https://youtu.be/7zFDornVRjA
This started out as a fairly thin layer of crushed glass. There was really barely even enough to spread out on the bottom of the crude "mold". The mold was actually just a ring of glass from one of my failed attempts at bottle cutting. Not really a good idea, but it was handy. Unfortunately it melted and fused with the foamed glass, but of course, did not foam itself, but did add to the weight.
I would call this a success. At least it demonstrates that making foamed glass in a microwave kiln is possible.
The resulting "foam" is certainly plenty strong.
I took a kind of shotgun approach as far as what to use as a foaming agent, so I put some of this and some of that.
Due to the rather thin starting layer of crushed glass along with the varied ingredients, the resulting "foam" is about as irregular as it could be, but it IS foamed glass!!!
Infact, I'm so pleased and excited about the results, I think I may just stick with this approach for a while and try to perfect it, so the new thread, though it really is a continuation of the high temperature displacer thread.
Other than the crushed glass, the foaming agents I included were water-glass (sodium silicate), a little activated charcoal and some fly ash from the back of the coal stove. I also threw in some very fine grit silicon carbide powder.
Next I think I would like to try using just crushed limestone as a foaming agent.
I think I actually may have used too much foaming agent and probably heated the stuff too long, as I had taken a peek inside the kiln early on and it looked like the little layer of glass had grown quite a lot, but not being really sure what to do I left it in the microwave and turned it on for about ten more minutes.
I think with the silicon carbide mixed right in with the crushed glass it must have heated up very quickly. Then fell back down and deflated quite a bit, though I'm not really sure.
Unfortunately these microwave kilns don't have any windows to see what might be going on so it's going to be a lot of trial and error to get the timing right.
Also my crushed glass was not uniform. I just tossed some of the left over pieces of glass from my bottle cutting failures into one of those little electric coffee grinder things, so it was not really crushed up very well.
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