Cob: RE: RE: Insulation - vermiculite

[P.Rose]

>Please clue the rest of us (or at least John and I, I guess) in to the magic
>of vermiculite...  Is this some miracle additive to insulate with?

Vermiculite (and Pearlite) are exploded rocks.

As I understand the process you take some specific types of rock,
pulverize them into appropriate sized bits, and heat them in a furnace
until the entrained water flashed into steam, popping the rock like
popcorn.   Among other uses (like hydroponics, and animal-feed (!))
it's mixed with cement to add some nominal insulating qualities.

At least one supplier has a fairly thorough explanation and description
on their web-site at: 

 http://www.schundler.com/

I don't see any particular reason why the stuff couldn't be added 
to cob, although you'd need a lot of it.   On the other hand, 
since you have to ship it in, and since it looks like a fairly energy
intensive product to make, what would be the point?

I still like the idea of stuffing the inner 6" of the wall with
empty beer cans, and then plastering over that.