bubbles in 1/8" sheet fusing - WarmGlass.com

bubbles in 1/8" sheet fusing

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jerry keller
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bubbles in 1/8" sheet fusing

Postby jerry keller » Fri Mar 11, 2016 2:12 pm

I fused a piece of 1/8" glass 11"x11" with frit on top to 1560 hold 10. A previous post mentioned to hold with a 50 degree ramp between 1150 and 1250 which I did. But I had a large bubble in the center of the piece. So I put a circle of glass in the center, and tried another piece. Then I got four bubbles, outside the center, toward the four corners. The exercise would be to not have any bubbles in the sheet...I don't like to use fibre paper, so it is fused right onto the kiln shelf.

The ramp was for 82 coe, clear 1/8"sheet


bubble in glass.jpg
bubble in glass.jpg (136.73 KiB) Viewed 7428 times

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Re: bubbles in 1/8" sheet fusing

Postby JestersBaubles » Fri Mar 11, 2016 4:47 pm

How thick of a layer of frit?

I couldn't access the picture, but your problem is likely volume. You're taking a single layer of glass and frying it at 1560. If there is not sufficient frit, when the surface tension of the glass causes it to pool to 1/4" thick, you're going to get holes.

Dana W.

Chris Lowry
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Re: bubbles in 1/8" sheet fusing

Postby Chris Lowry » Sat Mar 12, 2016 12:54 pm

I really don't know that much about fusing but those bubbles look like they are under the clear. Are you using kiln wash? If so do you pre fire the kiln wash?

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Re: bubbles in 1/8" sheet fusing

Postby JanG » Sat Mar 12, 2016 2:09 pm

I agree with Dana not enough glass and too hot a fuse.

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Re: bubbles in 1/8" sheet fusing

Postby Marty » Sun Mar 13, 2016 11:09 am

What kind of glass?

Where did you get the schedule?

linn keller
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Location: south tx

Re: bubbles in 1/8" sheet fusing

Postby linn keller » Sun Mar 13, 2016 3:21 pm

it sounds like you're playing "wack-a-mole" with the bubble(s), not dealing with technique. i think you're dealing with a volume (or lack thereof) issue. i'd suggest reading bullseye glass tech notes #5: volume and bubble control. i know you said you're not using bullseye, but what you need to be thinking is technique and concept, not specific glass. also, if you're using a schedule that runs about 80 degrees over bullseye, then any segment(s) within that process, in this case full fuse would need to be adjusted, and the bubble squeeze that you included (1120-1250) would need to be adjusted accordingly. also, i believe most people use the temp of bubble squeeze to refer to letting air out between layers before the edges seal rather that fusing with a single sheet. if you want to only use single sheet you may have more success with changing ramping speed (to fuse) or not taking it quite so high, just til the frit melts.
linn in deep deep south texas

Bert Weiss
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Re: bubbles in 1/8" sheet fusing

Postby Bert Weiss » Sun Mar 13, 2016 4:38 pm

Fire float glass to a maximum of 1420ºF, and you will never get those bubbles. The glass gets viscous enough to blow bubbles around 1450ºF. Take as long as you need holding at 1420 to get your work done.

Bert Weiss Art Glass*
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