Stirlingengineforum.com

VincentG wrote: ↑Sun Oct 22, 2023 6:55 pm Maybe you can confine the clay to some sort of mold while firing it?

Possibly, though ceramic usually shrinks when fired.

At this point I'm just intrigued with the possibility of firing ceramics in a microwave in minutes instead of hours.

It looks like, just using a cheap 1000 watt microwave and $30 microwave kiln small parts can be fired in five to fifteen minutes.

Probably about 7 minutes would be ideal for most parts. More like 12 minutes for really extra hard stoneware.

What seems crucial it preheating to get the clay perfectly dry. If absolutely dry there really doesn't seem to be any problem with ballooning or explosions. As far as I can tell, the results of firing five to ten minutes in the microwave kiln produces results equivalent to several hours or days using conventional firing methods.

I made this kind of ornament to try in the microwave kiln by pressing a leaf into some clay with a rolling pin.

But, it's fall now and getting colder, so, tonight I started up a fire in the wood stove for the first time this season. So I'm seeing how this will fire in the wood stove.

Ultimately, the microwave kiln will be too small for any larger power producing engines.

If this thin flat ornament turns out OK, I may use the same method to finally make a displacer for the Brent Van Arsdell Limited Edition restoration I've had on the shelf for quite a while.

https://www.stirlingengineforum.com/vie ... f=1&t=5401

Even that would be too large for the little microwave kiln.

Firing time test results video:

https://youtu.be/VfaysuxntMQ?si=aL8NVTt85q1F6WAI

Finally getting around to setting up and test firing my big kiln.

At the highest setting it can apparently draw nearly 50 amps (220 volts) so it required new breakers and special wiring but it seems to be working!!!!!

https://youtu.be/wodpvttwJO0?si=5cUPnmp7GYr-WmvC

I came across a couple videos, (or rather, I think the YouTube or Google algorithms or AI put them in my feed based on my interests perhaps,) showing an apparently very old method for improving the quality of "wild" clay (basically dirt) using organic polymers from rice water.

https://youtu.be/HbLdNKM9y68

Later experimenting, it seems just about any organic starch will do

https://youtu.be/vBAzZHIFb0o

I can't personally vouch for the process as I haven't tried it, but I think it makes sense and I'll be doing some experiments with our own local glacial clay.

This local clay seems quite plastic and workable on its own, passing the coil around the finger test with flying colors, so I may not be able to improve upon perfection.

Either way, I thought it interesting and potentially useful for somebody trying to make ceramic engine parts from whatever "dirt" they might have available.