Mixing Castable Refractory

J

John Hoe Handle

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May 3, 2017
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I have cut and painted a 20lb propane tank for my first propane forge. I have 2" keowool and 10lbs of greencast 94.

Can anyone tell me the proper mix (water) and how I should apply to the keowool?

Thanks,
Mark
 
I'm not familiar with your Green-cast, but the specs say it is a high alumina refractory. If it makes a smooth paste when mixed with water, then it probably will work. If it is coarse and "gritty", it may not.

Normally, people use Satanite or a similar refractory to coat the wool. Mix with water to a thick paste about like a milkshake. Spread on with a spatula and smooth out to a 1/4" layer. Let dry and then cure by slowly firing and cooling until you reach full heat.
 
Looking at the instruction sheet, it seems it is probably a water-setting refractory and undergoes its permanent change within a short time of the water being added.

I think Satanite is more likely to be a clay-based refractory and just dries into place before being permanently changed during firing. It's worth pointing out that I'm in the UK and have no experience of Satanite. I am basing this assumption on a half-remembered discussion with a smith who uses Satanite for hamons and I'm fairly sure he keeps it wet pretty much indefinitely in a sealed container.

If I'm right, I'd expect the two materials to behave very differently.

Instruction sheet for the Greencast 94 is at:

http://www.37710.samplesite.gbr.cc/cdata/37710/docs/1698591_2.pdf

The only discussion I've had with a smith who has actually used Greencast 94 was to do with its excellent flux resistance. I had the impression he was only using it for the forge floor.

If you are intending to apply it to the roof of the forge as well as the floor, I think you might need to make some of it up as you go along. I think the floor, and probably a short way up the walls, should cast in place pretty much as per the instruction sheet.
 
My recollection is similar to Tim Gunn's in that I thought it was for floors only. It's kinda like making gravy, just keep adding a little water at a time until you get the right consistency.
 
You might try to get a rigidizer I got mine at my local pottery shop. My latest (and second ) forge has a castable on wool I started on the sides and bottom (I use a kiln shelf on the bottom) then I laid the back of it on the ground and worked my way from back to front.
Gilbert
 
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