Dealing with Many Bubbles--after the fact

[Arti]

Any idea of how to save these pieces? Two large pieces, both fired at the same time, and both had the same result--fifty or so triangular and irregular, bubbles 1/4 to 1/2" spread throughout the surface. between the layers.
Here are the factors: both were already two layers fused fairly flat, both about 14" square. As usual, I added a top layer for a second fusing. But I'm using a different kiln and haven't got the bugs out. There MAY have been a tiny bit of moisture left on the top layers. Also, there MAY have been a small leak in one side of the kiln (large 30x60" interior, top elements). Firing schedule was 65 degrees to 1250 over 3hr15min, soak 15min, 30 min to 1410, soak ten, 10 min to 960, soak 1 hr, 2hr45min to 700 and off. (I'm not able to open kiln during firing)
But the real question is, what can I do now???? Can I save these pieces? I know what to do next time, but what can I do this time? These are table-tops, and must be flat. Thanks, y'all, Carolyn

[Cynthia]

...Firing schedule was 65 degrees to 1250 over 3hr15min, soak 15min, 30 min to 1410, soak ten, 10 min to 960, soak 1 hr, 2hr45min to 700 and off. (I'm not able to open kiln during firing)
But the real question is, what can I do now???? Can I save these pieces? I know what to do next time, but what can I do this time? These are table-tops, and must be flat. Thanks, y'all, Carolyn

I think you are saying that you ramped up at 400 dph to 1250?. At any rate, there are a couple of things to do to decrease the trapping of air between glass layers.

Put smooth sides of glass together. Single rolled has a rough side and a smooth side. If you have an option, put the smoothest sides together.

Use a bubble squeezing schedule. From 1100F to 1200F on the way up, I slow down my ramp rate to 60 or 100 dph then ramp at 500 dph to full processing temps.

In this range (1100 t0 1200) the glass is softening but not laminating, so it can squeeze out the trapped air as it softens and moves. This is a schedule that Lynn Chappell posted a long time ago. I tried it and it has always worked well. Hopefull this will prevent future bubbing for you.

Can these pieces be saved? Once the air is trapped, it's trapped. Some fusers have been able to decrease the appearance by refiring, but I don't know how it's done. Someone is sure to give you some tips.

[charlie]

[quote="CynthiaCan these pieces be saved? Once the air is trapped, it's trapped. Some fusers have been able to decrease the appearance by refiring, but I don't know how it's done. Someone is sure to give you some tips.[/quote]

drilling to open the bubble, thenfilling with frit. you'll still see them though, as patterns or marks rather than bubbles.

[Lisa Allen]

I agree with Cynthia that the bubble squeeze is the way to go for future pieces. I usually slow down to 50dph between 1100 and 1250.

On pieces that already have trapped bubbles, I have drilled them out from the bottom and refired (with bubble squeeze included in schedule) with success, however, these were opaque pieces with a clear base that just had a rashy look on the top. I am assuming that if you can see the bubbles, your pieces are transparent. Drilling leaves scars that will be visible through transparent, but didn't matter so much on my opaque topped ones.

Lisa