Vermiculite

Vermiculite is a very resourceful  product, it is safe to use, it  is even used as a food supplement for bovines.
Vermiculite can be bought in ready made sheets in various sizes and thicknesses ,it also comes in brick form.
Vermiculite can be used in very hostile and hot environments .
Generally rated around 1,100c - 1,200c it has many uses. (2200f)
Vermiculite is also available in grain form and is used extensively throughout Europe as a house insulator and as a soil additive.
However, I have not been able to work put how the high temperature board is made of what the binding additives are.

last year i tried to make some castable slabs with vermiculite , i looked at this pdf called " vermiculite in the construction industry" , they mention refractory potassium silicate  is used as a binder , i was nt able to source any and tried waterglass type silicate , there is --"newtonslab" ---he was into this , even making his own silicates , seems the mix has to be pressed while low fired or cooked almost , i had thought of making a steel box type mould  that could be pressed down then wedged closed--not bolted--and fired up in a home made kiln of sorts---but my elaborate plans were getting wildly out of hand ---i would have needed something bigger than my little forge firebrick  oven , so my as cast and cooked on the coal forge attempts  only ever got a crumbly easy break product , that fell apart in my woodstove, ----nothing close to what you have made so far.

i did find out that mica has high potasium silicate and aluminia content which is used as a clay in pottery and in making glazes , it can take 800 C and  is thermal insulative , perhaps usefull as a binder in vermiculite mix

reading back over that pdf on the use of vermiculite in construction ,somewhere it states that an organic binder is used in the manufacture of the boards , the only one i can think of is diatomaceous  earth ,which is used in some cement mixes in a powdered form.

Just a heads up - I have read that vermiculite is geologically found in conjunction with asbestos. A friend here had to have the vermiculite insulation removed from her old home because of this contamination.

If you're using this in a stove, if it is bound together, the asbestos may actually be an asset, but I don't want it going up my flue, and I would want to wear a good breathing mask  while working with it.

This may be a west coast of North America geology characteristic, and I am aware that some forms of asbestos (finer ones) are far more dangerous than others, but it's something to research further.

Vermiculite its self does not contain any as asbestos, I think there was one particular US vermiculite mine, in Montana I think, that some time back, produced a load of  contaminated vermiculite.
It was found to be contaminated with asbestos  dust.
However I believe all the mines nowadays are monitored and asbestos  free, in 2000 the UK and EU banned the sale of any form of asspesdos.
So it would be illegal to sell vermiculite if it contained any trace of asbestos
I dont know about the states though.

I think that vermiculite board is so rare in the US and why nobody wants to produce it domestically,  is due to a  reputation / public perception issue that is still having a ripple effects throughout the construction materials market.
This is  because of its historical association with asbestos in the USA .
Which is a bit strange as I am led to believe that you can buy bulk vermiculite granules in almost every garden supply stores in all the states for horticultural use?
However if you find vermiculite used as an insulation product, in any properties built during the 1900s the EPA is still telling people to assume it contains asbestos!
A mine near Libby, Montana, was the source of over 70 percent of all vermiculite sold in the United States from 1919 to 1990. There was also a deposit of asbestos at that mine, so much of the vermiculite from Libby ‘was’ contaminated with asbestos.
During those years vermiculite from the Libby mine was used in the majority of vermiculite insulation in the United States and was  sold under the brand name. ZONOLITE
But, nobody batts an eye about growing food in vermiculite granules, potting indoor plants, or using it for animal feed additive.. because vermiculite from most other mines is completely safe, to the best of my knowledge, none of the vermiculite currently being sold contains any asbestos.

Its is a shame as it really is a very useful product!

My local Menards sells it in large bags  as insulation for block walls.
I don't know how effective it would actually be in that application.
Around here large bags of perlite are harder to come by, usually only available during the springtime at nurseries.

We bought a pallet of coarse vermiculate from Uline when building Square Foot Garden beds. It was the most economical option we could find for the quantity we wanted -- https://www.uline.com/BL_3801/Vermiculite

When i started looking for CFB and other similar products , found this site /manufacturer in south africa of a whole range materials ---site has lots of info on as well ---KERAMICALIA--- if you look at the Binders page ---it gives a whole range of what they use ---of course no recipes ,methods or formulas ---they are a commercial enterprise --but at least some more info.

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