of wheel weights, and reclaimed shot. This particular batch was sourced from a member on this site about a year ago. I've had no issues with it on other molds that have been in use. This has only happened with new, virgin molds. I've enriched that allow with reclaimed shot. That is high in Antimony, and potentially Arsenic. So, I am thinking too much Arsenic could be the culprit. I used this same alloy today to cast with another mold that is well used, and has been smoked. No problem whatsoever! What are your thoughts? How does lead stick to aluminum so well? Has anyone else experienced something similar?

[Teemu]

I always clean every mold same way. First with dishwashing liquid hot water and old toothbrush. Then acetone and last isopropyl alcohol (rubbing alcohol?) . Never had any issues with any mold. No lead sticking like that or what not. And I have quite pile of those.
Some my friends who works with CNC machines advice me to use all those 3 different liquids because some oils etc which are used on CNC machines not necessarily leave without trace if using only break cleaner etc. It just me wondering.. I might be totally wrong.

[tomme boy]

Get that mold up to casting temp and keep it there for about 15min. I use a hot plate. Then take a piece of bees wax and drop it into each cavity that has this. Then take a qtip and wipe out the debris. You might have to do this a couple times. Then before I go to use it I spray it with brake cleaner or carb cleaner, which ever I reach first. Then set it back on the heat plat for a little bit to come back up to temp.

I had 1 mold from accurate years ago that did this very thing.

[TjB101]

I have a Lee 358 SWC mold that is very temperamental. Clean bullets dropping out but I need to smoke the mold a few times each session to help with the bullet release. I keep a candle going next to my station.

Regarding your problem ... if the gunk you showed in the cavity of your molds are burrs causing the dimples I’d try to replace it or use something to lap out those bumps. Also very fine line between too cold of a mold (wrinkles) and too hot (frosted).

Let us know how you make out

[DAFzipper]

More heat!

Sent from my SM-T713 using Tapatalk

[Dusty Bannister]

No mention of what alloy you are using or the casting melt temperature. (725 F ?) I used to smoke the mold to get a sticky mold to release the castings. I do not do that any more. Scrub the mold cavities with hot soapy water to cut the grease and oils. Repeat as needed. Boiling water if necessary. Then the Brake cleaner. Just wiping with a solvent and paper towel does not get the surface fully scrubbed. The oil is released from the pores, then dries on the surface and remains in those dang little lube rings. This does two things, helps knock loose any machine debris, and get down into the grooves of the mold. Preheat several times and try casting after the second preheating session. You need to get the CLEAN mold up to casting temperature and form that protective oxide coating on the mold surfaces. Also any remaining oil debris will off gas and not interfere with mold fill out. If you are not running about a half pot through the mold at a session, you are not getting anything accomplished, just push through and let the mold start working right. Good luck, frustrating, but well worth the effort.

[Four-Sixty]

I should clarify, the debris shown in the cavities is lead that is "soldered" on. It is as if something in the melt acted like a flux to make the lead adhere in specks. Alternately, can one of the oils used in the machining process act like a flux to enable lead to stick to aluminum like that?

I will need to hit the cavities with a torch to soften the attached specks of lead, then wipe them away. I will then probably clean one half of the mold with hot, soapy water. Then, run the mold hot and try it again to see how it works. I'll make sure to get it hot for awhile to 'burn out' any residual residue. I do have that experience with some iron mold blocks.

I wish to avoid smoking the mold blocks for now. I am trying to figure out if the source of the problem is mold preparation, or an issue with my alloy. I hope to try again right after Christmas.

[kreuzlover]

I think DAFzapper has the correct answer. I for one, do not like aluminum molds. I prefer iron molds. Having said that, I have a few aluminum molds and they like to be run HOT! I think that's what the OP should do, turn that heat up!

[45-70 Chevroner]

The only thing I use is to wash with is Comet cleanser using a tooth brush then wrinse with hot water, then wash with dish soap and wrinse again. Let dry or heat it up on a hot plate. I have never had a problem with an aluminum mold sticking.

[45-70 Chevroner]

No! Lead will not stick to aluminum, although lead will sometimes stick to the top of mold under the spruce cutter and I really don't under stand why. It could be because of the friction between the spruce cutter and the top of the mold.

[tomme boy]

use the wax to reduce the lead oxides that are stuck in the mold.

[45DUDE]

Looks like low heat and slow pour. I do about what tomme boy does. I don't clean my molds any more but sometimes I use carburetor cleaner and smoke every once in a while. Some molds need smoke and others not. Depends on the mix --sometimes I have to add a little more linotype to smooth it up.

[DAFzipper]

I've also found that for me no matter how much I clean a mould it takes 3 sessions or so to get a mould casting good. I'm usually using straight WW alloy. I have tin but too cheap to use it. I guess I'm saving it for a rainy day.

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[onelight]

Aluminum molds will make great bullets , I have no brass molds but use aluminum and iron and they all work .
You are getting some good suggestions when I have problems with a mold I have tried most everything suggested and it's hard to say what makes the difference but if you were getting good bullets but frosted with the mold and lead temp hotter shoot frosted they shoot fine , or keep messing with it but it looks like you are not hot enough with the mold or lead maybe both. We don't know what equipment you are using or how close you can monitor temp on your pot . I would say make sure your mix is well fluxed and don't add any culls or sprues back to the pot unless you are getting to low to cast . I keep a clean rag handy if the mold is hot you can wipe a lot of problems out of it or off of it with a rag or has been suggested a q-tip if you do it quickly .
Work with mold and lead hot enough to give you good bullets and then make small adjustments but it may need to cycled a few times to give you perfect bullets.
Hang in there it will work and you will learn what it wants.

[DHDeal]

3 sessions sounds about right especially with a brass mold. New molds are both exciting and a PITA if not cleaned well (and even when cleaned well).

I haven't run into the problem you're having with aluminum molds as anything that might be between the faces wipes off when up to temperature. I would try, if you haven't already, to use a carpenters pencil to scrape it out after heating the halves up. Also, if you think you're having an issue with the alloy, change it out to something else and see. I don't know, but there may be some contaminants in the bottom of your pot if it's a bottom pour and that's flowing into your mold.

I had issues with wrinkled bullets years back and the wrinkles were caused by either a contaminated mold, alloy temperature to low, or mold temperature to low. That's it.

I understand you have another issue with this mold and you've got to get it cleaned off first before moving forward. I'd scrub it with hot water, dawn, and a stiff plastic brush first, then see what will come off with the carpenters pencil. Then I'd heat the halves with cavities facing up on a hot plate where you can see the specks and use the carpenters pencil some more. You can always go Caveman on it to start with, but it's hard to put the Caveman back into the cave sometimes.

[OS OK]

I've bought more used moulds than new and learned a valuable lesson in restoring them to good casting order, aluminum, brass & steel, it's pretty simple but it's a little work too.

First I fully disassemble the moulds, generally every last screw...
put them in the first of three consecutive pots of boiling water. I want all the oils on that mould off and out of the pores of the metal.

*the first gets a few drops of Dawn dish soap & bring the to a vigorous boil for about 10 minutes.
*I put that pan under the faucet and flush the soapy water out and over the rim while the parts are in the pot...I want all the oils to go out over the rim and not have a chance to adhere to the mould again.
*I boil the mould for the sceond time in clean water.
*flush the pot the same way and boil it a third time in fresh water.

hahaaa...they don't call me 'OCD' for no reason but I'm tired of messing with a mould all day that won't cast well & that's the end of that story!

https://i.imgur.com/ecJ6F3t.jpg

Next, I put it in the oven, again for 3 consecutive 'heat treating' bakes. Preheat the oven to 425ºƒ and leave the mould in there for 30 minutes...allowing the mould to cool between treatments to where I can barely touch it, prolly 150ºƒ give-r-take & run it again.
Here I am forming a patina over the pores of the metal, the patina will get even better when your casting. You don't see the patina but it's there & the pores of the metal are sealing off to the boolit metal.
Smoking is never required...ever! hahaaa, that's like 'disrespecting' a proper mould!

https://i.imgur.com/hQEvYYD.jpg

I use parchment paper over a cookie sheet.

https://i.imgur.com/XNqWFYS.jpg

Next is to reassemble and put some lube on the parts even screw threads...I use 'anti-seize', it's made for high temps & it stays put for a long time. It will not migrate into a cavity. Anti-seize is like 'Brylcream' ... hahaa ... "a little dab will do'Ya!"

https://i.imgur.com/TlA9aT5.jpg

Notice that I have sanded the bottom of that old sprue plate flat and have sharpened the sprue cut hole by doing this...I also 'eyeball' that plate from the side to make sure it is flat and not bent from someone whacking it the wrong way. You want good bases on those cast, this is one of those tips that'll get them.

Now your ready to preheat that mould up to around 325ºƒ +/- ... get a hot plate and make an oven for best results. Here I'm OCD again, I want to know when she's ready to rain casts so I monitor the oven temperature.

https://i.imgur.com/mMA80yC.jpg

When done casting I allow the mould to cool some and then brush it down inside and out with some Mineral Oil USP to preserve the steel moulds from rust...WD40 can't hold a candle to the Mineral Oil...when you want to use it again, a quick spraying of the inside of the mould with brake cleaner will have it casting good cast 1'st or 2'nd throw. Mineral oil will not foul the cavity as it will burn off without residue.

https://i.imgur.com/NzgOt9H.jpg

Bring your boolit metal up to whatever temp you desire and go to town casting & enjoying yourself instead of fighting the mould.

That's my story and I'm sticking to it!

[DHDeal]

It's a good story to stick to as it undoubtedly works.

OCD is just being better prepared....

[45DUDE]

OS OK xxx Thanks for posting that. Next time I buy a used mold I will try that if it gives a problem.

[44Blam]

Looks like the mold is too cold when casting... That should go away once you get up to temp.

[oley55]

https://i.imgur.com/TlA9aT5.jpg

Notice that I have sanded the bottom of that old sprue plate flat and have sharpened the sprue cut hole by doing this...I also 'eyeball' that plate from the side to make sure it is flat and not bent from someone whacking it the wrong way. You want good bases on those cast, this is one of those tips that'll get them.



OS OK, a great post on mold preparation.

At the risk of Hi-jacking this thread, I have a question about used molds and a bent sprue plate. A couple years ago I scored 5-358 and 3-429 molds (4-Lee, 3-Lyman, 1-RCBS), a ladle, cast iron pot and ingot mold on a local Gun Trader sight for an unheard of price of $25. Yea a ridiculous score for an, "I'll be a caster maybe someday..." The cast iron molds had some very light surface rust where it counts but seemed to clean up nicely with a lightly oiled rag pushed around with the flat end of a bamboo skewer stick.

I've just recently started playing around and have cast a few using each of the 358 molds with reasonable success for my first try, albeit with a 100% pewter alloy.

I have yet to play with any of the 429 molds. One of them, a Lyman DC, (429215BW) shows light over the cavity furthest from the pivot screw if the plate is lightly tightened to easy motion tension. Totally loose, the plate seems to sit flat across both mold cavities but is really loose with a good bit of up/down slop. It would seem to indicate the sprue plate is bent at or near the pivot bolt.

I have suppressed my usual desire for instant gratification and have refrained from clamping the pivot part in a vise and lightly whacking on the plate with a brass hammer. In your experience should I try to straighten it, flat plate sand it, or is it best to just order a sprue plate kit from Lyman?

[OS OK]

OS OK, a great post on mold preparation.

At the risk of Hi-jacking this thread, I have a question about used molds and a bent sprue plate. A couple years ago I scored 5-358 and 3-429 molds (4-Lee, 3-Lyman, 1-RCBS), a ladle, cast iron pot and ingot mold on a local Gun Trader sight for an unheard of price of $25. Yea a ridiculous score for an, "I'll be a caster maybe someday..." The cast iron molds had some very light surface rust where it counts but seemed to clean up nicely with a lightly oiled rag pushed around with the flat end of a bamboo skewer stick.

I've just recently started playing around and have cast a few using each of the 358 molds with reasonable success for my first try, albeit with a 100% pewter alloy.

I have yet to play with any of the 429 molds. One of them, a Lyman DC, (429215BW) shows light over the cavity furthest from the pivot screw if the plate is lightly tightened to easy motion tension. Totally loose, the plate seems to sit flat across both mold cavities but is really loose with a good bit of up/down slop. It would seem to indicate the sprue plate is bent at or near the pivot bolt.

I have suppressed my usual desire for instant gratification and have refrained from clamping the pivot part in a vise and lightly whacking on the plate with a brass hammer. In your experience should I try to straighten it, flat plate sand it, or is it best to just order a sprue plate kit from Lyman?

That bent sprue plate condition was exactly what I was referring to. It is from hitting the plate slightly upwards as they cut sprue and it bends the plate on the cavity side of the sprue plate retaining/hinge screw. Put that part, just the screw hole in the plate a tad bit deeper in the jaws maybe 1/8" deeper than the hole...then use a soft blow hammer if you have one to lightly tap the center of the plate...tap it close to the vise jaws to bend the plate back to straight. If you get it close you can lay it flat on a good metal surface, preferably a steel surface and tap it flat. Then go after it with sandpaper, I put the sandpaper on a piece of glass, a very flat surface and press in the sprue holes with my fingers and rub it on the 240 to 320 grit, or whatever you have sand paper to flatten and sharpen the sprue cutter. Watch as you sand and you can see if it is truly flat because the new bright metal showing will show evenly across the bottom side of the sprue plate. Where it is not sanding the sprue is high. Doesn't take a lot of work and she's good as new.
After that, when you cut sprue hit down against the sprue plate at a very slight angle so the sprue is forced against the top of the mould as it makes it's cut...this way the plate will not bend again.

This one wasn't bent but I flattened it and sharpened the sprue cut hole by sanding alone.

https://i.imgur.com/DiVcjnE.jpg

It'll look like this all shiny on the botom when sanded.

https://i.imgur.com/KIFhgH2.jpg

[oley55]

thanks OS OK, I'll mess with it tomorrow.

One more quick question on this. I was concerned that sanding the underside too smooth would/could possibly interfere with venting. I'll assume your suggestion of 240-320 grit paper will prevent going too smooth and I should refrain from breaking out my 800-2000 grit papers. :)

[DHDeal]

OS OK's experience is far greater than mine with bringing back old molds, but his flattening appears flat. My molds cast flat bases when the sprue plates are flat and the top of the molds are flat. I also prefer an Accurate Molds type hold down for the sprue plate (Tom's molds are just my example here as others use it). I've modified most of my MP Molds where the sprue plate slides under a screw as a "hold down". I can run the sprue plate looser then.

My point is that I don't worry about venting the top of the mold, have perfect bases, and I pressure cast using a ladle. I pour fast and tend to run a hot alloy around 775° to 800°. I do try to keep my cadence not to fast so I don't get the molds to hot. Venting hasn't been a problem for me with a smooth sprue plate and smooth top of mold. The majority of molds I cast with are either aluminum or brass and I baby them so as to not damage them and want smooth sliding on smooth with lube.

[OS OK]

thanks OS OK, I'll mess with it tomorrow.

One more quick question on this. I was concerned that sanding the underside too smooth would/could possibly interfere with venting. I'll assume your suggestion of 240-320 grit paper will prevent going too smooth and I should refrain from breaking out my 800-2000 grit papers. :)

She'll vent, no problem there.
Have you ever tried to seal off a lawnmower spark plug hole with your finger checking compression? That air pushes out and forces your finger back and exits very easily.

I think of that cavity filling with dense lead and in my twisted lil'mind, it's like that piston coming up, the lead is displacing that air in the cavity with ease. The sprue plate being flat on the top of the mould blocks is nowhere like a good seal.

For proper forming cast bases, you need a hot mould and a hot sprue plate working together allowing the lead to form up tight against the inside top of the cavity, against the sprue plate without chilling and giving you rounded corners on the base.
For a smooth sprue cut you need to wait a couple seconds longer after you see the lead on top of the sprue chill, allow that chill to go deep into the base of the cavity...just a couple seconds does that, then you need a sharp sprue cutter to shear that semi solid lead without pulling lead from the base of the cast.

Don't worry about the venting aspect, go ahead and refurbish the mould as best you can and then use it, cast and discover the cadence you need for the particular mould, the temperature you cast at and the ambient temperature of the place you do your casting.

These casts came from one of those moulds I refurbished, I make it a point to hold the mould up sideways to the light and try to see any light coming through to my eye under the sprue plate on top of the mould blocks. I had none & it wasn't because I tightened that sprue plate down tight, it just lays flat and takes just a little effort to move so it will stay in place as I handle the mould. These casts didn't have any problem venting under that tight fitting plate...the bases are sharp and clean.
You will get the same results...

https://i.imgur.com/fl3y4xv.jpg

[bedbugbilly]

You don't (or I missed it) mention how you cast so I am assuming with a bottom pour pot? Nothing wrong with that if you do as I admire those that can use them - I tried one and went back to ladle dipping.

Your photo of the boolits - as others have mentioned - looks like you mold is too cold and/or your alloy is too cold or a combination of both.

I have a number of Lee molds and some are TL designs. I usually will try a boolit design with a Lee mold if they have what I want thad then will upgrade to a NOE or similar. Anyway - all I have ever done with a Lee mold is to scrub it with soap and hot water, use an old toothbrush on the cavities and then dry it. I have never smoked or used a release agent on any of them and most of my Lee molds - especially the TL designs, drop like butter. I'm talking 2 cavity molds.

I have never used a Lee 6 cavity but am about to try my first one. I'll make this comment and Im not knocking Lee - but I do have a number of NOE multiple cavity blocks - 4, 5 and 6 cavity and all I have ever done with them is a good scrubbing with hot soapy water and a good rinse. The Lee 6 city blocks are nowhere near the volume of metal (aluminum) that a NOE or an Accurate multi cavity mold block is and the more hefty blocks are going to retain the heat better during your molding cadence and casting cycle. If I have a boolit hang up in a mold, it is usually due to the design if it is a deep lube groove pattern. If I do have a hang up, a quick light rap with a wood mallet and they drop.

I suspect that some of your problems are probably due to a combination of things. I am not being critical here at all because we all have had issues over the years and we all learn that some mold blocks pour differently than others. Just going from a double cavity to a 4, 5 or 6 city mold is a learning experience, but, through trial and error, you can eventually figure out what you need to do. As a ladle pourer - I can easily pour a 5 or 6 cavity .225 mold much easier than a 5 or 6 cavity .454 mold because the volume of lead for each cavity is much smaller on a 55 or 68 grains .2225 mold as compared to a 5 or 6 cavity mold for a .454 250 grain mold.

If, for example, you are pouring a 6 cavity Lee mold, and for some reason 1 or more of the boolits don't drop from he cavity when you open the mold, even though it may be a matter of seconds, it taks you time to tap the mold with a mallet to get them to drop. During that time, your blocks are open and they are cooling. I will use a 2 cavity Lee mold as an example. I have probably 3 or 4 of different boolit weights/designs that pour and drop like butter. I run my pot on the hot side and always have for years. I can get a good cadence going and drop a number of them, but at some point, I may start to get some base smear due to a combination of my casting cadence, the heat of the lead and the mold heating up. When that happens, I drop the boolits, leave the mold open and set it on the top edge of my pot (which is hot) and take a short break to maybe take a swallow of water or perhaps like another ingot in the pot and then go back to casting. Even though the blocks are setting on the top of the hot pot - just being open for a moment, they cool off enough to go back to casting and the base smear stops. My point being that some aluminum blocks can cool off just enough between pours if there is an interruption in the pouring cadence and the blocks are open - or they can get too hot if the cadence is too fast and cause a problem.

Everybody does things differently and the secret is to find out what works best for you. If you are confident that you blocks are clean, then look at your casting cadence - how hot your lead is and if it needs to be hotter, etc. I have a 5 cavity NOE aluminum block for a 250 + grain boolit. I love my NOE molds, but when I got it, it drove me nuts. Because of the volume of my ladle, I had to make three pours. I got the temperature of the blocks to where they needed to be, my lead was plenty hot and the block cavities we're spic and span. I tried pouring from the handle end down and I would have one cavity that would give me an issue. I tried pouring from the end and work my way towards the handle. I finally discovered that by pouring the two on the end, then the two nearest the handle and then the one between those pours, all would come out great. By doing it that way, gaining confidence and thereby being able to speed up my casting cadence, I could eventually get to where I was able to keep the blocks hot enough and cast quick enough to really drop them.

It can be frustrating at times - but keep working at it and you'll get it figured out. In over 50 yers of casting, I have only owned one multi cavity brass mold and I never did get the back of using it. I know many like a brass mold but I finally gave up on it and it took a trip down the road. I admire those that have no issues with them.

[oley55]

OS OK, DHDeal,

And to the OP, my apologies for hi-jacking your :oops:thread.

I smoothed the sprue plate and am satisfied I have it flat. Put it back on and still have a gap when tightened down. As the pics show, the area of the pivot looks like it was operated with coarse sand crystals under it, so it's time to smooth/flatten the top of the mold. The edges around the mold cavities have some distortions, but since it is recessed for gas checks I assume any imperfections will be corrected/encapsulated by the gas checks.

How does one go about removing the sprue stop pin? I assume it must be pressed in, but it is not through drilled and can not be driven out (without drilling my own hole from the bottom). Is it a smooth round pin that can be grasped with vise grips and twisted/pulled out?

Thanks in advance.....

[OS OK]

I wouldn't go that route primarily because I don't have the tools to do it without destroying that pin.
I have old Ideals that have the same wear on them...

If it were me...I'd bend that plate a wee-bit more to allow it to lay flat.

[Walstr]

Greetings fellow molder;
My experience with using Lee Aluminum 6 cavity .45 214gr "Cowboy" mold & Clip WW + lil Pewter:
Add sawdust for "flux" & beautiful carbony smoke for mold cavities every 1/2hr or so. Of course arriving at & maintaining suitable mold temperature is establishing my "rhythm" for production.

IMHO your boolits seem 'cool'. Don't worry, you'll figure it out.
273999

Good temps @ Left to hotter temps on the right.

Giving up an sharing other photos, just getting a 'failed to load' msg; maybe too lrg? I was trying to share mold cavity portrait & lrg batch results for you to see % of perfect to icky drops. PM me if you like.

Wally

[GONRA]

GONRA probably missed something here,
but thought Pb (and usual Pb based boolit castin' alloys)
didn't "wet" Al? I.e. would NEVER "stick" to Al?

You experts know the TRUTH here.....

[Four-Sixty]

GONRA probably missed something here,
but thought Pb (and usual Pb based boolit castin' alloys)
didn't "wet" Al? I.e. would NEVER "stick" to Al?

Sir, that is EXACTLY what prompted me to initiate this thread! I've sweat copper pipes, and brass fittings over the years. I'm familiar with using solder flux to get the lead to join the clean fittings. I've be casting for just about ten years now. I have never seen lead stick to aluminum like the two times I have this year. The way it adhered on these two molds reminded me of what I've seen on some plumbing fittings I've done before. So, it got me wondering if there was some element, or contaminate in my melt that was causing the lead to behave this way.

So, I got the chance to cast this morning.

I tried last night to clean the debris still stuck in the mold's cavities. I used a wooden matchstick. The lead that was stuck in the cavities was not coming out. A pencil did the job much, much more effectively, but I was not happy with the amount I was able to remove. I had intended to get that lead debris out, then clean one of the two mold halves with soap and hot water to see what kind of effect it would have. Since I could not get all of the debris out, I decided to get the mold up to temp this morning.

I got to casting like normal, no change to the mold since the first session. The problem returned with a vengeance. I got the mold hot, and hotter, and the problem was still there even the though the bullets were very frosty. The frosty bullets were not deformed, but there was a lot of debris still in the mold after the frosty bullets were ejected. I let the mold cool, and the problem with the dimples returned. So, the very frosty bullets covered up the dimple problem, but did not remedy the problem with the debris stuck in the mold cavities.

So, I got the mold really hot, and tried again. The problem was still there. I was willing to try the soap and water method of cleaning, but since there was so much debris stuck in the cavities, I was concerned I would not get a good cleaning accomplished unless I removed the all of the debris first. So, I just left the mold block atop the melt for about two minutes. After that, I opened the blocks and could see the debris in the cavities was wet and shiny as it was liquid. I was able to wipe it away with a cotton swab. I then thought, why don't I smoke one side of the blocks to see what that does. I did that pretty lightly and cast again. The side which I smoked worked flawlessly! The other half, which I did not smoke, had minimal debris in the cavities. It was certainly less than before. So, I continued to cast to see if it would get worse. After about another two or three casts the problem on the side that was not smoked... went completely away! The mold continued to work fine and I was able to cast up a bunch of boolits.

So, I would surmise, that as others have put forward, there was some remnant of machining oils that just needed to be "baked away", or "cooked off". Had I used the soaps method, the mold would likely have performed properly for me sooner. (I've just always been reluctant to do so as we have very aggressive water in my town that rapidly introduces rust) I still wonder; however; if given a clean aluminum surface if there is some combination of oil, and contaminant in the alloy, that could cause the lead to 'wet' the aluminum much in the way solder adheres to copper. I am still curious about that.

Great inputs folks! Shout out to OS OK for all the photos. Those are always illustrative to folks, and I know it can take quite a bit of time to prepare a post reply.

Thanks folks!

[243winxb]

New Lee Mold - Use a stencil brush & Dawn with hot tap water to clean mold. The Dawn has 5% ethonal in it. Rinse well with the hot tap water. Dry.

Preheat on top of Lee 10 lb pot. Then use maximum alloy, pot & mold heat to start. No smoking mold.

[243winxb]

So, I just left the mold block atop the melt for about two minutes. After that, I opened the blocks and could see the debris in the cavities was wet and shiny as it was liquid. I was able to wipe it away with a cotton swab.

Maximum heat, alloy, pot and mold, fixes a lot of problems.

[Dusty Bannister]

Folks casting with aluminum molds might want to take a look at this thread on the forum.

http://castboolits.gunloads.com/showthread.php?392828-Is-anybody-casting-boolits-from-Zinc

In this thread it mentions that zinc in an alloy can attack aluminum molds as well as steel pot liners. Since this seems to be a problem with new aluminum molds, there must be some benefit in that protective patina that has formed after the mold is broken by heat cycling and casting. Perhaps it results from a very diluted zinc content and the new mold condition that goes away with use. An alloy of clip on Wheel Weights might cast perfectly fine under normal conditions, becomes a problem only when used with a new aluminum mold. Read the thread and see what you conclude.
Dusty

[tomme boy]

It is not lead or zinc. It is antimony and lead oxides. Get it up to temp and use the wax like i have mentioned. The melted wax should reduce it down enough to wipe it off.

[JonB_in_Glencoe]

Yep, like Tomme Boy said, you need to use Beeswax to reduce the oxides and get all the "spots" in the cavities reduced to nothing.
I've done it many times on brass molds, as "tinning" is much more common with brass molds.
Then once clean, I would bake the mold halves (like OS OK shows) a few times, to build up a patina, which acts as a permanent mold release, and retards future "tinning".

[onelight]

Try wax for fluxing your pot also and stir it in well.

[slim1836]

More heat!

Sent from my SM-T713 using Tapatalk

Both the mold and the pot in my opinion.

Slim

[DHDeal]

Glad you got it worked out Four-Sixty. I clean every new mold well with at least hot water, dawn, and a stiff non metallic brush. Preferably I'll use my ultrasonic with HOT water and dawn. Any issues I might have casting will be with a new mold and that will be because of leftover contaminants like oils. An aluminum mold will act right sooner than a brass mold in my experience. 3 sessions seems to be the magic number.

When I started I would smoke a mold and thought that's the way to do it. So many of the casters here stated smoking was unnecessary. But it worked for me I would think. The molds didn't patina, or season and I'd still have little nagging issues. I finally cleaned the molds in question really well, turned up the heat and what do you know, no more issues after a session or two.

JonB mentions tinning of brass molds. I've seen it, I've had it, and I don't like it. I've come to the conclusion that it's my fault when I get it because I'm casting too fast with a hot alloy and hot mold. I find it hard to slow down when the mold is raining perfect bullets, but then I see a little darkness (my description) at the edges of the cavities on the mold face. As long as the mold is screaming hot, a heavy stiff cotton swap and/or a piece of burlap can wipe it off and I follow that up with a carpenters pencil and it's gone. Slow down a little I tell myself as I can have more bullets if I don't have to wipe the blankety blank tinning off of these beautiful mold faces.

[greenjoytj]

A long thread maybe I missed it but I didn’t see any mention of lubing the top of the mold or the under side of the sprue cutter. Lube might reduce the galling on the top of an aluminum mold.

After sanding the bottom of the sprue cutter flat I thought maybe the shiny steel should be blued.
I think the bluing would make a surface that the alloy wouldn’t “wet” to so no tinning on the steel would occur.

How sharp should the sprue cutter be?
The cutter on my new Lyman mold is about as sharp as a butter knife, nice square edges but not sharp like a wood chisels edge.

Never used a brass mold, too afraid I’d get the blocks tinned and soldered together. I understand the need to develop a patina on the brass. Nothing fouls a good soldering job than unclean metal surfaces that won’t wet tin. To speed up the patina how about exposing the brass mold blocks to the sulphur of black powder fouling. It causes a brownish patina to form on areas on the brass elevator in my M73 after one range session before I can clean the rifle the next day.

[OS OK]

A long thread maybe I missed it but I didn’t see any mention of lubing the top of the mold or the under side of the sprue cutter. Lube might reduce the galling on the top of an aluminum mold.

After sanding the bottom of the sprue cutter flat I thought maybe the shiny steel should be blued.
I think the bluing would make a surface that the alloy wouldn’t “wet” to so no tinning on the steel would occur.

How sharp should the sprue cutter be?
The cutter on my new Lyman mold is about as sharp as a butter knife, nice square edges but not sharp like a wood chisels edge.

Never used a brass mold, too afraid I’d get the blocks tinned and soldered together. I understand the need to develop a patina on the brass. Nothing fouls a good soldering job than unclean metal surfaces that won’t wet tin. To speed up the patina how about exposing the brass mold blocks to the sulphur of black powder fouling. It causes a brownish patina to form on areas on the brass elevator in my M73 after one range session before I can clean the rifle the next day.

I had a new Lyman mould and noticed the bottom of the fill holes were almost 1/8" of straight hole leading into the cavity...well maybe 3/32", not sure but it didn't look right to me.
I cleaned and heat treated it as usual and went ahead and cast with it....OMG....it took a considerable harder whack to cut the sprues, they were not 'cutting', they were 'shearing', it looked like it was deforming the base of the cast by pushing that lead to one side & pulling the base from the other as it tried to shear, I could see a hair of a gap & I wasn't having this...I thought that must be an accident that this plate came like this, surely it should'a been drilled to a sharp edge.
I used a diamond grinder cone in my die grinder and had at it....here it is almost ground to a sharp edge as I worked it all the way to the bottom of the plate.
Now, it 'cuts' sprue and takes a lot less effort to whack it.

https://i.imgur.com/J1CRYwg.jpg

[tomme boy]

The brass molds get the tinning from using a high % of tin in your lead. Don't run a tin rich alloy and you don't have to worry about it.