Casting, dross

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fuzz

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Melted a bunch of stick-on WW.
Apparently, 98lead +-2% tin.
Dross forms like crazy. From low to high temps. Immediately after fluxing.
How do I keep that juicy tin in the melt?
Dwayner
 
You mean dross like you throw away or the skin that sort of forms on the top after fluxing?

I'm not an old pro at casting/smelting so take what I do with a grain of salt. I melt all my wheel weights and skim all the clips and garbage. Give it a stir, throw in flux material, stir, enjoy the fire. Stir and skim any crap off that gets turned up. When going to cast, melt lead, flux, stir and skim crap off.

Good enough for the girls I roll with.:) I don't think the layer on top matters after this, IIRC it's a reaction to air.
 
It's still in there. What you're seeing is dirt, burnt sticky stuff, burnt flux, and oxidized lead. Yes, there will be a small amount of tin in there, but not enough to make the slightest difference. The tin in the alloy is in solution, not suspension. If you can figure out how to get tin to separate from lead in a simple melting pot, I guarantee you, you'll be a rich man.
 
Thanks folks.
I misread some reputable sites, the dross is oxides of tin and lead, as you folks stated. Im gunna skim the hell out of it all.
Thanks
Dwayner
 
Fuzz, skimming the hell out of it all (past the initial skim, and a check for zinc or steel parts in the mix) is a bad waste of material.

Leave the oxide skin on - this is why melt pots pour from the BOTTOM, where the metal is unoxidized for the most part. Think of it as 'high-temp plastic wrap' that keeps the rest of your lead 'fresh'.

If you're ladle-dipping, all you need to do is break a small hole in the skin and ensure you don't capture any dross in the actual pour. Hanging off the ladle - fine. Inside the mold - not fine.

Once it forms, the oxidation (for the most part) stops. If you keep skimming, you're just re-exposing your alloy to further oxidation... and throwing out much more lead/tin than you have to!

YMMV, but chemistry is sort of my 'thing'.

-M
 
Thanks folks.
I get a 2.5%+ wt. variance with the bullets dropped from this alloy. Twice as much then from roofing lead and clip-on WW. This made me wonder aboot the dross content.
Ill poke a hole next batch, as directed
 
Are you top-ladling, or bottom-pouring? I assume top-ladling... if so, right after you skim, give the batch a gentle stir and that might help a bit too.

-M
 
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