I found a supply of 30 lb lead bars, they have been checked and contain .6% zinc.
Do you folks think this will create problems for casting?
That's an odd alloy - what else is in them, and what were they used for? If the price is good (i.e $1/lb), I'd act on it now. There's a good chance that it will produce good cast bullets, and if not, there's still value in the bars.
^^^ what yodave said,, lead melts at 327C, zinc at 419C so the zinc should float to the top
^^^ what yodave said,, lead melts at 327C, zinc at 419C so the zinc should float to the top
Nice theory, but once the metal is alloyed, it does not work out that way.
Cheers
Trev
The bars are from a medical machine of some sort, $ .90/lb I bought 300 pounds that will do me a while.
I'm going to add tin and try to get it to 4% or 5% so the end result will be approx. $ 1.40 a pound.
For some reason, charcoal in the molten lead makes the zinc float up, making it easier to skim off... That's why I stir the pot with a burning tree branch for about 5 minutes, then skim.
You are presuming it was the zinc that was floating.
My bet. You were fluxing with the wood, the dross floated off, and you were happy, but it wasn't the zinc you were skimming out.
Unless you were doing a chemical content test or metallurgical analysis of one sort or another, it amounts to essentially witchcraft or mumbo-jumbo, as you really have no idea what came out of our alloy and what stayed.
My money is on that the original lead in this post was tested with one of the x-ray guns that Niton sells (~$18,000 per copy) to get the content analyzed. Without one of them, it's all pretty much a guessing game. Or do you have one?
Cheers
Trev
Zinc is the "Great Satan" of bullet casting.
There is an enormous amount of ignorance and fear related to the impact of zinc on bullet alloy, to the extent that there are examples of casters who have discarded huge batches of alloy when they suspected that a single zinc wheelweight might have been melted into it. The worst part is that it requires gross negligence for even one to get melted into a batch - and that's without any pre-sorting. I have smelted (yes I used the "S" word) over two tons of wheelweight and am confident that I have not included a single zinc wheelweight in what went into ingots. In the even that I am grossly negligent while smelting, I know that a small amount of zinc will not ruin a batch.
The "Little Satan" is lead poisoning. We have casters wearing "space suits" and getting their blood tested monthly because they handle lead.
Education is the answer.
If there is zinc in the lead, it will bind the iron and the gold right tight together. However, with no zinc, it would separate the gold and iron quite efficiently... The iron was removed by slowly lowering the temperature, and zinc was used to remove the gold from the lead when the lead had about 1/2 oz / pound of lead in it.
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