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Can anybody help me with carbon removal? There must be a product out there or technique to remove the carbon deposit left by a blow pipe. I've tried tumbling but because of the concave depression it didn't work. Does anybody know anything about the gray carbon deposit left behind - in warm glass slumping besides color how does the carbon affect the glass?

consider sandblasting the carbon off. At fusing temperatures, the carbon burns off completely... it may be burned off at slumping temperatures as well (~1200°) but I'm not sure of that.

Tony

I've been using this glass in a crucible and had always wondered if the carbon deposits were visible or had burned out upon reaching temperatures of 2000 degrees +. So from my understanding from Tony's post is that carbon disipates?

from my understanding from Tony's post is that carbon disipates?

Not necessarily... I am not sure what the physics are here...but when using a crucible in a firebucket, I got these lovely striations of carbon in the glass I poured. The glass was melted in a clay crucible, and the glass was filthy. I left it all cruddy to see what would happen...and I liked the result plenty. I did several batches...with and without crud. The dirty glass always ended up with these carbon stain striations (maybe it isn't carbon...but I think it is)...cleaned glass was clean. I believe it doesn't fire off because it's actually been incorporated into the body of the glass before it can burn off.

In fusing, if it's a surface discoloration, it can be blasted or ground off then fired back up to smooth...but if your stain is encapsulated...it's there for good. Or so this is my experience.

I've had exactly the same experience with carbon and dirty glass. I like the effects that it leaves too, in both my hot glass and my slumping. I'm still looking to remove the carbon prior to working the glass if possible. I've never had it burn off or disapate.