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Was recently given a deep 6" cast iron pot for smelting. The inside walls are caked with a layer of yellow material. This stuff does not melt when using the pot for smelting plumbing lead. Might anyone know what is this stuff and how to get rid of it?
Could be lead oxide scale I would think heating it up empty and the dump cold water in will break most free and the rest will chip off with a stick or spoon
WHOA!!! on the water... if the pot is cast iron the thermal shock will most likely crack it. I've got what was once a nice Grizwold cast iron chicken frying pan that a friend tried to clean the patina off by burning it in his wood stove... would have been fine but he used a water hose on it while it was still warm... it's got a 3" crack right in the center of the bottom... ruined. Turned a $50-$75 pan into scrap. I should throw it away but not before I knock a hole through the bottom... don't want somebody in the future to try to use it and burn their house down.
Try boiling water in the pot. I know guys clean their bottom pours that way. Also a mixture of vinegar and hydrogen peroxide might take it off. Of course you could just ignore it too!
To be clear, that pot was already in use for processing lead when you got it with the yellow stuff inside?
Yellow! It must be GOLD. :popcorn:
Nope. I have panned enough placer to know what gold looks like.
Correct. I plan to try boiling water, vinegar and hydrogen peroxide, although not all at once. This pot is the perfect size for my modest smelting needs.Quote:
Originally Posted by kevin c
If melting lead dosent loosen it i doubt water would touch it never seen yellow lead oxide maybe a mineral like sulfer hey isnt uranium yellow just kidding
Picture of a yellow lead oxide here (other colors are possible too):
https://en.m.wikipedia.org/wiki/Lead(II)_oxide
And it turns out one form of tin oxide can also appear yellow:
https://en.m.wikipedia.org/wiki/Tin(II)_oxide
It's suggested here in this thread that melting pure can give you this:
http://castboolits.gunloads.com/show...adle-weirdness
And here in this thread orange and yellow stuff in a hot pot of mostly lead-tin alloy was analyzed and the conclusion was that it was mostly tin oxides (different lead and tin oxides can range in color from yellow to red to brown to black).
http://castboolits.gunloads.com/show...Lead-Pot/page2
Maybe not definitive (BNE does note the shortcomings of XRF and his own experiences that suggest other possibilities), but at least suggestive.
Please let us know how it cleans up.
And please note that lead acetate, produced by interaction with vinegar, is highly absorbable through the skin and is considered quite toxic.
Kevin:
Thank you for the detailed response.
I would just carry on melting and fluxing with the pot full of alloy then try using a hardwood stick to do a bit of scraping once the alloy is melted. The oxide layer may gradually break up and float off then can be scooped out of the pot.
I get a layer of oxide on my pot but have never seen a thick crusty layer. If it is crusty and hard I'd try a wire wheel on a drill or die grinder or whatever fits in the pot... of course when it is empty and cold.
Be warned that the lead oxides are quite toxic so you should wear eye protection, respirator and gloves when cleaning the pot especially if the oxide is dry and dusty.
If the oxide starts coming off during regular use you will likely get a dry, dusty layer on your melt, just ladle that dry stuff off the top after fluxing each time but again, watch for dust.
baogongmeo:
Before you shoot a hole in that pot you could try brazing it. Brazing rod should fill and join the crack and will not melt at any temperature you will melt lead at. Should make for a permanent fix.
Longbow
Did you get the pot clean? What worked?
Personally I would take a wire brush in an electric drill and remove that stuff. I would exercise some caution such as wearing a face mask and maybe using a fan and staying up wind of it. Or maybe wetting it down and working on it by hand with a scouring pad. But thats just me and its up to you what chances/risk that you are willing to expose yourself to. Then again, it might not hurt anything leaving it in there?
I have see this on i few pots after many lbs of lead.most every old plumbers lead pot are yellow looking.I clened mine buy glass beading it.If you know someone with a sand or glass bead blaster it will take it all out.I would still use a bit of caution as with making any dust from any thing do do with melting lead.A dust mask would be a must.But the wire brush may work just about as well.Might dsepend on how rough the surface or your pot is. nice smooth surface cleans well with a wire brush.
I just saw a special on the restoration of Notre Dame cathedral where they showed footage of the daylight portion of the fire. Every building fire I've seen had dark, almost black smoke, but not Notre Dame's. It's thick smoke was all yellow. I can't help but think the difference was the lead sheathed roof?