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@kelihiett I too ned help with large crater bubbles easyst

I fused a 96 COE dichroic 3 x 3 square onto System 96 black 5 x 5 using the System 96 firing schedule (which I swear by) - but this time, I got big and small bubbles. Haven't had this problem since I started using this schedule and the glass is too expensive to have this keep happening - twice now. I noticed that Roy Kapp has a photo of one he did with a double plate mold (Item# 7448) and wonder if he would share his fusing schedule with me. I have ordered this plate mold and would like to try again. Thanks! Sally

Try soaking the mold in warm water for a few hours. Then use a brush with nylon bristles to clean the wash off. We recommend using Primo Primer on casting molds. Apply with a 1/2" soft bristle brush to help maintain the details of the mold. Four thin coats is standard. Coat with at least one coat before each new firing.

I am having a problem removing old kiln wash from a mold with small ovals on it. I used my regular kiln wash (Bullseye shelf primer) - should I have used something diferrent for a small details mold? Or, should I put a fresh coat of kiln wash on after each firing, (hopefully, never having to remove it). Can anyone suggest how to do this without wrecking the mold? (It would also be difficult to clean my pot molds - how does everyone else do theirs?) Thanks for your help. K

@jwhitehead I don't know if you ever got an answer to this. You did get a bubble that popped. You can prevent this by firing on 1/8" thick shelf paper. This will allow the trapped air to vent out through the paper fibers instead of through your glass.

I used the Safari browser on a Vista machine and right clicked, "download linked file" and had no trouble at all. It automatically downloads to the download folder, then you just have to click it to open it. Hope that helps.

@preciouspeacock. Devitrification can occur when the glass has been heated too long as well as from high temperature. Therefore you might experiment with the length of time you are annealing. We find that two hours is sufficient and anything over that is not necessary. We generally will hold a 12"x12" - 1/4" thick piece for 60 minutes. As the size and thickness increases so does the anneal time with two hours being the top.

@jhaan Thanks for this .I have always thought glass had to be cooled very quickly through the devitrification zone to avoid greyness hence the flash cool.I must have misunderstood or read some conflicting information. I will check out the system96 website

The first thing I noticed is the use of flash cooling. This rapid drop in temperature will cause stress to the glass. The glass should be allowed to cool slowly reaching the annealing temperature. Some glass manufactures recommend stepping the cooling temp down again after the initial anneal as well. The System 96 website has a Firing Guide showing this process and can be used with both COE's. Larger pieces do require more control when firing so keep a good record of what works and what doesn't for future reference .

April 18, 2011 This is not a comment it is a question or rather a plea for help.I make fused glass pictures in the uk.Recently I have two 12" squares which have cracked across one corner one after more than a year of moving from gallery to gallery. Before fusing I soak at 555c for 1 hour then soak again at 671c for 30 mins then fuse at 780 around 10 mins then flash cool.Finally I soak at 516c for 3 hours or four and then turn off the kiln and cool usually overnight. My kiln is a top loader paragon pearl 18 clamshell firebrick. larger pieces are drilled at the edges and screwed to board. Do I need to slow down my cooling process?or is my approach all wrong for this type of work.I have had no trouble as yet with panels which are smaller 6 or 8 by 12" and layered 2 thick. I was a jeweller for 20 years and discovered dichroic and fused glass about five years ago.I made glass jewellery first which worked very well.Then clocks and finally panels adjusting my annealing each time. These works are usually no more than 8 mill thick in any place though there are different depths in them and sometimes bullseye and wasser together. Any ideas and help would be most appreciated Yours Deborah A very confused by all the annealing info I have read recently uk glass maker