[Cob] vermiculite, pumice, perlite suppliers?

[Shannon C. Dealy]

On Thu, 22 Sep 2005, Amanda Peck wrote:

> What's the difference between masonry grade and gardening grade, (which might 
> not be available in the gardening sections of the stores, but rather through 
> greenhouse or professional garden suppliers)?
> ......................
>
> Shannon wrote (snipped into nothingness)
> masonery grade perlite

Horticultural grade perlite is open celled in order to absorb and retain 
water for propagating plants, masonery grade is closed cell for use as 
insulation.  If you use horticultural grade for a stove (as I once did 
years ago), it will suck up tremendous amounts of water when you are 
trying to mix it with your clay slip (if you don't use lots of water you 
won't be able to get the clay slip to coat it), and it will take forever 
to dry out, during which time your stove won't be working as well as it 
should (after 50 hours of almost continuous running on my stove at the 
time, a large percentage of the perlite was still wet, though I was 
running a thicker insulation layer than normal).   Don't use horticultural 
grade perlite!

Shannon C. Dealy      |               DeaTech Research Inc.
dealy at deatech.com     |          - Custom Software Development -
                       |    Embedded Systems, Real-time, Device Drivers
Phone: (800) 467-5820 | Networking, Scientific & Engineering Applications
    or: (541) 929-4089 |                  www.deatech.com