Blue/purple film

[omruger]

I melted some lead and it has a blue/purple film on top. Is this a problem or something that is OK to have in the alloy? Is there an easy way to get it back in the alloy? I tried paraffin and sawdust fluxing and neither one seemed to work.

[canyon-ghost]

Is it residue from gray paint on the surface, or temperature related?

If you're melting isotope containers it may be that thick plastic-like paint. If not, might be the lead is pure and way too hot.

[Defcon-One]

Your lead is way too hot! Pure (or near pure) lead will get a film on top that is exactly as you described. Higher temps make it much more of an issue.

Lower your temp to below 700 degrees F and flux then skim off the dross. It will probably take quite a while to come back. At 750 degrees or higher it will come back almost immediately leading you to think that the flux isn't working. It is just oxidized lead! You'll probably see some yellowish scum on the edges of the pot after a while, too.

To answer your question, If you are dealing with pure lead, it is NORMAL.

[runfiverun]

bet they are blue and purplish when ingoted and cooled down too.
you'll most likely see some gold and other colors in this same alloy.
you have pure lead and that's how it goes.
you could flux/skim the entire pot of lead away if you keep doing that.

[adrians]

This is what happened to a melt i started.
My grand-kid must have been playing with the temp control knob a week before, when we were out in the garage getting the mower out ( it wasn't a casting day so the pot was cold).

waaaayyyy toooooo hot....

[wlc]

I've got a pot of lead that looks just about like that. Only thing is mine is from freshly smelted down wheel weights. No SOWW all Clip ons. Will COWW do that as well?

[runfiverun]

the pic adrians shows is completely different.
it is alloy that is too hot and the colors are oxidized contents of the alloy the gold is tin the blue is lead and the purple could be lead or something else in the alloy showing up.
ww's are not just tin/antimony/arsenic.
there are other "contaminants" in there also like indium,cobalt,maybe a little calcite,silver,bismuth, even a smidge of zinc, or whatever.

the colors the o.p. is talking about show up as swirls just under the [what looks like a clear]surface and are more translucent.

[lwknight]

Its normal for pure lead to do that. I try to keep my smelt temp as low as is useful to lessen the oxidation process.
When you melt unknown material strange things happen. Usually you can just cast with it and if it works then all is well , just weird that's all.