sharp edges and small crack with a few bubbles

[buddys46]

so I hope this isn't too long a post. I fused a 10x10 piece first layer clear with black on either side and design in the middle. First fuse fine. Second fire was a clear sheet and dediced to do a bubble squeeze from Spectrum website. schedule
1st seg. 250 -250 hold30, 2nd 250-250 hold40, 3rd 200-1250 hold 20 4th 250-1370 hold 20 ,5th 300-1465 hold 10, 6 9999-950, 7th,200-800 hold 10 and 8 300-100 no hold

had to fire on fibre paper as my shelf as it would not fit on my shelf. So I had bubbles which I can live with. A small hairline crack on right side in the black and sharp edges which can be from the fibre paper????
My question is I want to now slump this but am afraid of doing anymore damage ie cracks..Can someone kindly suggest a schedule or any help . I haven't been playing for a few years and have forgotten a lot obviously..Thanks so much
I seem to be having issues attaching my pic as well..not my night

[Judd]

1) You should have had an anneal hold at 950.
2) You're sure this is all compatible glass, right...? You used only glass certified as being compatible?

Just being sure. Many people have told me they have mixed 90 with 96 because they thought it was compatible, which it's not.

[Brad Walker]

I fused a 10x10 piece first layer clear with black on either side and design in the middle. First fuse fine. Second fire was a clear sheet and dediced to do a bubble squeeze from Spectrum website.

Can't figure out what you're saying. You fired two times? One with what? And then you added what?

schedule
1st seg. 250 -250 hold30, 2nd 250-250 hold40, 3rd 200-1250 hold 20 4th 250-1370 hold 20 ,5th 300-1465 hold 10, 6 9999-950, 7th,200-800 hold 10 and 8 300-100 no hold

You've entered something wrong here. That schedule doesn't make sense. Was this the first firing or the second?

had to fire on fibre paper as my shelf as it would not fit on my shelf. So I had bubbles which I can live with.

Not sure what this is either. What kind of bubbles? Was the piece larger than your shelf and you had the paper extend over the edges?

A small hairline crack on right side in the black and sharp edges which can be from the fibre paper????

Maybe, maybe not. Need more info.

My question is I want to now slump this but am afraid of doing anymore damage ie cracks.

Never slump until the piece is the way you want it. If it has cracks, sharp edges, bubbles, etc, you need to fix them before you slump. If you don't fix it before slumping, your options to repair are greatly diminished. And you'll just go from a flat piece you're not happy with to a slumped piece you're not happy with.

I seem to be having issues attaching my pic as well..not my night

The photo must be a jpg and smaller than 400K. If you want, you can email me the photo and I'll post it for you. My email is wg AT warmglass.com

[Judd]

Oh. No. You have to re-fuse it to remove the crack, unless the crack is due to non-compatibility. If it's not compatible glass, your project is toast.

[buddys46]

Hi Judd
I have sent you an email with a better explanation, I hope

[David Jenkins]

Pictures?

[Brad Walker]

From buddys46:

So first fire was 1sheet of clear two pieces of black on either side and the small design in the middle. The second fire was just a clear glass ontop. You cant see in the pic but on the right hand side in the black there is a hair line crack that runs 3/4 of the wsy up. That firing schedule was the bubble squeeze from spectrums website. All glass is spectrum 96 so allis compatible I have a skutt hotstart and did not want to use the preset schedule as it never seems to get hot enough to full fuse on thicker pieces on second firing so this is why I chose the other schedule. Which I did with some hesitation.So what kind of refire schedule can I use to fix this. Thanks again so much

[Valerie Adams]

This is a simple design that could've easily been accomplished in a single firing. Assuming your glass is compatible, create the base with the black and clear, then cap it with the clear. The green design element should not be sandwiched between the layers of glass (that encourages bubbles; it's referred to as a bubble sandwich). Place the colored design pieces on top, and fire.

In my kilns, with Bullseye glass, my schedule would look like this:
300° to 1150°, no hold
50° to 1250°, hold 30 minutes
600° to 1430°, hold 15 minutes (this ramp would be slower with a larger piece, and the hold depends too; I visually confirm that I've got the result I want)
anneal as required for the piece

[buddys46]

Glass is compatible, i used system 96 in a hotstart kiln only 13" wide..So my question is now..how do i fix this..ie firing schedule to remove sharp edges as i still want to slump it.

[Stephen Richard]

For some reason you do not have a soak at the annealing temperature. This soak is important to equalise the temperature throughout the glass before going on to the annealing cool.

If your sharp edges are needle points, you need to use some means of grinding them off. You need to work down in grit size to about 600 to get a bright edge in the slump. If you want to fix by refiring, dust kiln was powder over the fibre paper. You can smooth it with a plasterer's float if you want.