Vermiculite in America

[fox]

I have been lead to believe that vermiculite granules and especially vermiculite board is very hard to come by in the States?
I only ask because I have some American friends on a rocket stove forum, who say it is simply not available at all?
Do we have any American folk on the forum who have managed to find any in the States?

[UtahBeehiver]

I did a quick Google and vermiculite granules seem readily available in the US (have them check Zonolite brand). Board seemed to be a little more harder to find but many fireplace stores carried them. Can they use CaSI or AlSi board which is more readily available?

[fox]

Thanks, apparently casi and aisi are not good in the flame path.
Where I live vermiculite is very common and virtually every modern wood burner stove is lined with it but it seems not in American!

[david s]

I've read both vermiculite and perlite are good for 1000C. My own tests firing samples of both in my kiln up to 1130C show both turn to dust. Quite ok for a wood fired oven service temperature though.

[fox]

The vermiculite board that I use is rated for 1150c and has happily survived 750- 800 c for over 100 fires so far ….
That is why my American friends want to use it but the board is simply not available to them!

It would appear that there has been some improvements in recent years as l also previously found the board to be unreliable and short lived.
Also new products like Zircon Refractory Paint Coating can take 1800c and works well with vermiculite.

As it has become apparent just how dangerous ceramic fibre product can be when super heated, many folk are being scared away and seeking safer alternatives!

I guess it wont be long before some enterprising person starts importing the board.

[david s]

Are you sure you have your temperatures correct? I think you may have C mixed up with F.
A wood fired oven won’t reach 800C. The bricks at that temperature would be glowing a dull orange. With an open door the large air intake holds the temperature back to a max of around 450C
Regarding ceramic fibre blanket, hot face fibre is commonly used in kilns and furnaces operating to service temps exceeding 1300C without failures. The earlier generation of ceramic fibre is classified as a class2 carcinogen, which mean’s tumours found in lab rats, but none reported in humans. The latest generation of ceramic fibre is exonerated as a carcinogen due to its different manufacture resulting in a larger fibre, not problematic to inhale as well as being biosoluble. More expensive, but safer.
Recently I’ve noticed a huge increase around 50% more, in the price of vermiculite over that of perlite.The reason no doubt being the higher temperature, 1000C as opposed to 540C of exfoliation and the associated increased energy costs.They used to be roughly the same, now vermiculite 50% dearer. Thanks Putin.

[fox]

Hi David I am not confused about anything!
My opening post clearly states we are taking about my friends on a rocket Stove forum who can not find vermiculite in the States.
Our rocket stoves can operate at well over 1000c but my small 4” model is more happy around 800c.
Ceramic fibre may well be safe to use with sensible precautions but even the body soluble versions, once super heated, are not safe as the fibres take on a new form that are no longer body soluble!
So as long as you are wearing a mask and the fibres are then enclosed, then yes reasonably safe to use but once exposed to high heat the fibres are no longer safe to handle or inhale!

Ceramic fibers used as a hot face will start to crystallise at around 800c but are completely transformed by 1200c.
This is a fact that is well documented but not mentioned by most of the manufactures.
There is some scientific Evidence and links in this thread…. https://donkey32.proboards.com/threa...e-board?page=2

[david s]

My apologies, I wasn’t aware you were talking about rocket stoves. I assumed you were talking about ovens.
Yes, I would be interested in a link. Many potters coat thei inside of their fibre ovens with rigidizer which seals and strengthens the surface.

[fox]

I have added a link, yes that is the way but Zircon is the latest stuff….

[fox]

Just for interest … a basic 6” batch box rocket stove will operate at over 1200c … That is seriously hot for a none air forced wood fire.
I built a 6” vortex stove but it was far to powerful for my use so I scaled down to a 4” I dont know what the air temps can get to but the face temp in the afterburner are around 7-800c.and that takes around 10 minutes to get there!

[david s]

Hi David I am not confused about anything!
My opening post clearly states we are taking about my friends on a rocket Stove forum who can not find vermiculite in the States.
Our rocket stoves can operate at well over 1000c but my small 4” model is more happy around 800c.
Ceramic fibre may well be safe to use with sensible precautions but even the body soluble versions, once super heated, are not safe as the fibres take on a new form that are no longer body soluble!
So as long as you are wearing a mask and the fibres are then enclosed, then yes reasonably safe to use but once exposed to high heat the fibres are no longer safe to handle or inhale!

Ceramic fibers used as a hot face will start to crystallise at around 800c but are completely transformed by 1200c.
This is a fact that is well documented but not mentioned by most of the manufactures.
There is some scientific Evidence and links in this thread…. https://donkey32.proboards.com/threa...e-board?page=2

Those links are far from conclusive, most are posters opinions. As the ceramic fibre blanket is enclosed in a wood fired oven and the temperatures it is exposed to are well below any of the chemical changes in contention, builders have no concerns of those possible dangers.

[fox]

Well we are being side tracked, there is little danger with its use in a pizza oven but my point was .. my friends in America are looking for vermiculite because they no longer wish to use ceramic fibre in places that exceed 800c.
The evidence is quite accurate and complete in that ceramic fibre changes its chemistry once exposed to high heat.
Whether or not anyone wishes to expose themselves to non soluble fibre is obviously their own choice

[w650gb500]

I used Perlite granules in my WFO and had no issues finding it. Check a masonry supply or fireplace store. We bought it locally(northeast PA), but I believe it was also available to purchase online but shipping was an issue.