Warm friends,
I recently completed an item that has a total of a number of layers of glass, it isa 6 x 6 " tile. The piece developed a small interior crack which I would like to try and fix.....can I just bring the item slowly back up to 1450 and fuse again? (I think I caused the crack as I looked at piece before it was completly cool forgetting the temp. of the kiln is not necesarily the temp of the item, yes I will learn!).
Also I slumped the piece using the attached mold and frankly like it better as a flat tile. By using this mold as you can see the corner tip up slightly, by refiring to correct the crack will the piece slump back into a flat piece OK?? Your input is most appreciated, Lydia of Ohio
Lydia,
You can slump that back flat. It might has shrunk some but probally not. Question... is what you are calling a crack really a crack or an air bubble? Going to full fuse temp will not get rid of it, if it is an air bubble.
If it is a crack, which I doubt that looking in a kiln for a moment would cause, you will not need to go to the same temp. Glass gets softer which each furing.
Stuart Clayman wrote:Lydia,
You can slump that back flat. It might has shrunk some but probally not. Question... is what you are calling a crack really a crack or an air bubble? Going to full fuse temp will not get rid of it, if it is an air bubble.
If it is a crack, which I doubt that looking in a kiln for a moment would cause, you will not need to go to the same temp. Glass gets softer which each furing.
Good luck,
Stuart
Stuart, I don't think I have ever heard or read that glass gets softer with each firing. Can you explain it to me?
Lydia, I recommend heating the glass up verrry slowly. Soak it for half an hour around 1050 or 1100 and it should be flat.
I would agree with Stuart that it probably isn't a crack if it is inside the glass and you can't feel it on either side. It probably is trapped air. Depending on the glass you used, sometimes you can get a line of trapped air that could look like a crack. If you take the glass back up to full fuse and soak it long enough, the air will rise to the surface, but what will then happen is that the glass below the bubble will rise up with the air to fill the space and you will have a line of the bottom color glass on your surface. Sometimes to get rid of a bubble I will flip the piece over so the bottom is facing up, fire away and the surface that is marred is the bottom surface. But then I have to sandblast the top that is now on the bottom and fire it once more to firepolish. Maybe worth the effort in my big pieces, but I am not sure I would make that effort for a 6x6.
Good luck!
Barbara
Barbara
Check out the glass manufacturer's recommended firing schedules... LATEST GLASS
I am afraid it is a crack as I can feel it with my finger nail on the surface a little. I am afraid I just didn't peek, being the impatient fool I am some times. I pulled it out when the kiln said about 180, but then realized the piece was much hotter. The piece has a total of 7 layers, some only two layers some decorative items on top making it 7 layers. It is the Ohio State University logo, (don't turn me over to the logo police). I am not going to sell it but give to a Buckeye fanatic friend or two. I really like the look, but even if the crack does not extend, don't want to give a gift that has a crack even a small one.
So Stuart if I go say to 1375-1400 I should be able to heal it? I know I will still have a scar, but don't want to be able to feel it.
Thanks to all for your help, Lydia
7 layers.. the problem might not be that you pulled it out, but that it was not annealed enough. You need to go very slow on the ramp up.... and if you question if the speed you want to go is slow enough it is not, go slower. There is a LARGE chance that it will crack on the way up if it was not annealed correctly. Then when you anneal it on the way down... Stop at about 980° for a long time... then very slowly bring it down to about 750°. Then have the kiln turn off and leave the building until the kiln reads room temp at its own speed. (figured it would be much easier for you not to peak if you were not there)
At what temp did you originally fuse it to? Remember this time that you now do not have 7 different layers of glass for air to get around to heat up... you have 1 block that is 7 layers thick.. it will take longer to heat up, so go slower all the way up.
I really hope that you have a kiln with a computer.. it will be very hard to do this without one.
The glass is all spectrum 96, the base is 2 mm, the rest is 3. The reason I think I created the small crack is that yes, when I pulled it out to darn early no crack...then as I realized it was hot and put it down. Later low and behold when I put it upright in the stand you could see a small crack that you can not see when it is laying down. I have done a second one, no cracks...so yes it was me. Stuart like you idea about going away...usually I put my items in the kiln in the evening, that way I can not get to them to the morning when I wake, what a big kid I am.
I originally run up to 1450, yes thank god I have a computer kiln. I got it when when I was doing beads and it is a wonderful item, right up there with my other favorite the garage door opener!
It sounds more like insufficient annealing time. To be safe the annealing needs to be based on the thickest portion of the piece. When you refuse the piece, go as slow as possible as you ramp up. There is likely still stress in the piece that has not been relieved. Don’t be surprised if the crack grows during the refusing.
Stuart Clayman wrote:Lydia,
You can slump that back flat. It might has shrunk some but probally not. Question... is what you are calling a crack really a crack or an air bubble? Going to full fuse temp will not get rid of it, if it is an air bubble.
If it is a crack, which I doubt that looking in a kiln for a moment would cause, you will not need to go to the same temp. Glass gets softer which each furing.
Good luck,
Stuart
Stuart,
Can you explain why you believe that the glass gets softer each time it is fused? I am skeptical of the information.
Well Doctors I am afraid the patient died on the table. (Services no slash that wake to be held in thirty minutes, all tip their pint!).
The good news is that it's brother survived and I am quite pleased. Will try to post photo soon.
Again, my sincerest thanks for all of your help and patience. Lydia of Ohio
