Question about lead fluxing


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mgmorden
July 13, 2011, 04:10 PM
Ok guys - I'm taking my first steps into a casting and have a few questions.

I'm currently working through melting down some scrap lead sheeting into ingots. Most of it has a thin plastic coating on one side which has a bit of paper attached in spots to it.

When I melt it down, this coating basically comes right to the top as visible trash that I can easily scoop out of the pot (I took a drill press to an extra table spoon and made myself a nice little spoon for scooping out that stuff).

Now, I'm fluxing the lead, but I'm not sure how much good I'm doing. I take a chunk of wax from a candle, throw it in the pot, and stir. After a few seconds the wax ignites and I just let it burn off. I then stir a bit more.

Now, here's my question - it seems that no matter HOW much I skim, the lead keeps forming a yellow/brownish film at the top. I skim that up, scoop it out, and it forms right back again. Does this lead just have THAT much trash in it or am I doing something wrong?

So far I've done about 30 lbs of ingots. I hoped to have more of it done by now but melting in this little 10 lbs pot is slow :), and with the heat here its been hard to work up the motivation the get on my long pants and gloves and all. I've gotten most of the obvious trash out of it before it went in there, but I never got it quite down to the point where it wasn't forming that film.

Also, I've been hitting up Youtube for some videos on this, and a lot of people are wearing respirators. There seemed to be a lot of discussion popping up around that, but while I like Youtube videos, I don't always trust the commentators there - I trust people on this type of forum more :).

So, with that in mind, should you still wear a respirator when outside, or is just being outdoors enough to not worry about the fumes?

Thanks.

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Searcher4851
July 13, 2011, 04:25 PM
Outdoors, upwind, I don't wear one.

hdbiker
July 13, 2011, 05:37 PM
flux befor you skim or you could skin off any tin in the mixture and you want the tin. biker

brickeyee
July 13, 2011, 05:41 PM
flux befor you skim or you could skin off any tin in the mixture and you want the tin.

scrap lead sheeting is very unlikely to contain any tin.
Tin is NOT an inexpensive metal (though it is cheaper than a precious metal).

How hot is your pot?

"Plastic" can contain a host of things that may be relatively difficult to remove from the melt completely.

kelbro
July 13, 2011, 06:33 PM
Try some sawdust.

ReloaderFred
July 13, 2011, 06:36 PM
I would suggest using wood chips or saw dust for fluxing. You'll get more smoke, but if you use oak or some other hardwood, it will smell good. What you need is the carbon that's left from burning the wood. The carbon is what mixes the various metals in your alloy, i.e.; lead, tin and antimony.

I've never worn a respirator when either smelting large amounts of lead or when casting. My blood level for lead is well within the normal range (had it tested last year) after casting bullets for about 42 years now.

I do wear safety gear, such as long sleeve shirts, gloves, glasses and sometimes a shop apron. Also don't cast bare foot!

Hope this helps.

Fred

snuffy
July 13, 2011, 06:41 PM
Now, here's my question - it seems that no matter HOW much I skim, the lead keeps forming a yellow/brownish film at the top. I skim that up, scoop it out, and it forms right back again. Does this lead just have THAT much trash in it or am I doing something wrong?

Your technique is just fine! The plastic is mainly made of petroleum, so is most stuff used for fluxing . It should burn off, or it can be used for fluxing the lead. Same for the paper.

That film you see forming is lead oxide. It's a natural thing to happen, any metal oxidizes when heated and exposed to oxygen. It will continue to form as long as the lead is molten. Skimming it off just removes lead, if you keep it up, you'll end up with no lead and a bunch of lead oxide.

Once you finish fluxing, pour your ingots. As for a respirator, if it makes you feel better, then go for it, but it is NOT needed. The EPA has everybody afraid of lead. Lead has to be over 1200 degrees F to produce vapor. Any air movement outdoors will carry smoke away, the absence of vapors leaves you safe and secure.

mgmorden
July 14, 2011, 02:33 AM
Thanks for the advice guys! I'll keep doing what I'm doing then. Just wanted to make sure I wasn't on a wild goose chase.

My current safety setup is a full face shield, a long sleeve shirt, pants, and a pair of welder's gloves. I was pretty sure the respirator was overkill with me being outside but figured it couldn't hurt to check. :)

Just need to get the rest of this stuff melted down so I can start alloying and making bullets instead of just ingots :).

Thanks again.

.338-06
July 14, 2011, 03:17 AM
I've never researched this myself, but I read an article in Handloader years ago that said lead outgasses (becomes a vapor) at 7000 degrees F.

snuffy
July 14, 2011, 11:20 AM
I've never researched this myself, but I read an article in Handloader years ago that said lead outgasses (becomes a vapor) at 7000 degrees F.

Lead boils at 3180 degree F. That's when it begins to vaporize at a high level. Before that from 1200 to the boiling level, minor vapor is released, but it forms a layer that clings to the surface of the molten lead. It's heavy just like the molten metal. Disturbing the surface will make it flow off and fall to the table and floor, but again only over 1200 D-F.

No electric pots get over about 900 degrees on their highest setting. BUT those that cast over a propane burner can get in trouble because there's no thermostat to control the heat and they're capable of easily going over 1200. A thermometer is almost essential to know when you're overheating lead.

No alloy needs to be over 750 degrees F. to make good boolits. Anything over 750 causes tin and antimony to oxidize faster, you'll be loosing those expensive metals through rapid oxidation on the surface of the melt.

GP100man
July 14, 2011, 07:24 PM
Stir while the wax is burning , it introduces carbon into the melt & helps bring impurities to the top !!

The part your skimming off is the lead oxidizing & the purer the lead the qwiker it`ll form.

When I pour from a bottom pour pot I flux with parriffin wax & leave the last fluxing on top to help prevent oxidizing . When working with a ladle I push it to 1 side to dip in a clear spot ,when it builds up I reflux & start again.

But even alloyed lead will do this , it`s a chemical thing with heat oxygen& nitrogen all in 1 place at the same time !

Some will flux back into the melt ,the oxides will look like dust almost.

Wanted to add: I agree with snuffy , working ya lead at the lowest temp possible will help & a good lead thermometer is an invaluble tool in the boolit casting hobby !!!!

Have Fun ,Be Careful !!

243winxb
July 14, 2011, 07:41 PM
I would worry more about the thin plastic coating giving off harmfull gas, more then the lead alloy. A respirator with a self contained suppy of fresh air, like fireman wear, is the only respirator thats going to do any good. imo

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