I think I have zinc in the mix...

[Martin Luber]

Fired up the pot with 15# of known good alloy and had room for more. Had some ww lying around, a quick look showed them to be lead, not zinc or steel so I threw them in without looking at all. I figured that any zinc wouldn't melt at 750 F and I could simply skim them later.

I clean with paraffin and what I neglected was it burns and heats the melt. That had melted all in the pot when I came back. But I discovered it wouldn't blend when I went to skim the clips.

I hauled gobs of unmixable metal out. The remaining pot content cast poorly leaving rounded lube groove edges, but sharp bases, even with added tin.

I ran the high volume moulds until an inch or so was left. That, l dumped out the top.

Is that your experience with zinc weights? Is it soluable in lead alloy at 600 F?

If yes, how much is permissible? I have 50# bulk lots of ww l have cast into 10# bars

There may be some zinc there too

[Winger Ed.]

Check out the sticky here about 'A possible way to remove Zinc from molten Lead'

That might fix ya up.

[JonB_in_Glencoe]

I'm not sure what you mean, when you say it doesn't "blend"... "unmixable metal" ... "Is it soluable in lead alloy" ???

What I can tell you is:
Mostly, American WW's that contain Zinc, are pressure cast with ZAMAK 3 (which is about 96% zinc) I mention that only to pass along the melt temp, as it varies from Pure Zinc. ZAMAK 3 has a melt temp of 725º F.

ZAMAK 3 will surely blend in with Lead based COWW alloy.

Zinc contaminated COWW alloy will make lots of oatmeal-like dross at normal boolit casting temperatures, when you scoop out all the oatmeal-like dross, new oatmeal-like dross will form. Depending on melt temperature and Zinc content, Zinc contaminated COWW alloy can cast good looking boolits, but everything needs to be hotter.

[Rcmaveric]

Some people see the antimony separate and think they have Zinc contaminant. Looks similar. Antimony separation looks like soupy sandy like mixture. Zinc look like clumpy sticky cottage chease that keeps forming after skimming.

I personally always separate. I give the steel to a friend that makes knives. I save the Zinc.

I have never seen zinc dissolve into lead. Zinc needs to melt. They dont mix easily and dont like one another. Lead will only absorb so much about 3% at molten pot temps. As it cools excess will precipitate out.

For casting contamination levels. You wouldn't notice .12% to .20% Zinc. At around .5% it starts becoming a major PITA. At 1% dont expect to be able to cast good bullets.

Crank the melt temp up about 50 to 100 degrees and run the mold at almost smoking temps will help.

Hitting a bullet you all ready cast with muriatic acid will tell you it has zinc in it if it fizzes. Flux with sulfur or ZEPP root killer (CuSO4) to remove the Zinc. If using ZEPP use a a couple teaspoon at a time until it stays white. WARNING: fumes and it removes tin from your alloy.

The ZEPP will add copper and give you nice tough bullets. Still needs to be diluted to about .25% copper.

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[Martin Luber]

This stuff floated on top of the lead and stuck to the steel clips.

It appeared to solidify quickly on the spoons.

Thanks

[jsizemore]

I had to learn the hard way not to smelt in my casting pot. Maybe this fits what you did or doesn't.

Take the stuff you skimmed from the top and test with muriatic/HCl acid. If you get bubbling you got the Zn. Could be if it was frothy or gray you might have separated your Sb/Sn and skimmed it from the melt which could explain your rounded corners since of higher lead content.