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I have finished a piece - 1/2" thick, 16" diameter. Bullseye glass. During cold working the piece I scratched it pretty bad so I need to fire polish. I want the piece shiny vs matte and I don't want to cold work it again! It is ready for slump. Suggestions? I'm thinking that I sandblast it then fire:

180 > 1000 > 20 min
300 > 1175 > 30 min
500 > 1275 > 5 min
9999 > 900 > 120 min
100 > 800 > 0 min
180 > room temp and off

What do you think??????

i'm not sure 5 min at 1275 will firepolish. it won't in my kiln. i'd get a light matte surface.

you should look in at 1275, and see if it's shiny enough for you. if not, just increase the time.

Greg,
I wouldn't exceed 150F/h in the initial ramp. Don't see a need for a hold at 1175. Like Charlie, not sure 1275 will do it from a sandblast finish. I'd go to 1300 for up to 10 min. Eyeball to decide. Hold at 900 for 2 1/2 hours and drop to 750 at 90 d/hr. Off at 750. Be sure to dam it as you did in the original firing.

Warren

The hold at 1175 is to complete the slump. I'm trying to avoid damning because that means I have to cold work again. Thanks for the good advice!

Warren Weiss wrote:Greg,
I wouldn't exceed 150F/h in the initial ramp. Don't see a need for a hold at 1175. Like Charlie, not sure 1275 will do it from a sandblast finish. I'd go to 1300 for up to 10 min. Eyeball to decide. Hold at 900 for 2 1/2 hours and drop to 750 at 90 d/hr. Off at 750. Be sure to dam it as you did in the original firing.

Warren

Greg,
The slump will complete before you reach 1300 without a hold at 1175. Didn't realize that you were firing in a slump mold so damming won't be necessary unless you exceed 1300.

Warren