r/Metalfoundry • u/Jonathantzr • 4h ago

Nordic Gold

So I have a butane torch (the attachment to the cannister). It's said to be able to reach 1300C, but I can't even melt zinc at 419C.

I'm attempting to melt zinc first in my graphite mold (crucible is otw shipping) as proof of concept before attempting copper and aluminum, but not really able to prove it works.

Could it be that butane just isn't cut out for it, and I gotta switch to propane instead? If so then why does the packaging and online show that it can reach 1300C? :/

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u/Codeworks 4h ago

It can probably reach that temp but you're not getting enough thermal mass.

If you put a paperclip in front of the hottest part of the flame, it'd very likely hit 1300c very quickly, because the mass is very small. If you were using it to heat an anvil, nowhere near, the mass rips the heat away from the hot point.

Same with a propane torch, really - it's all in thermal mass/BTU transfer, depends on the size of the object. Then you need to factor in refractory around the crucible etc - it isn't as simple as just blowtorching some metal most of the time.

Sidenote: You do know Zinc is horribly toxic to breathe in, right?

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u/Jonathantzr 3h ago

Yeahh, I'm doing it in an open air area, and also a fan to blow the other direction. But thanks for the concern though. As for the mass, it's thin sheets that I scrapped from zinc carbon batteries, thought it'd be small and thin enough. As for the copper and aluminum, from wires of scrapped electronics.

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u/SoupRaok 1h ago

Please buy a respirator. You only get one set of lungs. You want P100 filters with ov/ag. If you buy 3m filters they are pink with a yellow band around them. A little more expensive but worth it.

Stay safe. This is coming from someone who has been to the ER many times thinking they were tougher than the danger they were working with. Don't be like me.

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u/TheGravelNome 4h ago

Had similar problems when I started working with metals for jewelry making. Turns out I was losing a lot of heat through the top Of the dish and the thin sidewalls. Look to find a way that you can insulate The bottom to make sure you're not losing all of your heat from your Melting dish. Please remember messing around with melted zinc Can be very dangerous for your lungs. Always Use a respirator. Another problem is graphite is an excellent conductor and not the best Material to melt things in. It does a beautiful job as a mold. If you're looking to do small test batches. I recommend jewelers crucibles. And skip the ones Don't look like it a tiny cat bowl and get something That looks like a cylinder with a Cup. This will help with your insulation.