Firing 90 Coe Bullseye with 90 Coe Wissmach
Posted: Fri Jun 29, 2012 11:18 pm
I'm sorry I don't have photos, I'll try to give the best description I can. I cut two circles, one a blue 13 in (bullseye) and one a 14 inch black circle (wissmach ) . I put 4 dots of glue and centered the blue in the center of the black. So I would have a black rim on the blue. I decided to flip fire for crisp lines. The blue (smaller) on the bottom with the black (larger) on top. I'm using a skutt clam shell kiln
My schedule :
300dph to 1150 hold 45 min
50dph to 1240 hold 45 minutes
100dph to 1370 hold 20 min
400 dph to 1460 hold 10 min
AFAP to 950 hold 60 min
150dph to 800 hold 10 min
250dph to 650 no hold
When I opened the kiln there was a huge 3 inch wide by 2 inch high looking volcano (popped bubble) that sent black flakes all over other things in the kiln. Looking into the popped bubble there was black glass on the bottom . It looked like the black wissmach separated and popped. The bottom (blue) had such a beautiful finish .. No evidence of the disaster on the black side.
It also had unpopped smaller bubbles all around the rim. Undoubtably the ugliest glass I've ever made. well, except for that weasel I was commissioned to make in stained glass.
Did I trap air by putting a larger piece on top? I've done this so many times to make smaller bowls with a rim the same color of the underside.
Could the black wissmach have separated ? The bottom of the 2in high pop was black..not blue like the bottom.
I'm embarrassed to admit but I tried to fix it ( it was going to be a gift after I painted the blue side with a black design) I sandblasted both sides and the black side (with the volcano) I broke off the popped bubble and brought it back flat ... I flipped it and Refired it (same schedule) and this time the blue (smaller circle) was on the top and it had 2 very obvious lumps on it. This is the largest bowl I've attempted to make ..where did I mess up? If I flip it over (yet again) maybe, just maybe could it fixit? Or should I start over?
Any help would be greatly appreciated
Thank you, kindly
S.T
My schedule :
300dph to 1150 hold 45 min
50dph to 1240 hold 45 minutes
100dph to 1370 hold 20 min
400 dph to 1460 hold 10 min
AFAP to 950 hold 60 min
150dph to 800 hold 10 min
250dph to 650 no hold
When I opened the kiln there was a huge 3 inch wide by 2 inch high looking volcano (popped bubble) that sent black flakes all over other things in the kiln. Looking into the popped bubble there was black glass on the bottom . It looked like the black wissmach separated and popped. The bottom (blue) had such a beautiful finish .. No evidence of the disaster on the black side.
It also had unpopped smaller bubbles all around the rim. Undoubtably the ugliest glass I've ever made. well, except for that weasel I was commissioned to make in stained glass.
Did I trap air by putting a larger piece on top? I've done this so many times to make smaller bowls with a rim the same color of the underside.
Could the black wissmach have separated ? The bottom of the 2in high pop was black..not blue like the bottom.
I'm embarrassed to admit but I tried to fix it ( it was going to be a gift after I painted the blue side with a black design) I sandblasted both sides and the black side (with the volcano) I broke off the popped bubble and brought it back flat ... I flipped it and Refired it (same schedule) and this time the blue (smaller circle) was on the top and it had 2 very obvious lumps on it. This is the largest bowl I've attempted to make ..where did I mess up? If I flip it over (yet again) maybe, just maybe could it fixit? Or should I start over?
Any help would be greatly appreciated
Thank you, kindly
S.T