Rainbow Lead

[Avenger442]

I've been saving up my lead gathered from the scrap yard and processed it this week. As usual, most of it was clip on wheel weights. But I also had some plumbing joint lead (lead ocum joints) and some flashing lead. When I melted and fluxed the lead joint I got a rainbow of blue gold and some red across the surface. Ditto with the flashing lead. I've read what this is somewhere but can't find the location.

All the wheel weight both soft and clip on along with the diver weights were what I usually see when smelted. And I have had lead joint and flashing in the past that didn't exhibit the rainbow.

Can anyone explain what is causing the rainbow?

[ascast]

I think it is very pure, soft. Nice stuff

[daloper]

Pure lead will turn colors on you like that if you get it to hot. It does not hurt it just watch the temperature next time.

[Winger Ed.]

I've seen it too.

Seems like somebody awhile back said it was just the hot lead oxidizing from contact with the air.

[RED BEAR]

Hey its normal enjoy the show.

[Avenger442]

Thanks guys

Wasn't sure that I didn't have a contaminant in the lead. But I couldn't think what it might be. I remember the heat now that I have been reminded. Stuff still had the rainbow colors about two hours after it was cast into ingot. Haven't gone back to look at it to see if the color is still there.

I use a burner off the side of a gas grill outside to do clean up of the lead. It has some adjustment to it. I had it cut back to where I had smelted the lead before. But the temperature of the air was probably higher this time. I'll have to think about air temp and maybe back it down a little next time. I collect stuff from the scrap yard and it sits around until I decide I have enough and want to take the time to process it into ingots. Don't really like cleanup of the lead as much as casting. But it is necessary with scrapyard lead.

[Minerat]

I bought some pure lead from Roto Metal and it came with rainbow colors as an add on!

[rcslotcar]

The colors you describe have always been associated with soft lead when I made ingots.

[bmortell]

yup, I purchased and melted 99.9% pure and rainbows galore, I can even still kinda see it after its cooled.

[Petander]

Yes it's pure lead.

Been there,wondered that,too.

[jsizemore]

Scrape off the surface rainbow and it will be shiny lead. The rainbow stuff is lead too.

[lightman]

I agree with the others. Pure or soft lead that may have gotten a little warmer than necessary. Its not hurt.

[Hardcast416taylor]

Like everybody has said, soft and pure lead.Robert

[Echo]

Lead oxide is blueish purple - tin oxide is golden - don't know about others. Should throw some sawdust in to put the tin back into the alloy. One percent Sn won't affect the Pb much, as far as hardness is concerned, so it's my belief that the alloy has some impurities. shown by the rainbow effect.