fire polishing

[bskirwin]

this is going to be a simple, beginners question..... When I a slumping a single layer of glass onto a mold, do I first fire polish the sides in a separate firing ( and to what temp?) and then slump???? I have been grinding the sides with my little diamond grinder, but it chips the glass too much.... Looking for a better solution. thanks.

[Barbara Muth]

Try the diamond pads sold by Bullseye. They are great for cleaning edges, and you can get the edges pretty polished without a firepolish. I tend to shoot up to 1300 when the slump is done for just a minute to firepolish and then anneal. That tends to work for me.

[Phil Hoppes]

You can firepolish and slump at the same time in most if not all cases. The temp for firepolishing starts around 1200 and goes up to 1300. It will vary depending upon the size of the piece, the depth of the slump and the type of finish you are looking for. Most of my work is rather thick (3/8" - 1/2") and my glass is always smaller than my mold. This is important as in running to a firepolish temp, if your glass is larger than your mold, the higher firepolish temps will cause your piece to wrap around the mold. This typically shouldn't be too much of a problem if your glass is 1/4" or less in the extent it is larger than the mold. Much more than this and you can have your glass lock on to your mold, in which case you will need to break your mold to release your glass. Not a good thing. Back on the temps, make your rise at a temperature that works with the thickness of your glass. If you are doing a single layer design you can run up at 400dph, a 2 or 3 layer you probably want something closer to 200dph. Run it up to your firepolish temp and hold for a short time, say 3 min and then run your anneal cycle. The hold probably is not necessary. I do it but I'm guessing it is not required. The polish temps in the 1200 to 1250 range will give you a matte type of finish. This looks quite distinctive and can work well with a number of designs. The 1250 to 1300 range will give you a high gloss finish. I run 200dph to 1300. This gives both a well defined slump (lots of detail from the mold) and very high gloss finish.

Cheers,

Phil

[bskirwin]

thanks so much for the input, I will try them out.... barabara