The fiber clay? Don't know yet. It is just out of the oven, where I only warmed it to help dry it out.skyofcolorado wrote: ↑Fri Apr 28, 2023 8:16 pm What's the final grams per cc of that substance after firing? Does it take a direct torch flame okay?
It came out of the oven slightly misshapen but was easy to sand down nice and flat
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I will, of course, post the results once it is fired in the kiln, assuming that works, and the displacer survives.
At this point, I found that the material I more or less randomly mixed together on a whim to coat the silicon carbide is looking like a potentially very promising material for use as a displacer.
Often I have found that refractory cement of various sorts tends to crack and eventually crumble with repeated heating and cooling, but not this stuff (so far)
There was a left over glob of the 50/50 Plaster of Paris and Perlite (with a little water glass) mix that dried out on the bench over the past few days. It seemed quite lightweight and surprisingly strong, so I went ahead and subjected it to my usual torture test:
https://youtu.be/0Oc1qBVWkvs
I've made up various plaster and perlite mixtures before, but this time I really wanted to avoid any cracking or shrinking for the microwave kiln.
I had some previous experience with making concrete block. For that, the concrete has to be mixed up dry as possible, really just enough water to dampen the mixture without it being at all liquid or runny, that way it can be packed into a form and the form removed immediately for use in making the next block. These dry mix concrete blocks do not shrink much at all, or crack when drying, as, for the most part they are practically already dry to begin with.
So I thought I'd mix up the plaster and Perlite in the same way like an almost dry concrete block mix.
The wet plaster and Perlite mixture was about the same consistency and appearance as cottage cheese. If there is too much water the perlite will tend to float to the surface.
The only real problem with such a dry mixture is that it sets up very rapidly, right in the bucket if you don't keep stirring or don't use it fast enough. It sets up almost immediately.
The little bit of sodium silicate seems to make it set even more rapidly.
With the first batch I diluted the water glass in a cup of water and added that to the dry mixture first, then added enough plain water to bring the mixture to the right "cottage cheese" consistency while stirring.
When I made the second batch, I poured the cup of water with the tablespoon of sodium silicate in last and as soon as I poured in the cup of water with the waterglass into the already wet mixture it set up in the bucket and I had to add a little more plain water and give it a good stirring to loosen it up again.
This seemed very strange, as I poured in this liquid water + water glass and instead of getting more soupy, the mix set right up so rapidly it was unbelievable. The waterglass seemed to act as a catalyst similar to a very rapid setting two part epoxy.
Now I'm thinking of trying the same mixture with some foam mixed in to make it even lighter
