Types of vermiculite

[kamelcjo]

I'm starting a new oven and am in process of locating vermiculite I was wondering if there are different types as I have found some that is used for soaking up oil spills would this be good for insulating?

[Lburou]

Re: Types of vermiculite

Vermiculite takes many forms. I used treated vermiculite called Zonolite.

Zonolite Insulation is the trademarked name of a product sold as attic insulation between the 1940s and 1990s. Consisting of the naturally occurring mineral vermiculite, Zonolite was used for decades to insulate millions of American homes.

[Tscarborough]

Re: Types of vermiculite

Zonolite and perlite are the same mineral. What you want is the coarsest available, preferably not silicone treated, but any of them will work just fine.

[david s]

Re: Types of vermiculite

Tom, what is the reason not to use the silicon treated stuff? Because both vermiculite and perlite take up so much water, it's subsequent drying is problematic. I would have thought that the silicon coated stuff will prevent or reduce the water take up and if it were available for me, I'd like to give it a try.
Regarding the grade of the standard stuff, I've tried fine medium and coarse and found the medium grade about best. The fine stuff will take up more water while the coarse stuff does not stick together so well. A mixture of 50% perlite and 50% vermiculite works(sticks together) way better than either alone. Also a handful of powdered clay to every 10 litres (2 gallons) helps make the mix more workable than extra cement. Perlite has way more dust, which is irritating to breathe, than vermiculite.

[Tscarborough]

Re: Types of vermiculite

Siliconization makes it harder to mix, that is all.

[david s]

Re: Types of vermiculite

Siliconization makes it harder to mix, that is all.

"Harder to mix" is that because the grains tend to float? Or do you mean the mix is stiffer?

[Lburou]

Re: Types of vermiculite

I should clarify how I used the zonolite. David S and Tscarborough are real experts, I would heed their views. I used an insulating board under the floor, not zonolite. I used zonolite to insulate over the blanket insulation of the dome because I couldn't find the other vermiculites at a reasonable price locally.