Yellow sulfur looking substance ?

[capt.hollis]

I have certain pieces of lead that when melted down a yellow sulfur looking substance comes to the top of the pot . It's lead that I had bought from a scrap metal yard here locally. My other lead ingots do not make this yellow crud looking stuff ? Anyone know what this is ? Lead oxide ?
Thanks a bunch guys.

[lwknight]

Just lead oxide.
You can reduce some of it back in but its a hassle so for me, I just skim it off
and keep on trucking.

[capt.hollis]

Just lead oxide.
You can reduce some of it back in but its a hassle so for me, I just skim it off
and keep on trucking.thank you sir

[sixshot]

This can also show up if you're running too hot.

Dick

[bangerjim]

Skim and cast.......shim and cast! Oxide of Pb.

banger

[capt.hollis]

Thank You guys . It was a concern of mine . Is this stuff very toxic?

[dbosman]

Dispose of very carefully. The oxides are, in addition to contaminants that fume, the most dangerous part of casting. Way, way ahead of the tinsel fairy.

[lwknight]

The oxides can be problematic because powder can become airborne
and also more easily ingested from handling.
It is heavy so it will not just float up without strong moving air
currents.

[bangerjim]

Yes.....as stated above, Pb oxides are very nasty and hazardous to life. Dispose of carefully. And do not breathe it.

Funny.....lead oxide = deadly compound. Zinc oxide = sun block and diaper rash ointment!!!!

Don't 'ya just luuuuuuuuuuv chemistry?

banger

[capt.hollis]

ok, Thanks a bunch guys. yes that stuff looks nasty. Does certain lead have more than others? I think I possibly got this pot too hot while I was melting the pot down before I started casting.

[lwknight]

I had a roll of roofing sheet lead that had a huge hole rotted in it. It was red and yellow oxide.
I tried reducing the red/yellow crud but not much luck. Some things just get it from probably storage conditions. Weird thing is that some lead can exist with only surface grey for many years out in the weather and other things corrode and just flat rot. Its all the same pure lead.

A clip from wiki:
Water in the presence of oxygen attacks lead to start an accelerating reaction. The presence of carbonates or sulfates results in the formation of insoluble lead salts, which protect the metal from corrosion. So does carbon dioxide, as the insoluble lead carbonate is formed; however, an excess of the gas leads to the formation of the soluble bicarbonate; this makes the use of lead pipes dangerous.[11] Lead dissolves in organic acids (in the presence of oxygen) and concentrated (≥80%) sulfuric acid thanks to complexation; however, it is only weakly affected by hydrochloric acid and is stable against hydrofluoric acid, as the corresponding halides are weakly soluble. Lead also dissolves in quite concentrated alkalis (≥10%) because of the amphoteric character and solubility of plumbites.[11]

Anyway from all that I can find to read up on says just skim it off and keep on trucking.

[RogerDat]

I'm posting on this old thread because I was casting some lead/tin alloy and got sidetracked for a bit. Pot is pretty hot with that alloy and I came back to a thick crust on top of the lead. Yellow with touches of black. Looked sort of like thick orange/yellow rust. I tried a bit of crushing with stir stick and then recalled this stuff might be lead oxide so instead of pulverizing I just scooped it out with a spoon.

One nice thing about ladle casting is I don't have to worry about dripping bottom pour making a mess when I'm not looking. On the down side I can leave for too long.

I did add a touch of tin back in because tin will form oxides easier and faster than lead so I figured I had lost some tin. Went on to make some lovely .360 hollow points. I did end up turning the heat down a bit too. I was having to skim about every 10 bullets from a 2 cavity mold.

[kevin c]

RogerDat, did your crust look like the pics in this thread (1st and 14th posts)? This guy was probably running a really hot pot. The thought there was that maybe the oxides were of tin rather than lead.

http://castboolits.gunloads.com/showthread.php?401414-Weirdness-in-my-Lead-Pot