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Question on castable refractory

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Hello again,

I've had some time to do research on different kinds of refractory material and I really like how the Kast-O-Lite 30Li sounds at first glance.  I was wondering if I should coat the Kast-O-Lite in an IR refractory like ITC-100 (a little too pricey for me...) or Meeco's Red Devil 610 refractory cement (well with in my price range but unsure about efficacy).   I have attached a ROUGH drawing of the front of the forge.  Here is an overall idea of what I'm shooting for:

Brushed stainless metal trash can for the shell (H=12" Dia=8")

Hoping to do 2" of Kast-O-Lite to make a chamber of about 4" x 11" and have an exhaust port at the rear about 1.5"

Hard fire brick as the floor (4.5"x9"x1ish") No refractory on these.

Planning on having the burner pipe cast with the material then holding it in place with bolts.


What say you fine folks?  Any and all wisdom is greatly appreciated.  I'm hoping to get this bad boy up to welding temps but we'll see.

As always thanks for all the advice.


Big Jim

(p.s. please excuse the horrible drawing in the image... I swear my 6 year old can draw better than me)

Oh and I was also thinking of using the lid as a door to make the front opening smaller to retain more heat when I'm trying to weld.


Big Jim

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Big Jim, 

I am far from the expert of many of the others, but I see a couple of problems.  First my understanding is that red devil is a IR coating, rather a refractory cement used to hold bricks together.  I would check with Wayne County, he has some alternative products that are less expensive alternatives to itc.  Second I would not use the fire brick, it is a fuel hog.  I would either cast the floor with your kast-o-lite or track down a kiln shelf.  Again not an expert take it for what it is worth.


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Jim: Kast-O-Lite is better than most hard refractories it has some insulating qualities but you'll be a LOT farther ahead to make an outer liner (backer) with ceramic blanket refractory, Kaowool is a brand name and shorter to type so . . .

Even 1" of kaowool will make your forge MUCH more efficient but two 1" rigidized layers is pretty much the current consensus for a good backer layer. A flame face or "inner liner" of 1/2" of Kast-O-Lite 30 li is durable and high temperature enough nothing else is actually necessary. Forget the fire brick floor level it with a little kaowool and plaster it with Kastolite will make a more durable and FAR more efficient floor.

Kast-O-Lite 30 is a 3000f. water set, high alumina bubble refractory. This means you work it like concrete, add water mix and use we can talk about different ways to apply it if you like but later, okay? High alumina means forge welding fluxes won't effect it, welding temperature borax eats fire brick like hot water on hard candy, soft insulating brick like a sugar cube and unprotected kaowool like cotton candy. KastOLite isn't phased at all, zippo. 3,000f is it's max working temperature not counting the safety factor so it's safe from your forge burners. The bubbles are evacuated silica spheres that make it light weight and give it decent insulating properties. The matrix think cement in concrete protect the bubbles from flux.

A zirconia silicate kiln wash of one kind or another will really improve the efficiency by collecting and re radiating IR while adding another layer of very protective stuff between the fire and the kaowool. ITC-100 isn't really the best stuff for a forge kiln wash, it's 70% zirconia and 30% kaolin clay. Our forges don't get hot enough for long enough to vitrify kaolin clay (porcelain) so it's just there like a thick layer of chalk it rubs off. ITC products sells it for large industrial furnaces as a wear item that gets replaced with regular maintenance. 

There are products that are more reasonably priced and work better, MUCH better in a hobby forge. Plistex and Metrikote being two I can remember. both are available in reasonable quantities from Wayne Coe a regular poster here. Heck he sells smaller quantities of everything you need to build a gas forge for reasonable and ships. His forge plans are a sound proven design, I'll bet he'd make and ship you a "kit."

If you do some reading in the "Forges 101" and "Burners 101" threads all this is covered well with explanations other opinions some silliness and . . . It's a good read, there's no reason for you to try to figure this stuff out it's been done and tested for decades. Honest. We offer you our mistakes so you won't have to make them yourself.

Frosty The Lucky.

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