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Cabochon Making
Posted By: di (142.126.205.68.cfl.res.rr.com)
Date: Saturday, 23 September 2006, at 1:47 p.m.
The "gems" were easy to make. Everyone who fired glass seems to have their own technique for firing, but I will share mine, should you be interested.
As far as making the "gems:"
You place your glass pieces in these molds (which are really "forms" made of ceramic bisque) and fire them in the kiln.
Most folks who fuse glass (using Dichroic Glass) simply layer the pieces on each other and fire the pieces directly on the kiln shelf. However you no control of the size and very little control of the final shape. You know what a control freak I am -- I gotta use the fusing molds! hehehe.
You will need to prep the molds with a kiln wash and fire to 500 degrees prior to using the molds. The kiln wash needs to be applied heavily and smoothly and preferably in one direction.
Delphi sells glass and the kiln wash too.
I used COE 96. You can not mix "COE" numbers, because they have different expansions levels and are not compatible, ie, they will crack where they meet. "COE" is short for "Coefficient of Expansion." The glass should be "fusible" glass, stained glass will not work.I placed coe 96 iridescent square chips in the bottom of the molds (pretty-side-up facing you) and then carefully placed pieces of Dichroic glass on top of the irid. If the glass does not want to stay in place, you can use a TEE-TINY DOT of Elmers glue to keep in place. Then I used COE 96 clear glass noodles and some blue (medium) Frit to finish filling up the area.
The 1" disk had clear glass covering the Dichroic pieces, whereas the smaller 3/4" oval disks did not. The black Frit I used for the 3/4" disks were nothing more than scrapes I had left over from scoring and breaking the Dichroic glass several years back. The stuff is so expensive I couldn't see throwing it away. It's been 7 years, but I finally put it to use. Char, we used Dichroic glass chips when we made the cut-out Christmas ornaments.
The most important thing in filling the mold/form with the glass is to make sure you have a nice high mound of glass extending over the cavity and that all your "mounds" are the same height. I call the mounds -- Mt. Everest.
The photos shown in the link I posted are pieces that came straight from the mold. If you don't fire hot and long enough and do not use the forms, you will have to do some grinding and polishing. No thank you, that sounds too much like house work. hehehe
I use my "four wall" electronic Skutt kiln to fire my work. There are jewelry kilns that have elements in the lid. And then there are tee-tiny jewelry kiln, that are the size or smaller that Hot Boxes.
Fast fire to 1450 degrees (600 degrees/hr)
Soak (hold) the kiln at 1450 for 20 minutes
Carefully open the kiln lid to "flash vent" for 1 minute (until temp drops to 1425).
Soak at 1000 degrees for two hours.
Carefully open the kiln lid and flash vent for 30 seconds.
Soak at 970 degrees for two hours.
Turn off the kiln and allow to cool to room temperature, or 200 degrees or less.Flash Venting prevents the kiln from getting any hotter. Once the glass reaches a certain temperature it will turn cloudy if the heat continues. Electronic Kilns will hold the temperature, and there are two times you don't want that to happen, thus the Flash Venting. Soaking at 1000 degrees is called "squeezing the glass." It help the bubbles trapped inside the glass dissipate.
Soaking at 970 is the annealing stage. Thats what makes all the little pieces become one piece.I have a firing schedule for my other two kilns, but have not used it. I prefer to see the temperature. Yeap, I have a Pyrometer, but its screwed to the wall in the studio, and I didn't want to take it off, besides why should I when I have to electronic kilns sitting right next to the pyrometer.
Talking about my Skutt reminds me that I need to order a digital key board. Mine is getting hard as heck to press. The numbers 4, 5, 6 would barely work last week. I had to push the key pad with my thumb -- really hard, to activate the number. Well, heck gals its 9 years old. I ain't complaining. It's truly been a wonderful kiln.
But like an older car, it has to be serviced from time to time.I fired the cabochons in it!
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