big bubble at base of bowl

[lorimendenhall]

I have a gorgeous bowl with a big bubble in the center from slumping. do I have to fire it flat and re-slump or can I simply attempt to reslump putting it back into the mold as is? I've been told different things so wonder what the sages here think. thanks so much. ps the bowl is 12" diameter, 90COE.

[Brad Walker]

You'll have to fire it flat, then reslump.

More importantly, you'll also need to figure out what caused the bubble in the first place. During a slump, it's usually either holes in the mold that are blocked (or no holes) or firing too high too fast.

[JestersBaubles]

My experience with reslumping without flattening is you'll just get more bubbles

Dana W.

[lorimendenhall]

re-fuse flat first it is. thanks guys. yes, I am working on why I got the bubble. I think I might have ramped too fast even though it was only 300 dph.

[Brad Walker]

I think I might have ramped too fast even though it was only 300 dph.

If you can share your firing schedule, someone may have some suggestions to improve it a bit.

[S.TImmerman]

A couple of months ago I tried my first large bowl and and it had a huge hump after slumping in a bullseye mold- Brad and laurie helped me figure out what the the problem was. NO hole in the center of the mold seemed like the cause.. My first schedule was

large hump

130-800-15
100-1200-30
9999-950-60
100-700-
200-500
300-200

to fix it I drilled a hole in the center and reslumped it (after praying to the kiln gods)
100/800/no hold/
250/1200/0
50 1250/5
9999-950-60
100-700
200-500
300-200

Marked circle for rim

image.jpg (44.32 KiB) Viewed 11094 times

image.jpg (38.73 KiB) Viewed 11094 times

( The color is too yellow in this pic)
I did need to take off about 2 inches as the rim slumped uneven with the higher temp
Thanks again to Brad and Laurie for the help! Im so eager to get these SG orders out so I can concentrate on fusing 100% of my time.

[lorimendenhall]

that's my problem - I forgot to pray to the kiln gods!!!! actually thank you for posting the schedule that worked. it seems very conservative and I plan to try something very similar after I get this bad boy fused flat again.

[Laurie Spray]

I am so happy that this bowl survived after all that work. It is one of my favorites to see!! Yeah!!!

[Valerie Adams]

I look at all those tiny pieces and just marvel that there are people who have that kind of patience! Glad you were able to save it.

[S.TImmerman]

Well, I'm just flattered by you!


I truly am! If it wasn't for Brad Walker and Laurie Sprays help and advice online via messages after that hump..I was dazed and confused! How did it happen! BE's sound mold to boot! A good schedule too!



It was the first complicated bowl I tried and really wasn't that hard. Cut strips and then cut those to diamonds. They did need to be perfect to line up and I did have to toss a bunch that weren't. Finally after 1.6 years of fusing I feel I can help others at times!

Thank you for that!
Happy new year!
Shereen