Question regarding gas forge lining.

N

Nateorade

Joined
Aug 15, 2013
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Hello everybody, I've been lurking on the site for a while now, learning a lot. I just have a quick question about the insulation for a home-built gas forge. Do I have to use a refractory blanket such as kaowool, or can I just get refractory cement and pour a solid insulating wall around the inside perimeter of the forge tube?
 
If you want the solid shell, you should use Mizzou or some other castable refractory as opposed to "regular" refractory cement like Satanite or fireplace cement. The claimed advantage of castable aside from it being more rugged that coated wool or board, is that it holds heat better. The downside apparently is that it takes much longer to get up to heat.
 
Yep it will take alot longer to heat up. Even with a good coating of itc100 or similar it still takes a while although that will help.
 
Not only does it take longer to heat up, if you heat it up too quickly it will crack. I have one, and it takes at least 30 minutes to heat it up unless I want to get in a hurry and cause cracking. Once you get the heat up the solid forge will hold the heat better.
I also have a kaowool forge with satanite and itc100. I like the kaowool forge better.
 
What many do not know is that a cast liner still needs to be wrapped in an insulation blanket.
Most times it uses a heavier blanket.
If you just used a liner alone, it would get nearly as hot on the outside as the inside after a while.

The advantages of a cast liner are:
Longer and more constant heat retention and regulation....... once it gets thermally soaked.
No need to use satanite or ITC on the blanket. Just wrap the liner in a couple inches of kaowool and wrap a thin steel cover around that.
Excellent for vertical forges.
Fairly easy to cast.

Disadvantages:
Takes a long time to heat up and soak the liner.
Heavy! A large liner can weigh over 100 pounds.
Takes a larger burner. 1.5" is a good size.
A bit trickier to cure.
 
This is a question I've been pondering as I build my second forge. The inside size before any liner is 6"x6" x14". It's the largest squar tube I could get locally. My initial plan was 2" kaowool or durablanket and a satanite coating for a 4x4 chamber but I thought I had 8" I'd tube, not 8" O.D. (it's nearly 3/4" thick) would a 1" layer of Kaowool with a thick coating of Satanite work and still be well insulated? I'm using a venturi burner but considering going blown.
 
Why are you using square tubing? Round is far easier to get and far better for a forge chamber. If you want a 4" chamber, you would be best to use 8" round pipe and 2" Kaowool. Put a 1/4" of satanite on that and a coating of ITC-100.
If you use your square tubing, you will have to go with 1" wool. That will be OK. I have to say that 14"X8" of 3/4" thick square tubing will be monstrously heavy. A forge shell does not need to be heavy. Stove pipe will work. All it does is support the lining and provide a place for the burner to go through. I have seem forges made with hardware cloth ( heavy screen) shells.
 
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