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Forge insulation suggestion?


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I have a 10 inch diameter pipe I'm turning into a forge. It's about 16 inches long, and I have a 1" forge burner from hybrid burners. I have 2 inch blanket of high density Kaowool type insulation, and I plan on using light weight firebrick for the doors. Someone told me to place a firebrick on the insulation as a floor to stand up to flux.  I feel this would create too I much of a bulge in the forge, so what about placing the brick on the bottom and filling the Kaowool around the brick?


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John my forge is built from a portable air tank 10 inches x 16 I think, so the same dimenesions.  I used to one inch layers of 8 pound blanket.  and I used hard split brick for the floor.  once installed the floor was even with the openings in my door and back wall.  I calculate my volume between 315 and 325 cu inches and use a 3/4 inch Reil type burner.  works for me.  everything inside includeing the brick  is coated with satinite and plistix





If kiln shelf was more available in the area, I'd have use it for the floor.  

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Hello Mikey and MotoMike,

Thank you for the Replies.  The piece I have in my forge is K26 brick, but its way too thick at 2.5" to place on top of the liner.  My concern with placing it in between the liner like in my picture is the gaps that I would imagine I get when I start replacing the brick after flux eats it up.

Like you suggested I found some  1.5" thick K-26 for $5.00 a pop. Which I can throw on top of the liner.  How long do these hold up before you need to replace them? I've also read about people using Kiln Shelves as they last longer vs flux than the K-26 and reflect heat better though I would assume they are more expensive.

After reading some posts I've seen people also suggest Plastech 95 for a more longer lasting (a couple years with daily use) option at $100 +shipping for 50lbs (which I would use a fraction of before wasting the rest)

-mike, that design looks pretty sweet. I'd like a door for my forge but I just have the pipe and I don''t have much skill on the fabrication side. the platform with the black iron pipe is pretty sweet. Can you post a couple more pictures of your frame?



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2 hours ago, JohnH said:

I've also read about people using Kiln Shelves as they last longer vs flux than the K-26 and reflect heat better though I would assume they are more expensive.

High alumina kiln shelves will stand up better than anything else to flux; however, many people have a problem with whatever they use as the forge floor getting covered in flux; at this point, the smartest move you can make is to replace it. If you have a good pottery supply store handy, replacing the shelf is no problem; otherwise, using something that can be easily replaced can trump other factors.

My K26 brick has lots of pretty large holes, which I plan to fill with something like refractory, or maybe Matrikote; you might consider using  such a filler to help protect the brick against flux.

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Check out the Build a Gas Forge attachment on the Forge Supplies page of my web-site.  You don't need the thick pipe for strength, it is heavy and harder to work with.  A 20# Propane tank or a Freon bottle make a good size forge.  You should be able to get an old BBQ Propane tank bottle for free because they have old, unfillable valves or a Freon tank for free from any HVAC shop or any auto repair shop that does AC work I don't recommend that you cut off the ends of the tanks, the curved over metal helps protect the blanket and casting.  I recommend Kast-0-Lite for the castable.

Let me know if I can help you  You can find my contact info on my Profiles page.  I prefer e-mails.

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