How long do I hold at 1200 to ban bubbles? - WarmGlass.com

How long do I hold at 1200 to ban bubbles?

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Nancy
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Joined: Sun Mar 09, 2003 11:10 pm
Location: North Carolina

How long do I hold at 1200 to ban bubbles?

Postby Nancy » Fri Jan 23, 2004 9:38 am

I've been holding for 15 minutes.

How long to get rid of the tiny bubbles?

Thanks.

Jackie Beckman
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Location: Arizona
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Postby Jackie Beckman » Fri Jan 23, 2004 9:55 am

I could be wrong Nancy, but from the way your question is worded it sounds as though you are holding on the way down. Could that be? I think that because you said to "get rid of the tiny bubbles" indicating that they already exist. You need to prevent them rather than get rid of them.

The idea is to hold and go slowly between the 1150 - 1250 range on the way up. Imagine laying down contact paper. You place the center down first and work towards the edge to squeeze the bubbles out. Same with the glass. You want the center to touch first and before the edges seal, you need to "squeeze" the bubbles out.

You can do this by going very slowly through the range mentioned and adding a soak for 20 to 30 minutes, depending on the design, you may even want to add two soaks in there. Another way to let the middle down first is by placing chads (chips, brads, beads, balls) around the edge of the piece allowing the center to drop before the sides, thus squeezing the bubbles out the edges before air gets trapped.

Jackie

Nancy
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Joined: Sun Mar 09, 2003 11:10 pm
Location: North Carolina

Postby Nancy » Fri Jan 23, 2004 11:25 am

Thanks. I don't think I hold long enough.
I was holding on the way up. I'll try going slower.

Paul Tarlow
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Location: Helios Kiln Glass Studio - Austin
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Re: How long do I hold at 1200 to ban bubbles?

Postby Paul Tarlow » Fri Jan 23, 2004 1:45 pm

Nancy wrote:I've been holding for 15 minutes.

How long to get rid of the tiny bubbles?

Thanks.


To squeeze out bubbles I go from 1050F to 1250F @ 75F/hour. I then hold for 60 minutes at 1250F.

That is probably excessive -- but it has been 100% reliable for me.

- Paul

Barbara Muth
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Postby Barbara Muth » Sat Jan 24, 2004 10:20 am

If you are referring to the teeny seed bubbles in a sheet of transparent glass, the squeeze soak won't eliminate those. The squeeze soak prevents the formation of bubbles between your two layers of glass.

Barbara
Barbara
Check out the glass manufacturer's recommended firing schedules...
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