Robert P : Welcome to Permies.com, And a Big Welcome to the Rocket And WoodStove forum threads! Good Question - I take a couple of bites >
We like Perlite and Vermiculite for their individual insulating properties - especially when they can be poured into and fill a cavity. When We must use them and any other material to rigid-ize them,
like when well make a Heat Riser The materials we use - most often a clay slurry - we end up reducing their insulating value ! This is because we fill or partially block their insulating air spaces.
Most people have reported that we use less water building with perlite which is more stable and less subject to failure due to handling and general abrasion both during construction and use, less water
reduces drying times also !
In garden use We are just looking for the ability of ether material to hold water, It is possible that vermiculite has a slight edge initially, however Vermiculite will tend to crumble away -the more the soil
is worked.
Perlite comes in 2 grades, 1 for people to use in gardens and greenhouses and another grade that is hard to find in some regions that is more suited for construction and insulation uses ! Usually the
Perlite for gardening/greenhouse use is clearly labeled on the bags as designated for G/G use !
Tens of thousands of Rocket stoves ,and
Rocket Mass Heaters have been made from Both materials, often the use of one material over the other was made because only one material or the other was
the one that was locally available or cheaper !
Hope this helps 1 As always your questions and concerns are welcome and solicited! Fo the good of the crafts ! Big AL
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