Interesting look into a volcano

[armoredman]

So, I get my 10 pound Lee pot into action in the ventilated garage. Actually was better than the back porch, think I'll do this from now on. Four 1 pound ingots dropped in, recast from the last session about 3 weeks ago or so. Melted, fluxed with wax, surface was mirror bright and clean quickly. Good.
Started casting, no issues, good rhythm, havin' fun. After I started building up a pile of sprues, decided I coud see if dropping some in would drop the temp to a point it would affect casting. Nope, not a twitch, so every so often, I'd grab the spoon, scoop up a bunch, and place them, (not DROP), into the melt. Now, mind you, I can't SEE the melt, it's low in the pot, and I am crosslegged on the concrete in front of the pot. I am dropping the sprues on a towel, where some minor wooden splinters dropped from the mold whacker, (unsure what the technical term is), and I scoop them up with an old stainless steel tea spoon. At the end of casting, when the wife says out of the blue it's time to go to PetsMart, ( yep, all done, lemme clean up... :( ), so I look into the pot to see if I should dump into a ingot mold, or leave it.
I am staring into the open cone of an active volcano. Piles of red glowing stone like formations above red glowing lava looking melt, and sparking flashes on the edges next to the pot. ***??!!?!? I know I scraped that puppy clean, and it looked just fine when I put it away AND got it out! I scraped out the slag, and it cooled off to look like sawdust mixed with lead, or something like that, but brown slag. All the boolits came out perfect, no imperfections from weird stuff, but I am very curious what the heck THAT was! The pot cooled off to a sawdust color inside, both on top of the hardened lead, and the inside wall of the pot. What the heck did I do, looked GREAT when I started...
Sooo, how DO you clean a Lee 10# production pot?

[creekwalker]

The "wacker's" called a mold hammer or mold mallet. You've got slag in your pot, was any rust present when you started and how clean was you pot? Also what type of wax did you flux with?

Cleaning options are to add some ingots to the pot and remelt, stir and flux a few times, scrapping sides and bottom to see how much will come to the surface. If your lucky at least some of it will. Next step (sucks) use a power drill with a wire brush in the chuck and start cleaning. Go slow and take your time, wear a good dust mask and either safety goggles or a face shield.

That crap will come out and its a PITA to get it out but kaka happens.

creekwalker

[georgeld]

Just proceed like it wasn't there next time.
Scrape it out as you work. Now and then scrape it out and clear off the floaters,
add a little flux and keep going.

Unless you get inclusions, shouldn't bother anything. Still it looks screwy, I agree there.
Shows what ever it is/was is lighter than the melt as it's floated.

[Blammer]

We need pics!

[armoredman]

If it happens again, I will certainly take pictures, that was the weirdest thing I have seen yet.

[Wayne Smith]

Its probably the result of normal oxidation of the melt. Every time you added the sprues back you added oxygen. Most of that 'slag' is oxidized metal that can be returned to the melt. Your key is the fact that it was clean metal to begin with.

Put more metal in the pot, add your 'slag' from the first, and stir with a wooden stick or add some wax or other flux and stir well. You will find all but a small amount of black/red sand looking stuff will remain, this is almost certainly iron oxide (rust). Scrape it off and go back to casting.

This is why a lot of bottom pour casters put a layer of kitty litter on the top of the melt, it creates an oxygen seal.

Oh, all the pretty colors and such - a result of a hot pot and a little metal, it gets hotter as the level reduces.

[black44hawk]

I have experienced the same phenomenon with the same Lee pot. I've read something in Lyman's Casting Handbook that might have explained it. Apparently dross can become "stuck" against the bottom and walls of your pot by the pressure of the weight of the molten lead. When you are almost out of molten metal the pressure reduces and the stuff floats up to the top. But hey, if your bullets look good then the matter is a curiosity not a problem.