Tack fuse/air bubble problem

tom suter · Post by **tom suter** » Tue Dec 09, 2003 6:34 pm

I recently tacked fused a piece of Spectrum white 10" x 5" on top of a piece of Red Opal Specturm 12" x 7". I did get a few little bumps(air bubbles). I fired 400dph to 1100 soak 10 min 60dph to 1280 soak 25 min 450 to 1400 no soak. Because this was a tack fuse I could not put a small chad between layers to help the air escape. When I use this schedule to do a full fuse and able to use a chad I have never had a bubble problem. I am not sure what I could do to help the air to escape, most of the bubbles were say at thecenter horizontal but closer to the top vertical edge. The red was previous fired two layers and did not have any bubbles so it was a flat base that the white tack fuse on.

Thanks for any suggestions.

Bob · Post by **Bob** » Tue Dec 09, 2003 7:12 pm

Hi Tom,

That is a tough problem. How about this for a solution... just a guess. Tack fuse at a lower temperature... 1325-1350? if that works for Spectrum. Soak until the edges start to round, or until the bubbles first start to appear as "zits" on the top of the white glass. Cool the kiln to begin annealing.

The idea is to minimize the temperature and therefore the likelihood for the bubbles to grow, and to minimize the growth of the bubbles so they are less apparent.

Hope this helps.

Cheers,

Bob

Tony Serviente · Post by **Tony Serviente** » Wed Dec 10, 2003 1:11 pm

You could put the glass on a washed ss sheet that you've gently bowed, to have a center height of an eigth or so. Put a brass rod under this so the glass doesn't flatten the metal to the shelf. Center the glass on the hump. As it's starting to bend it will do so in a way to push the air out, and if you are tacking the amount of movement and growth introduced by the hump will be minimal. If you need the glass to be dead flat, fire again without the ss sheet.