What is this contamination?

[daengmei]

These ingots were made several years ago and although kept under a roof, were exposed to dust, rain and snow. I used muffin tins and cut aluminum cans. I had just started smelting and used what I thought was enough sawdust and Frankfort Arsenal flux. These were lead roof flashing and then some wheel weights that I did not intentionally mix.


Looks like rust?

[Silvercreek Farmer]

Probably some steel particles that didn't get skimmed out.

[Teddy (punchie)]

lead oxidation would be white , brown or reddish iron .

[Dusty Bannister]

I had a red rust forming in the ingots when I melted and rough fluxed some lead pipe and flashing and poured into ingots. I just wanted to melt the lead down, flux to remove the worst of the trash and make ingots for storage. I always thought it was just the iron particles that I did not flux well enough to remove from the melt. Those ingots look pretty rough, like they were getting a bit cool when you poured the ingots. Melt and flux a few more times and you will probably have nice clean ingots the next time.

[daengmei]

I have been cleaning them again. The first smelting was winter outside and pretty cold. I'm just curious as to how some look really bad and others are still clean looking except for the red impurity. Maybe not till I learned, but I do push the surface aside to get a clean fill to the Rowell ladel, then pour into molds that have been sitting on the hot surface of my setup. The good part is, my initial estimate on weight is very low and I have more than I thought. I've finally used all the flashings, and COWW. Have about 20lbs SOWW to go. Time for the scrap yard tour.

[bazzer485]

Try a magnet, I’m sure rust will stick to
B


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[Land Owner]

I wouldn't worry about it one minute. It is going to come out when you melt it for pouring boolits - as you flux and skim away the dross.

[Lloyd Smale]

got to agree. Not enough there to worry about or resmelt.

I wouldn't worry about it one minute. It is going to come out when you melt it for pouring boolits - as you flux and skim away the dross.

[lightman]

I agree with Land Owner and Lloyd. Not enough reason to remelt them. Just make it a point to flux more or better the next time.

[redhawk0]

Even though its not enough to worry about...its interesting.

Doesn't tin rust? Maybe you have some tin in that mix.

redhawk

[daengmei]

Most were roof flashings but I did have a few 4" sewage joints. That's where the tin came from maybe? I didn't know then to separate any of the joints.

[JonB_in_Glencoe]

Even though its not enough to worry about...its interesting.

Doesn't tin rust? Maybe you have some tin in that mix.

redhawk

Tin doesn't rust. It's actually known to resist corrosion.

[daengmei]

Maybe I need to clean the pot and ladle more often to remove the scale that seems to be always present?

[bangerjim]

Even though its not enough to worry about...its interesting.

Doesn't tin rust? Maybe you have some tin in that mix.

redhawk

Sn (and Zn) are actually used for RUST-PREVENTION on rolled steel! Sn mixes perfectly with Pb and you want about 1-2% of it for mold fill-out. It will NEVER appear as rust. You have some miscellaneous Fe particles in there that floated to the top of your ingots when you poured them. Either skim off when you put in your casting pot, or scrape off deep enough to get rid of them.

Either way you have not problems.

[daengmei]

Thanks for all the help.
Jim

[Alan in Vermont]

I had a couple hundred pounds of range scrap ingots that had that same pox. I wasn't about to sell it in that condition so it all went through the kettle again.

[daengmei]

I've been smelting some of them and in a few months I hope to see clean(er) ingots..

[kevin c]

I get brown spots on my big storage ingots. While there is a little rust on the steel propane tank and the small loaf pans I use as molds, and some on the cast iron Rowell ladle, all of it seems pretty adherent, and I never see any come up on top of the melt, even when I thoroughly scrape down the sides of the pot with a steel spatula.

The brown spots only appear after I unmold the ingots onto the rusty steel panel that I cool them on. They only appear on the high spots on the side the ingots get dumped on, and mainly on the ones I shift around (pushed and slid rather than picked up as they're still really hot).

I figure the still soft lead gets rust particles embedded in it from the scraping over the plate. No worry for me as the storage ingots get remelted, fluxed and skimmed as they're alloyed and remade into small ingots of final casting alloy.