- This topic has 8 replies, 5 voices, and was last updated 12 years, 3 months ago by Anonymous.
- April 7, 2009 at 4:48 pm #9077
When fusing two pieces of glass 12″ in diameter, I get one or two giant bubbles. This happens every time, but does not happen with smaller pieces. How do I adjust my firing schedule to let the air/gasses out before the edges seal?April 7, 2009 at 6:42 pm #11246steve worcesterParticipant
What is your current schedule and what type and shape of glass?
Steve WorcesterApril 7, 2009 at 9:26 pm #11247
The shape is round. I’m trying to make a bowl. I’ve tried a 4-segment and an 8-segment firing schedule. The full fuse 4-seg. pgm is as follows:
300degrees/hr 1250 degrees 20 min.
600 1450 10
9999 960 60
100 700 1
I’ve tried different kinds of glass, both 96 COE and 90 COE. Firing with the 4 seg. pgm. I got two giant bubbles; with the 8-seg. I got only one. I’ve gotten the bubbles every time using large (12″) pieces, but never with smaller pieces.April 7, 2009 at 11:26 pm #11248Mark HughesParticipant
I would use a bubble squeeze by slowing down to 50 deg/hr between 1250 and 1450, this should eliminate your bubbles.April 8, 2009 at 3:47 pm #11249
Thank you. I’ll try this and see what happens.April 8, 2009 at 5:43 pm #11250bookie13Participant
You may want to take this reply with a grain of salt since I only work small, but I always put my bubble squeeze (50 dph)between 1100 and 1250. After 1250, the bubbles are already captured in place.
Barry KaiserApril 9, 2009 at 1:24 am #11251
That’s a good point and worth a try. I’d better get busy and see what works. Thank you for taking the time to respond to my Giant Bubble problem.April 12, 2009 at 6:02 pm #11252
With the help of forum members, I was able to conquer my Giant Bubble problem. I inserted a bubble squeeze at 100 degrees with a 20 min. hold. Perfect.April 12, 2009 at 6:23 pm #11253AnonymousInactive
Be careful going slowly between about 1325° F and 1425° F, With most fusible glass devitrification flourishes in this range. A bubbles squeeze can generally be accomplished below 1300° F without the risk of glass scum. In fact, I have recently lowered my squeeze/soak temp to 1225° F with excellent results.
Helios Kiln Glass Studio
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