http://http://en.wikipedia.org/wiki/Kimax

I did some search, same glass as pyrex I guess, I will have to do some more searching.

Yes a black film developes where the heat touches the glass, and the film wipes away pretty easily with a paper towerl.
FeedmeWeed Reviewed by FeedmeWeed on . Bowl piece questions I have a glass funnel that I took from my chemistry lab and it fits PERFECTLY into my bong. I cleaned it out real good since it came from a chemistry lab and its been touched by some nasty chemicals. It says KIMAX 58 USA on the side everytime I apply the flame from a lighter to the surface of the glass, a black film begins to cover the glass, and a string odor resembling burnt plastic is emmited. Is this odor coming from some protective coating or something or is this normal for glass, Rating: 5