mystery metal

[rrob692326]

I recently had a problem with some alloy I had. I was given some wheel weight ingots which I mixed with some range lead ingots I bought. When the alloy melted I fluxed as usual but a a large amount of "oatmeal" appeared and floated on top of the alloy. I thought maybe its the tin or antimony so I fluxed again to try to blend it back in, no dice. Then i thought maybe it's in some kind of eutectic phase, so I then tried to raise the alloy temp to 900 degrees still the oatmeal would not blend back into the alloy. Tried casting with the molten alloy and was not getting a good fill on the boolits losing one out of every two to poor quality. I have been real careful over the years as to where and what metal I use so I have never had any real problem like this before. Do you think this sounds like zinc contamination or bismuth or perhaps something else? P.S. I tried melting the "oatmeal" by itself and it did not change from the oatmeal consistency even at 950 degrees I could not get anything to separate from it. The "oatmeal" feels heavy when cool enough to pick up not like tin and not shiny like just melted lead. I'll throw out the alloy of course, but would really like to know what was the problem. Thanks for your help and opinions. Sorry no pictures, I'm kinda computer illiterate.

[1johnlb]

Zinc. You probably had some zinc ww mixed in. Spoon it off and keep casting. If your still having casting problems, you can try copper sulfate to displace the zinc, but you end up with tougher, harder boolits that grow.

There's several stickies on the alloy forum.

[rrob692326]

1johnlb Thanks for your speedy reply and help. Question, why if its zinc, does the oatmeal heated in a pot by itself not liquefy when I subject it to 950 degree heat? Thanks for your response P.S the oatmeal is a dull dirty silver and sorta heavy like lead if its any help.

[1johnlb]

Sorry, but don't know the answer to that. Maybe one of the more experienced will be along soon.

[runfiverun]

bismuth has a low melt point close to tin.
my guess is zinc which does have a higher melt point [787 airc]
the next thing it could be is antimony which should have went back in with the addition of heat and another good fluxing.
the antimony usually is more grey and foamy looking in the initial alloy and is confused with zinc until it goes back in and stays in.

as far as the higher melt point of the slag I would guess you have a lot of oxides on/in the zinc and that will raise the melt point.

I would clean the alloy with some garden sulpher and some skimming, then cut it with known good alloy that should lower the zinc content enough to make the alloy useable without the zinc being a concern.

[Toymaker]

I've seen zinc oatmeal, just skimmed it off and went to work. A couple of times I was casting when it was very windy; my thermometer was also kaput so my temperatures were way higher than wanted. I got oatmeal that wouldn't stop coming. The bullets were much softer than they should have been. Turned out I was oxidizing my tin right out of the alloy.

[Mitch]

you didn't say what temp you started at.could be a bit to hot I have done this and lowerd them tem an got good mix then.say around 700.if that don't work it may well be zn.good luck.i have ner had the need to do an acid test but that may be worth a try there is plenty of infor on the acid test in the stickies here.

[leadman]

If you use some pool acid on the oatmeal (when cool) it will foam up if zinc.