Good "filler" for gas forge?

[Chuckspringfield]

Hi guys I'm looking at building my own gas forge and I'm planning on using a small sized helium tank as my forge body. Seeing that I only need an opening of 7-8inches wide and 5inches tall (aprox) I'm wondering what I can use as a filler between the sides of the tank and the ceramic blanket I plan on buying. It would be too expensive to go ceramic blanket the entire way so I'm wondering what, if anything would be a good material to use to build up the sides to my desired size. Would a plaster of paris & sand mixture be acceptable? Any imput is really appreciated! Thanks

[Buzzkill]

Welcome to the forum.  If you haven't done so already, you should peruse this topic before moving on.  It will help you get the most out of the forum.

 

If I recall correctly, the helium tank you refer to has a diameter of about 9 inches.  Two inches of ceramic fiber blanket removes 4 inches from the diameter, leaving you about 5 inches of chamber diameter.  Another half inch of cast high alumina insulating refractory, such as Kastolite 30, leaves you with a chamber diameter of 4 inches.   I'm not seeing a need for any additional filler material.  I certainly didn't need anything else when I used one of the disposable helium tanks for a forge.  For a forge that small the cost of ceramic fiber blanket is pretty reasonable.  Just be sure to rigidize it to keep the fibers from becoming airborne and potentially causing damage to your lungs over time.

Plaster of paris is not a suitable material for the temperatures we achieve in forges, no matter what you mix it with, nor is it very insulating. 

[Steve Sells]

you seriously want to use Plaster of Paris ?  Please read something about it before trying this

[JHCC]

I'm currently building a gas forge from a helium tank with a diameter of about 12". Using the same numbers as Buzzkill, that gives me an interior volume of 7" in diameter by about 9" long, which should be just about right for a NARB running off a 3/4" Frosty T-burner. 

Keep in mind that one of the goals in gas forge construction is keeping the heat IN. Ceramic wool insulates a LOT better than PoP, so trying to save a couple of bucks on insulation will end up costing you a lot more in propane. Frankly, once the PoP falls apart, you will have wasted ALL the money you spent on building that forge. You might as well do it right the first time, rather than going back to fix an expensive (and avoidable) mistake.

[Mikey98118]

You can use K26 insulating firebricks from eBay to keep the efficiency without the high cost of ceramic fiber insulation, but you will pay for that advantage with increased work to build your forge.

Or you can forget using a steel shell and construct a box forge with K26 brick. If I was looking for cheap, easy, and efficient, this would be my choice. To answer the next question, in case you don't ask it, Frosty's "T" burners are what I recommend for use in box forges.