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Kast-O-Lite 30

Castable refractory 

Price $15.00 per 5 pound plus shipping.

Shipping will be calculated on your entire order of materials.


Contact me PM with your order.


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  • 3 weeks later...

Hard refractory provides armor against both heat, flame and mechanical damage being poked and scraped by work going in and out. Kast-O-Lite 30 works well in around a 1/2" layer but some folks like 1/4",  others folks like more.

Approximate mixing is 1.2 gallons per 55 pounds or 2.79 ounces per pound.

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From Frosty

The best cure method according to the maker is to treat it just like hydraulic concrete. It water SETS, it does NOT DRY. These are two entirely different things. Read up on working, and curing a patio or shop floor. Portland cement, concrete and Kastolite set and cure very closely to the same in time and steps. Kastolite refers to concrete procedures as THE way to cure Kastolite for maximum strength and temperature rating. 

Except for water % details the comparison is across the boards close enough to the same as to be interchangeable. 

So, when it sets close it up in a 100% humidity atmosphere for up to 7 days. We do NOT need a max strength cure, we aren't subjecting it to the kinds of forces temps and atmospheric changes a commercial forging or scrap furnace does.

Frosty The Lucky.

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This is not refractory cement.  It is refractory insulation.  Manufacturer does not list IR reradiation characteristics, but it is lighter colored than Rutlands (which shouldn't be used as a forge lining in any case) so will likely reflect more IR.  Material is also 56% alumina, which is also a good indicator IMHO.  Data sheet appended.



Maximum Temperature 3000°F

Material Required 90 lb/ft3

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Welcome aboard KingCrowleyInc., glad to have you. If you put your general location in the header you might discover how many members live within visiting distance and a LOT of info is location specific. Do you have a preferred form of address we can use? Your logon is pretty cumbersome and if we have to make something up, you'll be stuck with it.:P

Furnace cements and mortars are NOT USEFUL FLAME FACE FURNACE LINERS. They are formulated to bond masonry together and are very short lived in contact with flame. Propane especially is VERY chemically aggressive and more so as a 3,000 f. flame. 

We're not harshing on you but terms can be critical. This instance is as significant as the difference between gasoline and diesel when you fill your vehicle. Using mortar or cements as forge liners is an urban myth almost as utterly wrong as the one about using plaster of Paris and sand, that last can be dangerously BAD. 

We're doing our muddling best to help get a uniform terminology in use around the world.

Frosty The Lucky. 

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  • 4 weeks later...

Copied from another thread


Kastolite is NOT easy to mix, you can't just stir it, it'll set up before it's thoroughly mixed. I knead it in a stainless pan with a heavy stainless serving spoon and all but do hand stands on it in the process. It's the crushed aggregate that makes it such a PITA, the broken particles don't slide past each other, they catch and key together. Visualize a sack of marbles compared to a sack of jacks and how much different they'd move.

I had to go a LITTLE over recommended moisture content but we don't need maximum characteristics from the finished refractory. Just don't get carried away with the water, just a LITTLE.

Nothing will make it spread smoothly, that'd be like rolling dominos, it just isn't in the cards.


I also do my mixing in a pan, but I measure everything out by weight first, then sprinkle the water over the entire surface, and finish by chopping it together with a drywall knife. That gives a uniform distribution of moisture throughout, and I know I have the proportions correct. 


KOL does NOT dry! It cures like concrete it needs a time at 100% humidity, 24 hrs. Minimum, 7 days for full strength.

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  • 3 months later...

Short answer: use basic math to determine the volume of each of the cylinders of different material you want to install, then use the installed material density from the manufacturer in the case of the Kastolite or the material volume in the case of the ceramic fiber (wool) to figure out how much you need.  Add 20% for a safety factor and bob's your uncle.

Even shorter answer: your forge interior size is around either 939 cubic inches or 704 cubic inches, depending on whether you cap the ends with the 2" of wool and 1/2" of castable, as you noted.  This is likely too large a forge, you should consider a redesign (though for full disclosure, my forge is currently right around that size also, but I use a commercial burner).

Long answer (for ease I'm assuming cylinders with flat ends, though I'm aware that most propane tanks have hemispherical ends) : 

For the wool you will need (2) end caps, each around 12 x 12.  The wool typically comes in 24" widths, so 2' for those assuming you are using 1" thickness.  The first layer (assuming you are still using 1" thickness) you need around 40" of length.  For the second layer your diameter decreases from 12.73" to 10.73".  This means the circumference decreases to 33.7", so you need that length for the second layer.  Added up you need around 24" + 40" + 34"= 98".  With a 20% safety factor that is 118", or just under 10'.

The volume of Kastolite you need I will base on a 3/4" thickness for safety.  Again the end caps are now 8.73" in diameter.  This gives a volume of around 45 cubic inches for each cap, or 90 cubic inches for both.  The forge walls will be the cylinder formed by the inner surface of the wool minus the open forge interior cavity.  So a cylinder of 8.73" diameter less one of 7.2" diameter.  Lets figure the wall length is 20" - 4" - 2"= 14".  This gives a volume of (60 - 41) x 14 = 266 cubic inches.  Add to the 90 cubic inches in a final requirement of 356 cubic inches.  Per the note above, the material needed is 90 lbs/ cubic foot. 356 cubic inches is 0.206 cubic feet.  So you need around 18.5 lbs.  I would buy extra for doors and the like, so around half a typical 50# bag.

Note: I hope from this you can do the math yourself after redesigning a smaller forge.

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