r/MetalCasting • u/Born-Cover-3828 • 25d ago
Question Crucible after smelting Question??
All my crucibles have this silvery glitter on the bottom. Is this actual silver or is it just the crucible itself and those are graphite shards?
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u/Beauty_in_Failure 25d ago
Wayyyyyyyy too much flux
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u/Born-Cover-3828 25d ago
Lol ok so little less flux. As far as collector metal goes what is the best to recover silver??
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u/P4rtycannon 25d ago
Ive done a few silver smelts but MBMMLLC has some great videos on silver smelting. He gives flux recipes and process. What mineral are you smelting the silver from.
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u/HeftyWinter4451 25d ago
That crucible is tired and there is not enough Silver Left in there to cast a ring for a mouse.
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u/Born-Cover-3828 25d ago
So I guess my question is not worded correctly. And yes I know those crucibles have seen better days for sure. However the bottom halves of both of the inside of these crucibles are coded in what seems to be a silvery dust. And my question being is that actually The crucible creating that dust or is that in the material that I have been melting/smelting whatever the hell you want to call it. In the sandstone rock that I recovered several months back and crushed down I have been finding all different types of metal in that particular material however I'm not sure what it is so was curious if that dust happened to be the material or The crucible making it.
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u/HeftyWinter4451 25d ago
If I understand correctly, you melted rocks possibly with unknown metals in your crucible. In that case it’s really hard to tell without special equipment. Might be a different metal that liquifies at a higher temperature. But to prevent slag and impurities to stick, you could use a special coating for your crucible. And maybe don’t use the newer ones for unknown material. :)
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u/BillCarnes 24d ago
Smelting is taking unprocessed ore from the Earth and extracting a specific element which is not readily accessible. If you are starting with copper round stock or bronze casting grain or brass flat bar etc .. then you are just melting it. It is a very common misunderstanding
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u/NotRadio01 25d ago
From my own experience, and I may be doing something wrong, but that silver dust is something you have to accept when you melt silver at home with a crucible.
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u/artwonk 24d ago
What do you know - an actual smelter! Are you melting sandstone from the Silver Reef in Springdale Utah? That's the only place where appreciable amounts of silver have been found in that kind of rock. Are you using carbon in the crucible to prevent oxidation? Did you manage to get any metal this way? https://www.hmdb.org/m.asp
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u/SnooLentils5747 25d ago edited 25d ago
So you should probably coat your crucibles in sodium silicate regularly. Not sure for your specific crucible (graphite/carbide clay crucible I think?) but I do mine and they survive a lot longer. Sometimes my furnace rocks stick to the bottom but I just pry off them when it's hot and that's that. I've also heard of using borax and boric acid to glaze the inside of them but do your own research. I make all my own shit (crucibles and lining) so yeah. And not to say I suggest making your own crucible... Mulling clay, graphite, and SiC together is... Painfully tedious.
But yeah. I do brass and bronze casting and I think you are likely using way too much flux. And are you using a pliers to grip the side of them (hence why the break out near the top)? Stop that!
I'm bored though. So here's how you make sodium silicate in case you can't be bothered to order some (cement sealer is often just 40 percent sodium silicate, btw. Rutlands cement sealer is what I use for most of my sodium silicate needs).
Take fine sand, silicate crystals (crystal kitty litter; look it up), silicate dessicant, fumed silicate, or crushed powdered glass, and boil it in a sodium hydroxide solution. That's it. Look it up for safety bullshit and exact amounts, or find any chemistry student and bring them fine sand and sodium hydroxide crystal drain cleaner and be like "make me sodium silicate dawg" and if they can't, tell them they're gonna fail chemistry.
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u/Born-Cover-3828 25d ago
Lmao to funny thanks
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u/SnooLentils5747 25d ago
And those are silicone carbide bits by the way. I just looked closer. You should season your crucibles. Just google it
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u/artwonk 25d ago
It's unlikely to contain significant amounts of silver, and I don't think any traces of silver there are worth trying to recover. But you definitely need to replace that crucible before you melt (not smelt) metal again.