Ceramic Fibre - density and thickness?

[jonv]

My dome should be done in a few weeks so I was wondering what I should order to insulate it. I noticed that CF blanket comes in different densities and thicknesses, so I have two questions:

First, what effect does the density of the insulation have in practice, and what should I be looking for?

Second, I am planning on four inches of insulation in total; is it easier to work with four layers of one inch thickness or two layers of two inch?

Thanks in advance for any thoughts

[jonv]

I've been offered some at 96 kg/m3 - is this ok or would it be better to find some with 128 kg/m3?

[JRPizza]

The blanket I used was 96 kg/m3 (~6lb/ft^3) as it was available without special order and close to half the price of the 8lb/ft^3. In hindsight I kinda wished I had used the heavier blanket as with all the work the oven takes the extra expense would have been "in the noise". Our oven still performs well but if you use the thicker stuff you will never have to wonder "what if". If I ever think the oven needs more insulation I'll either add some vermicrete, or just build an enclosure and put in a bunch of loose insulation
It's possible that 4" of the lighter blanket is as good as 3" of the heavier - attached is a spec sheet for the Inswool I used so you can compare the thermal properties.

[jonv]

You're right about extra expense. The project has been so expensive and time consuming already that I don't really care what the blanket costs - I just want to make sure it works as best it can. Perhaps I should get the more dense sort...