Forge construction question

Blue Sky

Blue Sky

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Jun 16, 2002
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I am very interested in using Mizzou to cast a medium-small forge, to be used for small-scale heat treating. I understand that it does not insulate as well as Inswool, but for various reasons it still presents the best option for me at this time.

My first question is, if I coat the inside with ITC-100, would this significantly improve it's heat retention? ITC-100 is used to cover and protect Inswool, but it is also a heat reflector, correct?

Second question: How durable is Mizzou when cast? Does it chip or crack easily?

Third question: How much mix does a 30 lb. bag of Mizzou make? A 2 gallon bucket full, 4 gallons...?

Any info, opinions and advice is appreciated.
 
You will use a lot of and I do mean a lot of gas to get your mizzou lined forge up to temp. Not something I'd want in a heat treating. Kwool is much more responsive.

I built one. 3 inches of Mizzou, it took 30 to 40 minutes to come up to forgeing temp. I could not weld in this forge with the same burner that I used with the kwool.

Put a 1/2" of mizzou over kwool and you might have something.

Mizzou is very tough, flux does not eat it readily, I never beat on it but normal forgeing use it will last indefinitely . I would use some type of shell to hold te forge together even if its only expanded wire.

In my opinion the best of both worlds is a forge lined with kwool, 2" or so, coated with kwool rigidizer, and the bottom half of the Horizontal forge coated with mizzou or blu-ram.

In a vertical forge its the same configuration.

You will get more and faster heat from the kwool and the Mizzou or blu-ram will protect the forge against flux degradation and hot work.
 
The only thing that I can add to Sweany's good information is to tell you that Mizzou has a density of about 140 pounds per cubic foot. If you tell me the volume of the forge shell that you want to cast, I can tell you exactly how much you'll need. You'll then need just a little over that amount to account for any mixing losses.

Adding ITC-100 will help a little...better with it than without. However, you still have a very dense media directly in contact with your forge shell which radiates heat away. When you use Mizzou, you loose some efficiency, but gain a great deal of robustness...it's a trade off.

:)

-Darren
 
Thanks gentlemen for the detailed and informative replies. I was hoping my idea would give me the edge I needed but I see now it won't. I've been thinking it over a while and decided I'll have to budget for a more conventional (and efficient) forge design. Thanks again for your help!
 
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