Lead, Slag/Dross,Boolits, etc...

[ChristopherO]

I've a number of questions that center around the lead, the heavy, thick 'dross' (slag), the differences of how the alloy casts in separate molds. If you will allow, I'll post pictures to help tell the story.
Saturday afternoon I reluctantly began a casting session. I put it off because the 36 caliber boolts can cast fantastic, or terribly peaky. This is a newer aluminum 2 cavity PB/GC mold. The PB cavity will tend to not fill all so well compared to the GC side, but the GC cavity holds them hostage frustratingly tight. I hoped to cast at least 100 of each, but that meant there would be almost twice that many pours to accomplish if this was to be what I've come to expect. (yes, I did everything the mold maker instructs to do. Not knocking the work, it looks wonderful, but the casting sessions aren't enticing) I ended up with 95 of the GC's and 80 of the PB. If I were to be even more picky the numbers would drop even more.

As for the lead, it is Range Scrap I melted into pucks 3 years ago. It isn't necessarily hard, but stiffer than plumber's lead by quite a bit. I've added a handful of monotype into the pot to harden it up a bit, but as the picture shows that all becomes a thick oatmeal mix on the top that has to be skimmed off:
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A goodly pile of waste is then spooned out to harden:
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When that is accomplished the mix is a good melt of alloy that casts well, when all things are as they should be, shoot very satisfactorily and expands in water jugs without coming apart into little shards. Just what I am looking for.
296254

As an aside: when I reached the point of putting the mold down a new to me / older steel 4 cavity Lyman 357156 mold caught my eye in the bucket. I had purchased it last fall at a show and had not used it but only tested it months ago. I didn't have a mallet big enough on hand to cut the sprue and abruptly stopped then. This time, though, I laid down a plank of Hickory to hit the sprue plate wing against and for interest sake I poured the lead into all four holes. They weren't good, as the mold was cold, but they had promise, so I kept it up until all 4 cavities dropped really nice SWC Boolits. It didn't take long, either. This was reminiscent of casting thousands of pure lead muzzleloader slugs with steel molds 30 years ago, which were pure joy compared to my work with the aluminum molds These 357156's were so gratifying that I cast 200 of them, enjoying the session more than I could have imagined.

Once this time of casting ended I added more range scrap to the pot Without any monotype. I am wondering if the oatmeal is coming from the hard alloy or ? I suppose when I heat it up again it will tell the tale. When melting the range scrap into pucks originally there wasn't much dross to deal with, and none that I recall that looked like this mush that comes to the surface.

I keep the Lee 20 lb pot on high in the cold garage (30+F)

I don't think it is zink or the alloy under the slag would be contaminated from everything I've read

If you have any thoughts on this that would be helpful.

[243winxb]

The monotype is listed as having 19% antimony. This raises the melt temperature needed. You need more heat before fluxing & while casting. https://www.thehighroad.org/index.php?media/lyman-alloy-chart.3536/full

[Springfield]

You don't mention trying flux to get rid of the oatmeal. It isn't going to go away on it's own, but it should go away with a bit of proper fluxing at the right temp.

[ChristopherO]

You don't mention trying flux to get rid of the oatmeal. It isn't going to go away on it's own, but it should go away with a bit of proper fluxing at the right temp.

I flux with candle wax before casting. The Lee pot is set on the highest setting, which is plenty hot for the alloy beneath the oatmeal. Must not be for the antinomy within the dross, though, from what 243winxb shared. When the range scrap was originally melted and separated from the jackets it was fluxed with pine shavings from my table saw. Never saw the oatmeal consistency then, but plenty of dust came to the surface that was swept up from the range gleanings. It was well fluxed and cleaned at that time.

I've just plugged the pot in and may cast some more. This time without any of the monotype included. It all gets skimmed out anyway.

Thank you for your input, gentlemen.

[Springfield]

Best to get a thermometer. The only time I have problem with this type of dross is when I let the mix get too hot, then it just won't go back in. So I skim it and try again next smelting session or I just let it cool off and try another day. I have never had it NOT go back the second time if I do my part. There is a window of temp that works the best, too cool or too hot and you are out of luck. For me 700-725 deg. seems to be best.

[megasupermagnum]

I've been down this road before. The yellowish/orange junk is oxidation from overheating. This is also told by the rainbow colors of the dross. Chances are you did as I did, and turned the pot all the way up, which if I recall was in the 950-1000 degree range. I'm not sure what can be done, but I ultimately scrapped the whole pot of lead, and restarted with new. I never could get the alloy clean again.

[JonB_in_Glencoe]

too hot.
fluxing is needed to get all that metal in the dross, back into the melt.

[Rcmaveric]

I would save that dross for the next lead smelting day. I started doing that when i noticed how heavy my dross can got after a while. I was wondering how much I was wasting. So now when i am smelting. My pot hold close to 100lbs. I just dump the dross can into it. Pour in the pine shavings and lot simmer for a bit while i hydrate and poke around. Then flux with with a wax or oil and scrape out the charcoal to pour ingots. I noticed afterwards my discard doesn't weight as much as the dross can. So i know I am reclaiming something. Something is always better than nothing.

Yes back your heat off. I normally cast around 900 and have never seen that happen to me. I have seen similar though from people who leave pot on all night by accident. So i would think it has something to with the antimony seperating out and oxidizing. Antimony is known to follow out of solution and need to be fluxed back in. Tin and antimony oxidze really fast above 700. That yellow skin, thats tin rust.

Sprinkling some borax on top of your pot will stop the oxide by making a barrier. Charcoal (burnt pine shavings or coconut coir) or kitty litter does the same thing. CharcoL has the added benefit of purifying the alloy.

If i am having fill out issues i will run a mold hot and live with frosted bullets. Cavities that dont releasr get their edges checked with a q-tip for burs. If no burrs then i break the edges with a razer (i can explain it needed). Pre heat molds. Honestly i dont own a mallet. I tinker with molds until the bullets drop with a gloved finger tap.

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[ChristopherO]

Okay, too hot, this makes quite a bit of sense. On the newer aluminum 2 cavity mold I have fits with consistent fill out. Some pours have crisp, clean bases when the sprue plate is rotated back, while others want for more lead. Because of this i keep the heat high and live with some frosting to eek out enough keepers before becoming too frustrated putting the rejects back into the pot and walking away. I've tried lowering the temp before and then the classic 'too cold' lines appear in no time. It is such a fine line with these pots. I suppose this is why folks add PIDs to their set up for better results?

This is not a bottom pour pot. A ladle is used to fill the mold, and I don't scrimp when pouring.

Last night I smoked the molds well, again, and started with the newer aluminum two cavity. 23 GC and 15 PB was all I had to show for the effort with many more pours wasted. Then I picked up the Lyman 357156 4 cavity and lost very few once the mold was up to heat, adding almost another hundred to the jar in short order.

Rcmaveric, thanks for your suggestion to take a razor blade to the edges. I've cleaned up noticeable burrs before but will use the cotton swab trick and proceed carefully as necessary. It is a good sight to have the boolits fall from the mold without effort.

[243winxb]

aluminum molds- https://www.thehighroad.org/index.php?media/casting-with-lee-molds.4127/full

[Mitch]

If the range lead melted with no think dross I would think the problem lies in the monotyp.I would try heating the melt slowly and flux it as you go and see if the temp is the problem or try fluxing as soon as it melts.Or try starting over with just your range scrap to take one thing out of the process.My lee pot will melt and cast fine at about a 4 or 5 setting.Your aluminum mold should cast good bullets just like the steel. you may need a bit more heat for the aluminim but by that is on only about 50 deg more.Just because you bought what is supse to be monotyp don't mean that is what it is.You have no cluse what is in it.Just my thoughts here.

You mention a clod mold.you might want to get a hot plate if you do not have one.

you metioned the bullets sticking in the mold this could be from burrs.the temp thing is what bothers me here. the mold will tell you where it likes to cast temp wise.It will stop sticking whenyou find the right temp.I am curious as to how long it take your sprue to harden

[ChristopherO]

You gentlemen's willingness to share and help is a major plus. Thank you again for all the beneficial suggestions. If I start enjoying this process again the television will lack for company.

[gwpercle]

It also is much easier to cast on a warmer day . When it's cold... 30 degrees ... the air just sucks the heat away from aluminum moulds and the pot . Jacking the pot up to high just leads to the oatmeal mush .
You want a warmer day or heater in garage . I cast with the same Lee Pot , but never on high .
I start out on the dial #8 and as things warm up , move the dial back to #7.5 then #7.25 and usually doing most casting on dial setting #7.0 and getting slightly frosty bullets at that setting .
I never cast when its below 50 degrees F ...I don't like the COLD .
Keeping my melt around the 7.0-8.0 setting and fluxing with beeswax and wood shavings ...I've never gotten the Oatmeal Mush .
Good luck , hope these suggestions help ,
Gary

[ChristopherO]

Thanks, gwpercle. I layer up and try to knock my casting out in the colder weather because I'm usually too busy to focus on it when the Spring arrives. But, I can see what you are saying makes sense. I've tried adjusting the pot in the past but it didn't take long for wrinkles to form on the boolits. Yet, I agree, when the volume gets under half way in the pot I believe it may be glowing light red! Yes, too hot is probably my nemesis currently.

[Soundguy]

The oatmeal, assuming no zinc may just bee too cold a mix. I smelted down 900 pounds of mono and lino type last month and that extra antimony does take more heat.

Mold heat cycles will differ with aluminum to iron molds. aluminum heats up and cools down faster.. easy to frost if too hot. ps.. for plinking.. frosted bullets are fine for punching paper. size and lube as normal.

[Hanzy4200]

It looks like it got to hot, and then perhaps wasn't hot enough at skimming time. Definitely save that dross. Toss it in the melting pot the next time you process range scrap. You did do a lot of fluxing when you initially smelted the range scrap correct? There's a lot of crap in those melts.

[ChristopherO]

Yes, I laid on the pine shavings when melting down the range scrap repeatedly. A lot of crap came out of those pots, along with a tremendous amount of dust. It was pretty molten lead when I poured the pucks.