Kaowool

[Len Foley]

I am building a melting funace using a stainless steel LPG tank from a car.
I was going to line it with refractory cement but I was given a quantity of Kaowool.
If I use this, to hold it in place can I line it with stainless steel sheets. I have a quantity of punched sheets like pizza trays that I can form and weld in place. I am melting aluminium.
If I can use this how firm should the Kaowool be packed?

What a wealth of knowledge this forum is.

[Eurisko]

Don't pack it too tight.

From what I've read, air is a poor conductor of heat, and you don't want to compress the air out of the fibers. What is important is the thickness of the insulation. I'd suggest 3 to 4 inches minimum.

I built an electric kiln using 4 1/2 inch lightweight firebrick surrounded by an inch of ceramic fiber. The aluminum skin is warm, but not hot to the touch.

Not bad when the inside temperature is a sizzling 1400 deg.

[DukerX]

Lining the inside of your furnace with stainless steel might not be a good idea unless you're going for an argon flooded electrically heated unit, as the stainless steel oxidises very rapidly at elevated temperatures. TIG welders use Argon gas in the torch and also as a backflood to prevent this. If it's a combustion type furnace, I'd say forget it.

[adamziegler]

Is it loose kaowool, or the blanket?

The blanket can be self supporting. The blanket can be attached to the walls of a furnace with ceramic buttons. The batting/loose kaowool should be stuffed behind something like a hotface. A hotface is generally made from refractory material.. like the refractory cement you mentioned.

You can also purchase rigidizer that I have seen some people apply to the batting to hold it in place. I am not completely aware of how this is done. Rigidizer on the blanket also works to help stiffen it up.

[Len Foley]

The Kaowool is in blanket form - about 15mm thick.
I have heard of the rigidizer but also am unsure of the process

[adamziegler]

If it is a blanket, you just paint it on or spray it on the surface of the blanket facing the crucible. Again however... the blanket is probably stiff enough to sit in place as is.... without any attachment to your outer shell or rigidizer needed.