I may have mentioned this before, ever since Marg popped this in with a package of other less interesting things (paperwork) ;-) - I've been just itching to to try it out. I finally had the opportunity this week.
One very important note regarding the instructions - it mentions to not breath the dust. I think this is understating the importance drastically. This product is very similar to enamel - it's glass dust. DO NOT BREATHE this in. Wear a respirator, and keep a damp towel handy while you work to wipe down any particles that could become airbound as it dries. These are your lungs - take care of them. :-)
The clay is easy to mix. I carefully poured out the full jar into a small bowl, and mixed with the back of a spoon. Initially, I used far too much water, and had to wait for the clay to dry somewhat before I could press it into a mold. It needs to be far drier than you think it does!
The clay only needs to stay in the mold for a moment - pull on the sides of the mold, and pop it out. Smooth out any rough bits with a damp sponge, or use a toothpick in the little nooks and crannies. Allow to completely dry. I left mine for quite a while, but I suspect overnight would do just fine.
Once it's dry, you can sand or carve the glass clay as it will be quite hard. Keep in mind the safety precautions above when sanding!
Here are my first pieces - they could have used a slightly longer final firing time for a bit of extra shine, but I got distracted at the end of the firing session and missed the opportunity.
All in all, it's easy to use. You will of course need a kiln, and I think for the mixed media jewelry artist having one more type of medium to add to your work is worth it. I believe we are planning on bringing this in, but as I was just doing the initial testing - we don't yet have a date. If you are interested in us carrying the Glass Clay - send us a note to let us know!