Currently I am using silica flour in place of sand. This is expensive in that the sand is mostly free and the silica flour has to be shipped. Need to experiment to see what replacing some of the silica flour with sand will do. Later. For now lets do this furnace.
Scaled up the formula, made about twice what I needed. Just to be safe.
Sifted everything but the silica flour using a flour sifter. So the perlite is fine.
The powder is tumbling to dry mix it. Debating if I should mix it all with the power mixer or mix smaller batches by hand in a mixing bowl. Trouble with the power mixer is the corners never get fully wet. But I guess thats OK because I can add water as I go because it was well mixed dry. I think I am going to use the power mixer because I have never had a batch crumble using it and the operation will go faster.
The core has been prepped by removing the PVC spring clips and wrapping with suran wrap.The clamps ensure the can stays in place and holds the PVC core centered.
The wall thickness is .8 inches. Will have to see how that works out. Next time I may split the can so it can be easily removed and reused. Then embed the thing in aircrete.
I need to learn to let the mixture rest for 5 minutes or so after power mixing it. Need to beat this into my head. If I don't it ends up too stiff and maybe without enough moisture to hydrate what needs hydrating to set. Sigh. Maybe it will come out anyway if I keep it wet, think I tried that without much luck. In two weeks I will dry it out, at that point I will know if I need to recast it. Sort of got used to casting little trial bricks. Not quite the same here.
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