Fire Scale in Castings

Jewelry Discussion
1

Hi there, thanks in advance for any help!
So I keep getting fire scale / stain in my sterling silver castings which I don’t see untill the pieces are polished.

I cast with my flask at 560 centigrade, my metal at 970 centigrade. Using an open vacuum casting “Kaya cast” unit and an electro melt. I quench the flask after 5 or so mins once the button is no longer glowing red in a dark room.

Any advise on preventing firescale?! What am i doing wrong? See attached photos!

Thanks so much for any help!

2

Lee Epperson developed a way to prevent fire scale / fire stain in castings.

Basically you drop the just-cast flask into a container with a lot of left over wax (I’m sure charcoal would work as well with no burning wax fumes) and put a lid on it.

I’m not sure if a new, clean steel paint can is good enough. You might need to get something fabricated.

Here’s the article:

Neil A

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