Temps for Iridescents

I'm new to warm glass and am not sure of the temps needed to fuse iridescent glass. Do I need to use higher temps? I thought I read somewhere that I would need higher temps, but with all the reading I've been doing on warm glass, I'm not sure.

firing irid glass


when you work with iridescent glass you do not need to fire higher. Just make sure that you do not fire iridescent glass face down on to another irid glass. They don't like to fuse together at our fusing temperatures. Also when you have the iridescent glass as your base glass and irid side up you will find that decor glass that you place on top of an irid layer will look  more tack fused than full fused. I prefer light colored iridescent glass the irid side towards the kiln shelf - the light reflections are what I'm after. Have fun and keep experimenting.

petra kaiser - www.kaiserlee.com


Irid Glass and Heating/Cooling

The irid surface affects the way the glass heats and cools. 

Any time you have irid in a piece I recommend you use especially conservative firing schedules. 

Helios Kiln Glass Studio


Need more time and temp

 I just took a useful class with Jim Gregory, one of the scientists working to create system 96 glass at Spectrum.  He suggests more time and more temperature is needed, going up to 1520 degrees if you want the irid glass to take on texture.  The full fuse schedule for 1/4" to 3/8" thick glass is 300 to 1150 hold 30, 200 to1370 hold 30, 400 to 1480 hold 10, 9999 to 950 hold 60, 150 to 800 hold 10 and 300 to 80 hold 0. He also mentioned not to use Super Spray on the bottom or it will stick to the kiln shelf and not to fire on fiber paper as it's not compatible.   I hope that's helpful.  Windows listen attentively for the sound of broken glass.

iridescent glass firing

I would love to talk to Jim Gregory - we have had lots of success firing with iridescent glass at regular temperatures using Kaiser Lee Board of course and fiber paper (both are pre-fired products and we never had a problem and perfect detail) - Are you sure he meant fiber paper or may be thin fire paper? Many people are confusing those two. The problem is, those high temperatures can cause sharp edges when you fire single layers of glass.  

petra kaiser - www.kaiserlee.com


Temps for Iredescents

Thank you, Petra, Paul and Jolinda. I'll be fusing the piece today. I'll let you know how it comes out.



 Petra, You're totally


You're totally correct - I AM confusing thin fire paper with fiber paper so it should be fine to fuse on top of fiber paper, I assume (haven't tried it - the prefiring always seems burdensome and thin fire is so smoooooooth. :)
Jim Gregory's email is jimtgee@comcast.net and he was an awesome and friendly guy so I'm sure he would be open to your contact.  He knew a LOT about firing schedules and COE shifting. 

Thanks for your correction,


Windows listen attentively for the sound of broken glass.

Higher temps

Well I just took the piece out of the kiln. I used Mr. Gregory's schedule and it came out beautiful. I fired the piece irid side up with a clear on top. The piece took on an old leather texture under the clear cap. The reflected colors are really great. Thank you all again for your help.

I see the fusing schedule

I see the fusing schedule that was suggested by Jim Gregory, who was working with COE 96 glass.  If I am using Bullseye Glass COE 90, I was wondering if the same schedule can be applied or does an adjustment need to be made?

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