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Fire clay (uk)


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I now have most of the parts for my "foundry" build, my ceramic fibre blanket arrived yesterday along with adhesive which can be watered down slightly to make a rigidizer


I've read so much about refractory and flame face recently that I've got a bit lost, it seems to me that kast-o-lite 30 on its own (after rigidizer) would probably be enough for the small amount of use the forge/foundry will get....


BUT it's difficult to find here in the UK and when you do, it's expensive. The old engineers here often mention fire clay, it's cheap and easy to find here too. I can get it in powdered form and I'm starting to wonder if I could mix it with (for example) 50/50 water and rigidizer to a thick paint consistency and paint it on in a couple of coats to protect the ceramic  (to a certain extent). 

Does it have a chance or am I barking up the wrong tree altogether? Any other suggestions would be much appreciated

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Hi Rich,

As a fellow Brit, you're going to find it tough to get Kast-o-lite30 over here.

Having read the complete Forges-101 and Burners-101 threads (yes it takes ages, but there is so much invaluable information from very experienced people, it would almost be crazy not to) I came across an alternative Flame face coating method.

A forum member called D.Rotblatt had been doing slipcasting of metals, and had been making and using a high-temperature slurry to coat the inside of his ceramic blanket for decades. Unlike Kast-o-lite, which sets to a rigid, concrete-like finish, this slurry is mixed up in a pot and painted on over the rigidised blanket and then heated to
set. You need to paint and set a good few layers to build up a protective crust of Flame face. 

This slurry is a mix of Zircopax(Zirconium Silicate powder) and a Colloidal Silica liquid. When it dries and is heated, the Zircopax acts like an Infra-Red re-emitter, and radiates heat back into your forge. It is not as strong a coating as Kast-o-lite30, but it heats up very fast (so is cheaper on gas), is easy to patch, will protect the surface of ceramic blanket and soft fire bricks (which are damaged over time with too much direct flame impact), and it is pretty cheap. Ideal for a hobbyist!

Here's a link to a thread where I built a forge and used and tested this Zircopax slurry with great success.

The searches for coating materials:

GOOGLE: mbfg fumed silica                                      (Can be mixed with water & food colouring to make your own ridgidiser)

The searches below get you to places you can buy the Zirconium Silicate powder (Zircopax) and the Colloidal Silica solution (Morisol x30).

GOOGLE: scarva en gb zircopax

GOOGLE: ulster ceramics morisol x30

If you want to know more, then let me know.

All the best,


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Before we knew about Kast-O-Lite 30, we built our forge using Satanite over the blanket for the hard face then a coating of Bubble Alumina for the re-radiating coating. It has worked well for us. Satanite is a powder mixed with water designed for forges and is much better than fire clay, which we had on hand due to the pottery side of the business. Here is a link to the build. Sadly the early pictures were lost but the thread is still relevant.

20 pound propane tank forge in progress - Gas Forges - I Forge Iron

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