WarmGlass.com

I've been reading about fire polishing, but the fusing classes I attended didn't cover this topic.

The glass will pick up whatever surface is on your mold. Fire polish will only work if the cast glass if relatively flat - because at polish temperatures the glass will start to droop, sag, etc. A lot of people say they hand polish cast glass, but girl that sounds like too much work. Better to embrace a matte surface.

firepolishing is to finish off the top surface, and goes anywhere from a matte surface to shiny. the bottom surface will pick up the texture of whatever it touches (mold, shelf, paper, etc), and you can't get rid of that without mechanical means.

The question is a bit ambiguous, but no, glass does not "need" to be fire polished.

FIre polishing is typically done when the piece is flat, if it has a matte surface that you want to be shiny. If the surface is already shiny, no need to fire polish (or, if you want a matte surface).

I would avoid fire polishing it *in the mold* (if that is what you are asking). This will likely result in over-slumping.

Dana W.

Fire polishing is also used if you've cold worked your edges and want to shine them up to match the surface of your piece.

I would interject here that fire polishing can be done on many items with the use of gas fired torches. Many factories have "glazing" machines that have been used for many years to flame polish a lot of their blown and pressed wares. If you are so inclined you can make ring burners that can fire polish whatever size piece you want provided you make the ring burner large enough. Most stemware that is production blown is put in a machine that scores where they want the rim and then hits it with a very small and precise flame and it cracks off, it's called a crackoff machine and then the rim is fire polished with a ring burner and the piece is rotated in the burner as it is fire polished.
I realize this is more than most of us can use easily or develop, but for larger production it is the way to go. I have even seen a conveyor line that has multiple burners to do the fire polishing and the piece rotates as it goes on the conveyor line.
If you ever get the chance to go thru a large production factory don't hesitate as it is an amazing "trip" to see how industry confronts some of these problems.