Insulating castable is DONE

and I am thrilled to be done with it.

After all was said and done, 51 bags of insulating castable were applied to the kiln. 60lbs. per bag. All but 5 of those went on the rear chamber.  That’s 1150kg/2760lbs of castable sitting on the rear chamber.

First, the arch over the rear chamber door.

Next, the front and rear views of the rear chamber. Since I couldn’t do it all in one day, there are decidedly obvious lines where one day’s work started from the previous’ finished.

This rear side, I made the mistake of trying to work my way down from the top, then castable started falling down as the angle got steeper and steeper. Started from the bottom and worked my way up, but had problems with the mix sagging and settling, so set it down for a night and came back in the morning. The darker strip you see here is the last bit I filled in with. Makes the rear chamber looks like it is in the advanced stages of elephantiasis.

Thermocouple hole.

I went back and repaired the patches that hadn’t filled in properly around the top spy, as well as the stoke, getting rid of the chisel marks from Monday.

It’s hard to see from this angle but that castable is a full 6 inches thick at the stoke, and under that is a layer of fiber. That back wall is so well insulated, the stokers might have to wear coats and long underwear to keep from getting frostbite….

The bottom right section was done as sort of an afterthought (and looks like it) because I had extra mix left over and needed to put it somewhere. It will help support the right side of the wall, I think.

One of the trouble spots discovered in the first firing was where the arch met the front wall. As the kiln got hot, the arch expanded and created a place for cold air to leak in all up and down where the front wall meets the arch. I draped fiber down both sides and covered it up with castable, so now even with the expansion, the resulting spaces created will be covered and pretty airtight, I hope.

Next job is to go in and seal up the cracks in the first chamber covering mix, then apply some more over the top. I have clay left over from digging to make more mix, but my cousin came over the other day with some premixed red mountain clay/mica/straw/sand in a 50 lb. bag @ only 200 yen per bag., cheap. Normally it is used as underlay for roof tiles, but it may be just the thing for this job too.