Pits and Flip and Fire - WarmGlass.com

Pits and Flip and Fire

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Drewcilla
Posts: 60
Joined: Fri Apr 11, 2008 9:10 am

Pits and Flip and Fire

Postby Drewcilla » Sun Jul 28, 2013 1:55 pm

My experience is with jewelry. I'm having trouble getting tiny pits in pieces 6" and larger using COE 90. It's been suggested that these are bubbles rising to the surface and bursting. I've been able to repair them with a heavy layer of clear powder but of course I'd like to skip this step. I use a bubble squeeze and go to a top temp of 1465 holding for 10 minutes in my Skutt Firebox. Would going hotter or holding longer eliminate the pits? I've read everything I can find on pits and can't figure it out.

Also, about half the things I have read on flip and fire do NOT mention that one needs to sandblast. The one time I tried it didn't work because the shelf/shelf paper impression was not eliminated in the subsequent firing. Did I do something wrong or is sandblasting always necessary?

Many thanks in advance for your help. I read this board every day and am always learning something new.

Drewcilla

Stephen Richard
Posts: 302
Joined: Sun Jul 06, 2003 4:36 pm
Location: Glasgow, Scotland
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Re: Pits and Flip and Fire

Postby Stephen Richard » Sun Jul 28, 2013 2:56 pm

Surface texture on flip and fire:
I find that a good scrub with a stiff bristled brush is sufficient to clear off any thinfire, shelf wash, or ceramic fibres.
Then a sufficiently high firing is required to alter the surface - for me this is the region of 775ºC for a couple of minutes, done at the rate of about 200/hr. If you do it very fast, you do not get enough heat deep enough into the glass for it to get soft enough to move.

The other question on bubbles has no satisfactory answer from me. I don't find I have too many difficulties with these pin hole bubbles - that is, I don't have them very often. But then I rarely fire faster than 300C from slumping temperature to target temperatures.

Barry Kaiser has a lot of experience with fusing smaller items, and does it very successfully. Perhaps he will have some suggestions.
Steve Richard
You can view my Blog at: http://verrier-glass.blogspot.com/

Drewcilla
Posts: 60
Joined: Fri Apr 11, 2008 9:10 am

Re: Pits and Flip and Fire

Postby Drewcilla » Sun Jul 28, 2013 11:46 pm

Thanks, Richard. I'll give it another try.

Lynn Perry
Posts: 119
Joined: Sun Jun 08, 2003 5:27 pm
Location: East Tennessee

Re: Pits and Flip and Fire

Postby Lynn Perry » Tue Jul 30, 2013 10:22 am

Hi, Drewcilla. I frequently cap dichroic glass with a clear cap. If the dichroic is 1.5mm thick, I use a 1.5mm clear cap and put a 3mm piece of glass underneath the dichroic to minimize dimension changes. By using a 1.5 mm cap rather than a 3mm cap, I have reduced the amount of entrained bubble by half which also reduces the number of pinpoint craters on the surface.
Lynn Perry


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