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what could cause multiple large bubbles in a piece which is simply two pieces of glass on top of each other with no inclusions? I used the slow full fuse program that has been used perfectly many many times. could there have been dirt between the layers to cause the large bubbles? how about too much hair spray gluing the layers together? insight please! I am now afraid to make more pieces because I don't understand how this happened. ps - I know the design is horrible, try to get past the ugliness of the piece and concentrate on the technical side of it - lol!!!!

lorimendenhall wrote:what could cause multiple large bubbles in a piece which is simply two pieces of glass on top of each other with no inclusions? I used the slow full fuse program that has been used perfectly many many times.

Was the length of the firing the same as your previous firings?

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com

yes, it's my friend's kiln and she has used this particular program many times with no problems. it's supposed to be "slow full fuse" I just don't see how the air bubbles could have formed.

Are the bubbles on the bottom of the piece or between the two layers of glass?

Jim

they are not on the bottom. it seems like it was air trapped in between the 2 layers of glass.

I love it: "slow full fuse"!
How slow? To what temperature?
And you probably had stuff trapped from the hair spray. If it was just 2 pieces of glass, why did you need hair spray?
Your friend may have been lucky- did she fire the same stuff you did?

And the piece isn't ugly- it looks festive and playful.

If you're using the pre-programmed schedules that come with the a controller, don't. It's kind of like setting your car for "short drive with a few turns" and expecting it to take you shopping without mishap.* Sooner or later it'll get you into trouble.

The problem is that preprogrammed schedules can't take into account the kind of work you're firing or what it needs. More than likely, as Marty said, you had some outgassing of the hairspray between layers (which more than likely isn't necessary), and that combined with the airspaces already between the sheets. If you leave off the hairspray you probably won't have as many bubbles. If you're very concerned about it, lay your decoration face-down on the kilnshelf, set the two pieces of sheet on top, and fire upside down. Any bubbles will rise up and go to the back of the piece.

And the design isn't horrible.

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*Which isn't going to be available on most cars until 2017, but that's another story