Thread: Refractory

A question in another thread about kaowool reminded me I'm likely going to have to re-line my forge this fall. Repairs are definitely needed, so I'm thinking about just re-doing the whole thing.

I currently have 2" of kaowool (or another similar brand - can't recall) ceramic wool, coated with a refractory cement I bought from another smith here in Ontario. It isn't as good as satanite or ITC-100, but it seals the wool and seems to reflect at least some of the heat.

So my question for you guys is: what to you coat your ceramic wool with in your forges? It satanite or ITC-100 really worth the cost? Any other suggestion?

Thanks,
Kris

In my talks with Charlie Lewis he said to use kaowool first, satanite and then use itc-100. In my case however I'm stuck with using only 1" of kaowool.

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Hm... hadn't thought of doubling up the coatings like that. Interesting idea - thanks.

Several small forges I've built have had the ceramic wool liners using 1 inch material. They work fine with the venturi burners I have. I think I remember using a slip refractory coating called Macote (an ITC-like infrared reflector). My opinion at the time was that it seemed to partially collapse the "loft" in the cerowool. My thinking then was that the loss of insulating thickness would affect controlling the heat, e.g. better loft equals better thicker insulation and thinner insulation would result in conduction losses to the shell and not into the work. So, I quit using it. I'm cheap and when I stick a thermocouple into the fire...it reads "hot". No ITC or Satanite or additional layer of wool made it any hotter. The refractory suppliers are always willing to sell you more stuff.

I've not noticed any fibrous discharges, but I do wear a mask while constructing these things and during the initial firing. Once a refractory is fired it pretty much sets into place and doesn't shed after that. I'm more likely to die from lung cancer from my parent's years of chain smoking anyway. Your paranoia may vary.

I also tend to use a hard castible refractory for the floor of the forge and the ceramic wool for the dome so it's not a complete internal wrap. The fluxes I use on pattern welded steels destroy the wool insulation. And there are ad infinitum discussions on-line about how gravity will cause the wool to thin out over time.

My suggestion is to treat ceramic wools and refractories as consumable items. You will bang tongs around in there, you'll drop hot parts, stuff will take a wrong angle despite your best grip and jab the inside of your nice pretty forge and bugger things up. They will degrade and you will have to rebuild your forge lining at some point. That's really the best thing about learning to build your own forge for yourself. You will already know how to repair it, if it fails.

What you are really doing is controlling the heat lost to the environment. If you are forging at 800C you may not lose more heat to the environment than you are putting into your work. If you are welding steels you may want more heat trapped in the forge and need more insulator. It depends.

Early morning thoughts I guess.

I have used Satanite for the small home brews that I put together, also smoothed out the inside of my Atlas forge nicely.
It is worth the investment. I keep a coffee can full on hand for repairs and clay coating blades.

Whoever took over Ellis custom knives, I forget the name but high temp tools .com. great service and fast. I just bought a couple pounds again.