Zinc contamination; If you are not sure it probably isnt.

yomomma

yomomma

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Zinc

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First small piece of zinc goes into 1lb of pure lead

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Took a lot of heat to melt it. NO OATMEAL For the longest time it looked like oil drop on water. Had to really work to get it into the lead. Even then there were still little zinc droplets on top of the lead

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On to using wheel weight ingots

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Zinc

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It too floats an like oil drop on water but takes less time to mix with lead

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Oat meal

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Removed oatmeal and cast an ingot, looked normal. Threw back in pot time to add more zinc, two pieces

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Lots of oatmeal

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Bigger pile from double zinc

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Resultant ingot. Yes there are crystalline structures but if you look closely they are very porous.

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The two ingots side by side, 1 lb ingot is the pure mixture.
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3-4% zinc in the mix is not a big issue. If you have zinc contaminated ingots throw some in the big pot next time you process some wheel weights or other lead. Add another 1% or so of tin to help with fill out. Cast and be happy
 
Local plumbing supply store and purchase lead-free solder. Alternately, try local metal recyclers. You can sometimes make some sweet scores of pure lead, wheel weights and tin.
 
Zinc is the "Great Satan" of casting like corrosive ammo or headspace are for milsurps.

Very easy to avoid, and not a big issue if a little bit is encountered. It requires great effort and negligence to melt a significant amount of zinc into a mix.
 
yomomma said:
3-4% zinc in the mix is not a big issue. If you have zinc contaminated ingots throw some in the big pot next time you process some wheel weights or other lead. Add another 1% or so of tin to help with fill out. Cast and be happy
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That's what I do, too. The zinc can actually help prevent leading if you can get it to mix. I usually have to run the pot and mold at higher temp or the zinc starts screwing up the bullets. But they are good bullets when you get them.
 
I deliberately "contaminate" wheel weight lead with a bit of zinc and then "flux" with copper sulfate crystals. When the crystals quit turning brown / grey, and stays white (after it dries, it's blue when put in the melt) I'm done. The copper sulfate reacts with the zinc and copper replaces the zinc in the melt. I now have a copper rich alloy. Doesn't affect the hardness of the alloy much but it makes it much "tougher." Bullets cast with it don't shatter or break when encountering hard objects like steel and bone as standard water quenched wheel weight lead bullets do. Works especially good for tough hollow point bullets.
 
sawzall said:
I deliberately "contaminate" wheel weight lead with a bit of zinc and then "flux" with copper sulfate crystals. When the crystals quit turning brown / grey, and stays white (after it dries, it's blue when put in the melt) I'm done. The copper sulfate reacts with the zinc and copper replaces the zinc in the melt. I now have a copper rich alloy. Doesn't affect the hardness of the alloy much but it makes it much "tougher." Bullets cast with it don't shatter or break when encountering hard objects like steel and bone as standard water quenched wheel weight lead bullets do. Works especially good for tough hollow point bullets.
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That's very interesting - where do you find copper sulfate crystals?
 
jethunter said:
That's very interesting - where do you find copper sulfate crystals?
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I picked it up at my local Co-op ag center. Apparently it's used as a medicine for horse hooves. Was the cheapest I could find locally, no one has stump remover around here and the pool supply stuff is insanely expensive. A tub about the size of a candy tub from Walmart was just over $20 and it's a super fine grind so easy to deal with. Don't have to crush larger crystals. If you want to try this, sprinkle the copper sulfate on the lead and wait for it to turn white before mixing it in. If not the moisture in it will bubble very unpleasantly and you may have a visit from the tinsel fairy.
 
sawzall said:
I deliberately "contaminate" wheel weight lead with a bit of zinc and then "flux" with copper sulfate crystals. When the crystals quit turning brown / grey, and stays white (after it dries, it's blue when put in the melt) I'm done. The copper sulfate reacts with the zinc and copper replaces the zinc in the melt. I now have a copper rich alloy. Doesn't affect the hardness of the alloy much but it makes it much "tougher." Bullets cast with it don't shatter or break when encountering hard objects like steel and bone as standard water quenched wheel weight lead bullets do. Works especially good for tough hollow point bullets.
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Approximately how many pounds of copper sulphate crystals are you adding to each pound of alloy? What percentage of the copper sulphate is converted to elemental copper?

You say the alloy becomes "rich" with copper, but I can't see that process doing any more than adding at most trace amounts of copper.
 
From reading the description of the OP's process, he adds blue copper sulphate to the hot lead and upon mixing a white powder is formed. The inference is that the copper replaces the zinc contamination because zinc sulphate is white.

Let me tell you that the blue copper sulphate also known as blue vitriol is actually copper sulphate pentahydrate. At 110 degrees C it loses 4 waters and at 250 degrees C it becomes anhydrous copper sulphate whose colour is greenish white. A change in colour is expected from the copper sulphate alone. It doesn't necessarily mean that copper has been incorporated. However, zinc is a much more reactive metal than is copper. The spontaneous reaction that would occur is Zn + Cu(+2) -> Zn(+2) + Cu. The reverse reaction is non spontaneous. So thermodynamicly the zinc metal should oxidize to form zinc ions and the copper ions in the copper sulphate should be reduced to copper metal. This is what we want to happen. Mixing is very critical here as the copper ions have to come into contact with the zinc. If left unstirred, the whitish anhydrous copper sulphate simply lies on top of the lead and only a small amount may react at the interphase.

What I make from all of this is the following. A change in colour can not be used as the indicator that copper metal has been incorporated into the lead alloy, but a change in hardness or bullet performance has to be used as the indicator in the absence of a chemical analysis. This is actually a neat way of incorporating copper into the alloy as pure copper melts at 1083 degrees C.

Let me add something useful to this discussion. For every gram of zinc in your alloy you need to add at least 3.8 grams of copper sulphate pentahydrate. An excess would not hurt. Extended mixing of the two layers is paramount.

Peter
 
Nicely done, thank you very much !

Small question about zinc. I have heard where people have casted bullets from pure zinc, have you ever, would they be any good, do any harm ??
 
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