Unusual melt?

[Rock]

Acquired a sheet of lead shielding that was encased within sheet metal. We removed the sheet metal using hammer and chisel and then cut the 100 lb sheet into quarters using a very large chisel. Hammered the quarter into a semi-circle and stood it up in the cast iron melting pot and cranked up the heat.

When the melting began a small amount of lead ran to the center of the pot and became very hot, glassed over with a rose colored film that when disturbed broke like thin glass. When left alone orange transparent globes formed beneath the skin and then popped thru the skin where they remained raised above the skin.

What do I have here?

[sagacious]

Acquired a sheet of lead ... stood it up in the cast iron melting pot and cranked up the heat.

When the melting began a small amount of lead ran to the center of the pot and became very hot, glassed over with a rose colored film that when disturbed broke like thin glass.
...
What do I have here?

You have way too much heat. Not likely to be anything unusual otherwise.

If you crank up the heat waaaaay hot, the lead will turn purple and develop an oxide skin, which is what you saw as the rose-colored film. If you crank the heat up even more, the oxidation reaction with oxygen in the air can lead to actual incandescent burning of the lead. That's what the orange spots are. If you crank up ther heat even further, the lead will glow orange hot and you can actually see it vaporize into a whitish Pb + PbO vapor.

Reduce the heat, try again, and you should get more usual results. With pieces of thick lead sheet, only a small bit of it is in contact with the cast-iron pot. That lets the pot get waaaaay hot before the lead melts, and that's why the initial little puddle got overheated immediately.

Heating the lead too hot can lead cause huge losses to drossing. It's like baking a cake-- just enough heat gets it, too much does not.

Good luck, and stay safe.

[lwknight]

Its probably the glue that bonded the lead and steel together. Remelt it and skim off the foreign stuff.

[docone31]

Looks like someone ate jalepeno peppers and had a rough morning.
Montezuma's Revenge!!!!

[Rock]

Sorry, this was clean sheet lead, no glue, no paint, no other finishes present.

[wiljen]

It wasnt clean lead looking like that, it was mixed with something. It almost looks like you've got some kind of fiberglass mixed in with it.

[sagacious]

It's just plain ol' lead. If you get lead that hot... that's what you get.

The last time I saw lead that looked like that (exactly like that), someone was trying to alloy lead and copper the wrong way. A lot of folks won't have enough foundry experience to know what happens to an excessively overheated melt, but that photo offers a good idea about it.

Unusually hot melt, that's for sure, but not likely an unusual alloy.

Stay safe.

[Suo Gan]

It might have been coated with something? I get plenty of lead that has a coating from the medical industry. Whatever it is they coat it with will blow half your brain cells if you get downwind. But it do make fine boolits when mixed with ww alloy tho.

[Rock]

Regarding temperature: The cast iron pan was glowing a dull orange from the heat of the burner as we tried to get the 25 lb sheet of lead up to melt temperature.

[sagacious]

Regarding temperature: The cast iron pan was glowing a dull orange from the heat...

There ya go. From the photo, that had to be the case. Far too much heat is the culprit.

A big chunk(s) of lead will usually not have much contact with the melting vessel, and so the melting vessel itself absorbs most of the heat. Because of their size, large lead chunks melt slowly, but since so much heat is being directed into the melting vessel, the melt will usually stay overheated during the entire process-- even once all the lead has finally melted.

When melting a large piece of lead in a pot over a gas flame, it's usually a good idea to toss in a few smaller pieces of lead totalling a few lbs, and allow those pieces to melt first. That melted lead in contact with the big lead chunk will in turn provide better thermal contact with the pot, and help equalize the vessel and melt temp while the larger pieces are melting.

Melting 25lbs of lead is a process that just takes time-- take it slow and let it take the time it needs. More heat is not always better than enough heat. The melting vessel does not need to be red hot. A fairly small gas flame will usually do, too large a flame will easily overheat the melt. Good luck.

[zuke]

looks like someone ate jalepeno peppers and had a rough morning.
Montezuma's revenge!!!!

*****!!!

[hammerhead357]

If the pot was glowing it was way, way to hot. There is no need for that much heat ever. Slow down and do like was suggested add smaller pieces to get a pool of lead and then add the big chuncks...Wes

[daschnoz]

Get one of those hand held propane torches and use that to help melt the 25# chunk into the pot.

Set the burner heat to a temperature maintenance setting rather than a preheat/melt/balls-to-the-walls temperature.