test for zinc in ingots

rob bishop

rob bishop

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Melted some w/w down last night and made some ingots. I used a coleman stove and a pot to melt them. I picked through the weights to get out the zinc and steel but i noticed i had missed some steel weights when skimming. Is there any way to make sure i didn't contaminate with zinc? Only made 13 ingots, should i chuck them, or is there a way to check them?

Next time I'm going to carefully pick through them and sort them better. Didn't realize lead and zinc had such a close melting point.
 
JBD said:
zinc has a melting point which is 100 degrees hotter than lead. You should be able to melt it when you cast, flux and skim it off.
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You can't get it all of the zinc that way .. Do some reading on Cast Boolits Fourm .. They had a few threads on removing the last small percentage .. Or diminishing it's effects ..

But a controlled melt will allow you to identify if zinc is there and you can scrape off most of the zinc if it exists ... What is left will still have .01+ zinc content .. Keep adding lead and that can drop lower , but zinc will always be part of the mix.
 
JBD said:
zinc has a melting point which is 100 degrees hotter than lead. You should be able to melt it when you cast, flux and skim it off.
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Doesn't work like that. If it's already been made into ingots then it's already mixed with the lead and it doesn't separate much as it melts - it all melts together for the most part and it's a mess. Ask me how i know - I've got a couple 5 gallon buckets full of zinc contaminated ingots. If you watch closely and use a thermometer to keep the melt temp low then it is possible to skim off the zinc wheel weights when you're smelting, but not after they're already in the mixture.

OP, try the ingots first - you might not have any problem. A little bit of zinc doesn't seem to hurt, just makes really shiney bullets. But my undestanding is that the alloy can only absorb about 1-2% zinc and if you have more than that is when you start seeing the nasty zinc problems. It is really nasty ####, believe me.
 
jethunter said:
Doesn't work like that. If it's already been made into ingots then it's already mixed with the lead and it doesn't separate much as it melts - it all melts together for the most part and it's a mess. Ask me how i know - I've got a couple 5 gallon buckets full of zinc contaminated ingots. If you watch closely and use a thermometer to keep the melt temp low then it is possible to skim off the zinc wheel weights when you're smelting, but not after they're already in the mixture.

OP, try the ingots first - you might not have any problem. A little bit of zinc doesn't seem to hurt, just makes really shiney bullets. But my undestanding is that the alloy can only absorb about 1-2% zinc and if you have more than that is when you start seeing the nasty zinc problems. It is really nasty ####, believe me.
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That's probably what I'll do. I'll mark these ones and try them, If they're no good they'll become a boat anchor. Thanks for the help.
 
Guns guys crave their "Satans": for reloaders it's unpublished loads; for milsurps it's corrosive ammo; for everyone it's headspace; and for bullet casters it's zinc.

I have smelted over two tons of wheelweight in the past 10 years, and have yet to melt zinc into the mix. I don't even try to hand-pick out steel and zinc wheelweights (unless I notice one as I scoop them in).

It's dead easy - mindless really. Add wheelweight, watch them melt and go to a porridge-like slurry, stir, watch, stir, and when it goes clear skim off the steel clips and the unmelted steel and zinc wheelweights, then repeat the process.

Unless you seriously deviated from that approach, I can't see how you'd have zinc in your small batch. It is so easy to avoid melting zinc into the lead that I find it difficult to conceive how anything but gross neglect could cause it.

I have even tried to melt a bunch of known zinc wheelweight into a small batch of lead. I had to crank the heat, leave it so that it glowed pink, and I was just able to do it.

Cast a few bullets and go shooting.
 
This was my first attempt at melting down wheel weights. Some of the stuff you read makes it sound like its very easy to melt down zinc. I just got worried that i missed some zinc weights that had melted in the pot. I did just like you said and skimmed them off just as soon as they melted so it's probably fine. It's just all the horror stories you read about ruining all your lead I guess
 
It glowed pink, huh? Too bad you didn't hve a casting thermometer to see what that melt temp was, LOL

My zinc contaminated lead came already smelted into ingots. Bought it that way. The bad ingots have that flakey look like galvanised tin.
 
It's so easy to find the zinc wheel weights without ever trying to melt them.

I sort my weights before trying to melt them. All I do is drop them on the floor of my shop. The lead weights go "thud" and anything else goes "ping". Simple and effective.

You'll know if you have sink in your mixture when you start casting. Your mold will not fill out perfectly no matter what you do.
 
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