turquoise opal 96 question

[BobbieMatus]

I recently fired a piece of turquoise opal 96 with clear 96 on top and there was a metal looking blob plus a bubble after the firing. Has this happened to anyone? firing schedule
400 to 1220 hold 20 min
400 to 1450 hold 10 min
full to 950 hold 30 min

[Morganica]

How did you assemble the glass? Did you use any kind of adhesive or stickum between the clear and the turquoise? It looks as though you've got some contamination there.

[DonMcClennen]

I doubt that it's the fault of the glass...Maybe something from inside your kiln.

[AndyT]

Looks like the cat's fault.

[BobbieMatus]

glue was used only on legs and tail not on body of cat

[Morganica]

Well, there's some kind of contamination in there--it's pretty classic-looking. Could there have been a pricetag/sticker or something (or sticker residue) on the glass? Paint? Is there a second bubble under the turquoise glass or only the visible bubble between the turquoise and clear?

I have a hard time believing it's the glass--whatever the contamination is, it outgassed to make the bubble, and it's a nice, round shape, just like a sticker or a dab of glue/paint/metallic marker/etc. That argues that there was something fairly significant added to the glass at that spot, after it was annealed by the manufacturer but before it was fired in your kiln.

[BobbieMatus]

there is only the bubble between the clear and the turquoise. there was nothing on the glass, no label

[Valerie Adams]

That charcoal spot looks exactly the same as the one time I used white glue between my glass.

[rosanna gusler]

yep looks like carbon from glue to me. rosanna

[BobbieMatus]

didn't use any glue on body of cat. I use super glue and used it only on the legs. I emailed spectrum and their first response was glue. Spectrum has asked me to mail them a piece of the glass.

[Judd]

If the glass was clean and without blemish, I don't think that is what caused the bubble. I see lumps around the legs. So you layered the glass around the cat's booty, right? If there was a gap there and you used too much glue, it's possible when the glue burned off the sooty gas migrated to the gap, formed a bubble, then cooled. Just a thought.

[BobbieMatus]

sounds like the most possibilty