To pop or not? -

To pop or not?

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To pop or not?

Postby frizzygirl » Tue Oct 06, 2015 4:13 am

Hi all

I've made two plate blanks and have ended up with bubbles in both, the smaller being the worst. I think I made a basic mistake of not drying the glass properly after cleaning them as I followed the bullseye schedule for plates under 50cm, to the number and have not had this issue before.
I have been through the forums search and it seems I have two options, to drill small holes in the bubbles and to refire, or to try turning them over and refiring them but am worried any bubbles that come to the top will distort the patterns.
Looking at the size of the bubbles, what would be the best option please. Also if I drill holes do I fire it pattern down again or up.
The plate sizes are 200mm and 180mm respectively.
Thank you in advance.

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Re: To pop or not?

Postby DonMcClennen » Tue Oct 06, 2015 11:26 am

In the future I would suggest you use a schedule that includes a bubble squeeze and add chads between layers! This will 100% eliminate your trapped air!
"The Glassman"

Brad Walker
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Re: To pop or not?

Postby Brad Walker » Tue Oct 06, 2015 11:52 am

I would flip and refire, not pop. Too many bubbles to pop and flipping will smooth them out.

The chad method Don mentions will help prevent the bubbles in the first place. Chads are small beads of glass placed at the outside edges between the two layers of glass to help air escape. a bubble squeeze is also helpful, but by itself won't always do the job.

Valerie Adams
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Re: To pop or not?

Postby Valerie Adams » Tue Oct 06, 2015 1:07 pm

I must be missing something here. Are the white bubbled pieces the backs of the other photo? If so, I'd just slump them, learn, and move on.

Drying your glass has nothing to do with the bubbles you've got. As was pointed out, you need a good bubble squeeze in your schedule. Unlike the other two posts, I never use chads. I've tried them in the past and always see them. I'd rather tweak my firing schedules.

The Hobbyist
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Re: To pop or not?

Postby The Hobbyist » Tue Oct 06, 2015 5:58 pm

I have a slightly different take on the problem.

It appears the pieces were fired with stringers on the bottom and a couple layers of glass on top. The interface between the stringers and the bottom layer is what trapped air and formed the bubbles which rose to the top. I don't believe a bubble squeeze nor chads will eliminate that problem.

I would suggest firing the pieces with the stringers on top. If you take it high & long enough it will flatten out. The down side is that they will probably not give you the crisp lines you have now since the stringers will tend to spread whereas they couldn't before when they were on the bottom.

I think it was Bob Leatherbarrow (or maybe Ron Coleman) that used to get around bubbles by watching the fuse closely and stopping it when they were just emerging. You might try that on these pieces with a flip-n-fire.

Jim "The Hobbyist"
"With or without religion, good people can behave well and bad people can do evil; but for good people to do evil—that takes religion. " Steven Weinberg

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Re: To pop or not?

Postby frizzygirl » Wed Oct 07, 2015 4:22 am

Thanks for your comments and advice.

The bubble squeeze was 30 mins at 1250F and I have never had a problem before which was why I was so confused and posted the question.

I think Jim is right about the stringers causing the problem as after reading his post I checked the bubbles on the back in relation to the stringers on the top. They are definitely in the spaces between the stringers. The smaller plate has more design and more bubbles so it makes sense.

Thanks Jim, I will learn from this as I thought having the stringers on the bottom would be crisper but would also let the air escape due to the design being raised.

Thanks again all.

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