Alloy contamination!

[Chemistross]

I have started casting my own bullets and really enjoy the hobby. I have had great success with making alloys that are the exact hardness I am looking for but ran into something that I can't quite figure out. I was using bullets covered in corundum to lap out a lee bullet sizing die. This worked well and when I was finished with the bullets I tried to remelt them. This grainy looking substance formed in the pot and would not melt. I was able to skim most of it out. My question is what happened and should I try and use the remaining product or just throw the entire batch away? Any advice would be greatly appreciated. Cast on!

[blaser.306]

Any Boolit that I ( you ) have used coated with abrasive of any sort would just get thrown away. The small amount of alloy saved would not be worth chancing contamination of a pot full resulting in a slow, or not so slow lapping / wearing out of a barrel. Just my thoughts and YMMV.

[swheeler]

Flux and stir, all the trash should float to the top.

[bangerjim]

You cannot be talking about very many "sizing" boolots right?

Just throw them away! I would not use any contaminated Pb like that. Just not worth the small cost of a few boolits you cast.

I think you were using "carborundum" abrasive (valve lapping / rock polishing compound)?????? Very hard, very abrasive and could hang around your pot!

Glad you got your stuff sized the way way you wanted!

banger

[country gent]

The corundrum lapping compound is fine abrasive grit ( aluminum oxide or silicone carbide normally) and dosnt melt. The grainy stuff your fluxing out is the grit lapping abrasive with out the carrier ( normally grease or oil sometimes water) Before using this make sure all the compound is removed fluxed out or it will impregnate bullets and they willact as a lapp on the bores when fired. ( think fire lapping ). I would flux several times till this no longer is present. How much lead are we talking about being contaminated? Look at the cost of the lead to replace then the cost of replacing a barrel and or molds and sizing dies. As all will be getting the effects from this grit if not completely removed.

[madsenshooter]

You didn't by chance overheat your pot did you? My Lee pots occasionally get stuck and overheat, and when they do brown grainy stuff grows on top of the melt. Don't know what it is, but it gets hard and won't flux back in.