Polishing bottom of slumped platter

[cbrandt]

Is it possible to fire polish the bottom of a platter that is already slumped without losing its shape? I've already tried repeating my regular slumping schedule with it on the mold resulting in a small part now slightly shiny and the rest still matte from previous sandblasting. I can increase the temperature but wonder what if any temperature will work if it's not going to make any difference because it's on the mold.

[Brad Walker]

The only part of glass that will shine during a firing are parts that are exposed to air during the firing. So the bottom of a slumped piece won't shine up during the firing.

There are some products that claim to shine up the bottom at lower temperatures, but most don't really result in a shine, just a changed appearance.

[jim simmons]

The only way that I know of, would be to cold work the bottom working all the way up tp a 1400 grit.
fwiw.
The other Jim