Forge Building (insulation) Question

T

Twistedbrilliance

Joined
May 13, 2014
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Hi guys,
I'm in the midst of planning out my first forge build. I plan to make my forge out of an extra propane tank that I have. I got the idea from a youtube video I saw. The size seems perfect and the design is simple to make. I have a few questions though.
I have found a supplier close enough to me where I can buy 2300 kaowool which has a recommended max temperature rating of 2000F, and comes in 1" thick by 24" wide and cut to needed length at a good price. I plan to do two layers to make it 2" all around and use a slab of fire stone or ceramic fibreboard as a floor within the forge.
I haven't picked out what design of burner I will install yet as I have more reading/research to do first. I'm not sure what kind of temperatures it will reach inside and whether the double layer of 2300 Kaowool will suffice or if I should order 2600 kaowool I have found online (which I believe has a max rating of 2400F) but will cost me 3xprice per sqft.
 
I was under the impression that the "2300" in 2300 kaowool stood for the temperature rating of the product, I could be wrong

I would make one suggestion, I built a propane tank forge and I used a 20LB cylinder, and I wished I would have used a 30lb, the 20LB isnt quite deep enough
 
You probably won't be happy with just Kaowool.
It's made as an insulator, and doesn't reflect (or is refract the right term?) well enough to get you welding heat.
I made my forge ten years ago with a propane tank and two layers: an inch of kaowool on the outside and an inch of Durablanket on the inside, and I keep a light coating of Plistix on it too, to stabilize it, though the Durablanket alone works great, it sheds bits that blow out and can't be good to breathe.

Couldn't figure out why my first forge wouldn't weld, until a kindly blacksmith explained about what Kaowool is.
I opened both ends of my forge and walled them with stacked firebrick- it's used daily for blacksmithing work, and frequently for blade work- damascus, HT of simple steel, etc.
Fire brick floor.
 
I believe you are confusing the word ceramic with refractory.

Inswool/Kaowool is a mineral wool insulation. It provides high insulation value for the forge shell. It should not be used alone in a forge.
Satanite is a refractory cement that you coat the inswool/kaowool with. About 1/4" of satanite over the wool is normal.
ITC-100 is a reflective refractory coating that is painted over the satanite. It could be used alone, but works much better over a base of satanite. The ITC-100 coating is pretty thin - 1/8" is normal. Build it up in several thin coats for best results.

The satanite needs to be fired before the ITC-100 is applied, and then the ITC-100 is fired.

For the floor, any flux resistant material works. The normal floor coatings are Bubble Alumina and high temp refractories like Mizzou. Insu-board also works. Some use fire bricks, but that is usually in a larger forge.


There is also cast refractory that is cast in a mold as a 1" thick solid tube and used as the forge lining. This needs to be wrapped in a couple inches of Inswool to work as a forge. A coating of ITC-100 is a good final inside coating.
These type forges are very durable, but are large and heavy. They are good for dedicated da,mascus forges or production shops, but a lot of work and expense for a small shop.
 
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