Hi all! In fusing three layers of glass to make a cab yesterday, the top piece of clear backed dichroic retained some of it's shape and seemed to sink partially into the rest of the bead, but part of it remained sticking up (picture a sinking ship!) I'm using Bullseye 90 glass and fired at 1550 for 10 minutes. Everything else in the kiln flat fused, as well as the first two layers of the piece. Any ideas on what might have happened? I bought the dichroic scrap from a reputable person, but wonder, if it was a different COE, would this cause the problem?
Thanks! Larissa
fired a cab, top layer of glass did not flat fuse
Moderators: Brad Walker, Tony Smith
sometimes dichro doesnt fuse flat, and the edge will stick up, or a corner will stick up. it's very annoying when that happens. in particular, i've noticed this with fibroid, which has a parallel combed texture. you could maybe grind off that area and refire the cab -- maybe a little hotter -- and teach it a lesson.
PS -- i dont believe i like that 10 minute firing. too fast for my taste. you probably have a smaller hot box kiln, different than what i have, but i fire a 8" sq. shelf of cabs this way: 0-500F over about 20 or 30 minutes, and then AFAP to 1500, or a bit more (i look), and that takes about 45 minutes.
i dont think the coatings settle down into a fused cab when they're fired on the Express Train to Glory schedule.
PS -- i dont believe i like that 10 minute firing. too fast for my taste. you probably have a smaller hot box kiln, different than what i have, but i fire a 8" sq. shelf of cabs this way: 0-500F over about 20 or 30 minutes, and then AFAP to 1500, or a bit more (i look), and that takes about 45 minutes.
i dont think the coatings settle down into a fused cab when they're fired on the Express Train to Glory schedule.
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Paul Tarlow
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The fact that your cab is in one piece indicates that the dichoic you used was 90 coe. If you fuse an item using glasses with different coe you get cracking or outright breaking of the fused item, not incomplete fusing. If it would work for your design you might try making the dichroic layer the middle layer of glass in the layup. Another tip when using dichroic is to make the top layer about 1/8" larger than the dichro to allow it to drape over and enclose the dichro so none of the coating is exposed on the edge of the cab.
Your information about your firing schedule, " I'm using Bullseye 90 glass and fired at 1550 for 10 minutes." leaves us wondering if you held the cab at 1550 for 10 minutes after a more gradual firing schedule or if you reached 1550 in only 10 minutes. A more complete firing schedule including information about the size, model or type of kiln you are using plus temperature change rates and holds of your firing segments would allow readers to understand how your item was fired and be able to offer suggestions for firing which might help you.
Best wishes,
Tom in Texas
Your information about your firing schedule, " I'm using Bullseye 90 glass and fired at 1550 for 10 minutes." leaves us wondering if you held the cab at 1550 for 10 minutes after a more gradual firing schedule or if you reached 1550 in only 10 minutes. A more complete firing schedule including information about the size, model or type of kiln you are using plus temperature change rates and holds of your firing segments would allow readers to understand how your item was fired and be able to offer suggestions for firing which might help you.
Best wishes,
Tom in Texas
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Duane Sitton
- Posts: 7
- Joined: Sun May 11, 2003 6:30 am
- Location: Independence, KS
Tony wrote:
"If it would work for your design you might try making the dichroic layer the middle layer of glass in the layup. Another tip when using dichroic is to make the top layer about 1/8" larger than the dichro to allow it to drape over and enclose the dichro so none of the coating is exposed on the edge of the cab."
The idea from Tony has solved the same problem for me. -Dichro down on small pieces not fusing well to the lower layers.- Sometimes though I would rather not add more glass. I have wondered, but not tryed, grinding back the dichro from the edge. I think it might cause it to behave. Does any one know if this would help?
Duane
Who has very little experience but lots of desire.
"If it would work for your design you might try making the dichroic layer the middle layer of glass in the layup. Another tip when using dichroic is to make the top layer about 1/8" larger than the dichro to allow it to drape over and enclose the dichro so none of the coating is exposed on the edge of the cab."
The idea from Tony has solved the same problem for me. -Dichro down on small pieces not fusing well to the lower layers.- Sometimes though I would rather not add more glass. I have wondered, but not tryed, grinding back the dichro from the edge. I think it might cause it to behave. Does any one know if this would help?
Duane
Who has very little experience but lots of desire.
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Duane Sitton
- Posts: 7
- Joined: Sun May 11, 2003 6:30 am
- Location: Independence, KS
Previous post should have quoted Tom not Tony. Sorry Tom.Not quite the express train to glory schedule :-)
Thanks everyone for the great information. I think I figured out the problem from your replies, the dichroic piece was upside down. I knew it was upside down (I tack fused the piece first for fun and liked the effect), but didn't know the consequences when flat fused. Sorry I didn't provide all the basics about the firing schedule, I'm learning! I have a Sierra kiln, 8X8 in. shelf and I ramp up at about 1400 degrees per hour, then soak for 10 minutes at 1550, then let it cool on it's own. It takes a bit to get up to temp - much more than 10 minutes! 
Thanks again, wonderful board!
Larissa
Thanks again, wonderful board!
Larissa
reconsidering...
It's very late and perhaps I'm not thinking straight, but after I pressed "post" I realize that firing with dicrho down wouldn't necessarily be the problem...would it? The piece of dichro was also textured with ridges and those were facing down as well. Hmmm...
Larissa
Larissa
sounds like you are having the problem that i occasionally have with ripple textured dichro, fired coated side down. most of the time it does not happen; once in awhile it does. i have discontinued using the fine-combed coated glass on earrings because of this problem. i never could figure out why it happened. out of 100 pairs, a few would always be punk. i think you will NOT have this problem with any smooth dichro fired coated side down -- or up, for that matter. in my experience, this problem is related to textured glass.
PS -- having read my post, i should say that the edges turning up with textured glass dichro can happen with the glass fired up or down. it's a fluke problem, happens a small amount of the time, and occurs in either situation. if you were to fire a bunch more cabs, most of them would be OK.
PS -- having read my post, i should say that the edges turning up with textured glass dichro can happen with the glass fired up or down. it's a fluke problem, happens a small amount of the time, and occurs in either situation. if you were to fire a bunch more cabs, most of them would be OK.
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Pama Designs
When you fire dichroic film down onto a piece of regular glass, and if it's hot enough, the middle of the dichro will melt into the glass and the edges of the dichro will form a rim of the dichro metals. (See the piece on my home page.)
When you fire the dichroic film down onto another piece of dichroic film facing up, you will get a curl. This is a nice effect if it's a small square of dichro on top of a larger one. It will curl around all the edges and you'll get a nice little dew drop (see round silver piece called "Doll"). I once had edges of a longer piece create a boat effect, but I believe it was only because the dichro film was touching other dichro film in this way. I refired it a few times with some glass tucked under the part sticking up, but it still wouldn't go down. I finally ground it and refired it.
When you fire the dichroic film down onto another piece of dichroic film facing up, you will get a curl. This is a nice effect if it's a small square of dichro on top of a larger one. It will curl around all the edges and you'll get a nice little dew drop (see round silver piece called "Doll"). I once had edges of a longer piece create a boat effect, but I believe it was only because the dichro film was touching other dichro film in this way. I refired it a few times with some glass tucked under the part sticking up, but it still wouldn't go down. I finally ground it and refired it.
But because the dicho coating itself does not melt, a dicho-to-dichro layering will not always stick. It may look like it's fused, but the smallest effort will break the pieces apart.Pama Designs wrote:When you fire dichroic film down onto a piece of regular glass, and if it's hot enough, the middle of the dichro will melt into the glass and the edges of the dichro will form a rim of the dichro metals.
I find some colours fuse flat (even tiny sizes) - others 'ball up' and need a clear cap to cover the whole piece. Only trial and error will show what will happen.
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Pama Designs