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fxpose 06-14-2010 07:24 PM

Molding vermicrete
Can vermicrete be applied in globs of layers over several days and molded or carved into shape over the dome? This will be applied over 3" of blanket at the top of the dome so I'm not really after its insulating qualities. What would be a good workable vermiculite to portland ratio for this purpose? Stucco will be applied over this to finish.


gdest 06-15-2010 08:35 AM

Re: Molding vermicrete
Yes you can, go to this site and it will give you all the informtion you need:

fxpose 06-15-2010 09:00 AM

Re: Molding vermicrete
Thanks!! Exactly the info I needed.


Neil2 06-15-2010 03:52 PM

Re: Molding vermicrete
A 12:1 mix will work. If you keep it on the "dry" side it can be moulded quite well.

fxpose 06-23-2010 08:53 PM

Re: Molding vermicrete
I cannot find vermiculite but my local Home Depot sells perlite. Also, a nearby masonry supply house sells perlite as well, and considerably cheaper than Home Depot.
The Home Depot perlite (made by Therm-o-Rock) are pea sized. Is this the right kind to use as I read elsewhere here that I had to use perlite that had already been heat treated and 'popped' to larger sizes? How do you distinguish them or is there any difference? I have not yet seen the perlite from the masonry supplier.


gdest 06-24-2010 05:31 AM

Re: Molding vermicrete
Perlite in its raw form looks a lot like sand. The popped perlite will be white. However I have never seen perlite that is pea sized, this sounds to me more like vermiculite.


fxpose 06-24-2010 07:11 AM

Re: Molding vermicrete
Thanks Gary. These were white and about pea sized. One bag had a small hole in one corner and this is what I saw. Perhaps that was not indicative of what was in the rest of the 2 cu/ft bag. How large or what's the ideal size to look for?


gdest 06-24-2010 08:09 AM

Re: Molding vermicrete

WOW that's going to be a tough one to answer. But let me try. I had a subcontractor run some tests for the perlite I was going use on one of my jobs and here are the results:
US Sieve Size 16 - 10% retained
US Sieve Size 20 - 5-25% retained
US Sieve Size 30 -50 15 -30% retained

Now as I provide that information, basicly perlite (cracked) is not sold by size. Cracked perlite will be VERY light and should look a lot like sugar and have about the same size of regular sugar.
If the bag says perlite I would trust it. However it brings to mind me trying to buy fire clay and everyone who said they sold fire clay actually sold me mortar.


fxpose 06-24-2010 08:53 AM

Re: Molding vermicrete
2 Attachment(s)
I made a quick stop at Home Depot again this morning and kind of poked further into the bag to find that they are actually smaller than pea sized. They basically all looked like tiny broken pieces of styrofoam, light, white, and fluffy. I'm not sure if this is the right stuff to use. I imagined they would be a lot larger in size.

This is what they have:

jota112233 06-24-2010 12:47 PM

Re: Molding vermicrete
Hi George - I've got a pic of vermiculite. This is what it looks like this side of the pond.

This is V4, which is the biggest.



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