I have two pieces of clear 96 COE glass – with overlays of color glass. One is full fused and I have now cold worked the edges. Question – do I fire polish first and then slump? Or will fire polish occur in the slumping process?
The second piece is clear 96 COE glass with overlays of color that has been slumped into a shallow bowl. I have had to cold work the edges in a few places because of some glass hazing. Will putting this piece thru the slumping process again fire polish the edges? Should I coat the cold worked edges with anything before putting in kiln?
Slumping temps are lower than traditional fire polishing temps. However, depending upon to what degree (as in how smooth, not how hot ) you coldworked, the edges may look fine with just a slump.
I have found that starting with a 120 grit diamond pad (on a lap), moving to 400, and then slumping, provides a nice edge. I slump at fairly low temps — no higher than 1220 in my particular kilns (and quite often I skip to anneal before that). Obviously, that depends upon the size/shape you are slumping.