I still mix vermiculite into the general terrain plaster because it adds a lightness and softness to the plaster that is handy for terrain.
But for carving rocks, I use Plaster of Paris with retarder added and no vermiculite. I use baking powder - 1/2 teaspoon per cup of plaster is about right. You can experiment to get a setting speed you like - try 1/4 tsp to a full tsp. If you use too much baking powder it will make the plaster foam up and remain soft and powdery when set.
Joe Fugate
Publisher, Model Railroad Hobbyist magazine
(unless you've got it ground superfine) is that you wind up with a nice-looking rock face, then the next day when the light is different, you have all these great hunks of mica reflecting at you. The "great hunks" may be really small, but they sure do reflect!
I avoided Vermiculite after a plant near me, Zonolite, was found to be precessing Vermiculite that contained asbestos. It took a while to clean up the area which is now a rail trail by the former factory. No doubt this must have been an isolated incident.
It supposedly is the worst because of the Tremolite asbestos that exists in that vein of vermiculite. My dad worked at the mine for 25 years, and I grew up with it (unknown to us) The mine has been closed for at least 20 years.
The town of Libby and area has been and EPA Superfund site for at least 15 years.
I wouldn't be too concerned about using it, what you purchase is considered "pure vermiculite". But to each his own.
From Wiki;
Asbestos contamination
Pure vermiculite does not contain asbestos and is non-toxic. Impure vermiculite may contain, apart from asbestos, also minor diopside or remnants of the precursor minerals biotite or phlogopite."Although not all vermiculite contains asbestos, some products were made with vermiculite that contained asbestos until the early 1990s. Vermiculite mines throughout the world are now regularly tested for it and are supposed to sell products that contain no asbestos. The former vermiculite mine in Libby, Montana, did have tremolite asbestos as well as winchite and richterite (both fibrous amphiboles) — in fact, it was formed underground through essentially the same geologic processes as the contaminants. A vermiculite mine in Virginia has also been found to be contaminated by asbestos.[broken citation][4]
-Dean
"The true sign of intelligence is not knowledge but imagination."-Albert Einstein
Vermiculite itself does not contain asbestos; it was just the Libby, Montana mine which was contaminated because of the presence in the mountain of a secondary mineral called diopside.
~Kevin
Appreciating Modeling In All Scales but majoring in HO!
Not everybody likes me, luckily not everybody matters.
Yeah, the Zonolite company in Easthampton, MA use to get that stuff in by rail not far from where I live and contaminated the area around the former plant. Affected a some people who live or use to live here.
I did quite a lot of searching out the product and mines it came from and just did not bother with it anymore.
Vemiculite yes - carving rocks - no
I still mix vermiculite into the general terrain plaster because it adds a lightness and softness to the plaster that is handy for terrain.
But for carving rocks, I use Plaster of Paris with retarder added and no vermiculite. I use baking powder - 1/2 teaspoon per cup of plaster is about right. You can experiment to get a setting speed you like - try 1/4 tsp to a full tsp. If you use too much baking powder it will make the plaster foam up and remain soft and powdery when set.
Joe Fugate
Publisher, Model Railroad Hobbyist magazine
Read my blog
another drawback to vermiculite in rocks
(unless you've got it ground superfine) is that you wind up with a nice-looking rock face, then the next day when the light is different, you have all these great hunks of mica reflecting at you. The "great hunks" may be really small, but they sure do reflect!
But the mixture is nice to work with...
David
another drawback to vermiculite in rocks
The answer to reflecting rocks is paint them before you stain them.
Charlie
Superintendent of nearly everything
Vermiculite
I avoided Vermiculite after a plant near me, Zonolite, was found to be precessing Vermiculite that contained asbestos. It took a while to clean up the area which is now a rail trail by the former factory. No doubt this must have been an isolated incident.
Rich
That is mainly the Libby Montana Vermiculite
It supposedly is the worst because of the Tremolite asbestos that exists in that vein of vermiculite. My dad worked at the mine for 25 years, and I grew up with it (unknown to us) The mine has been closed for at least 20 years.
The town of Libby and area has been and EPA Superfund site for at least 15 years.
I wouldn't be too concerned about using it, what you purchase is considered "pure vermiculite". But to each his own.
From Wiki;
Asbestos contamination
Pure vermiculite does not contain asbestos and is non-toxic. Impure vermiculite may contain, apart from asbestos, also minor diopside or remnants of the precursor minerals biotite or phlogopite."Although not all vermiculite contains asbestos, some products were made with vermiculite that contained asbestos until the early 1990s. Vermiculite mines throughout the world are now regularly tested for it and are supposed to sell products that contain no asbestos. The former vermiculite mine in Libby, Montana, did have tremolite asbestos as well as winchite and richterite (both fibrous amphiboles) — in fact, it was formed underground through essentially the same geologic processes as the contaminants. A vermiculite mine in Virginia has also been found to be contaminated by asbestos.[broken citation][4]
-Dean
"The true sign of intelligence is not knowledge but imagination."-Albert Einstein
http://gearedsteam.blogspot.com/
Vermiculite is safe now
See this MRH forum discussion for more information.
Ground Goop - Who uses it?
Here's a quote from that thread:
~Kevin
Appreciating Modeling In All Scales but majoring in HO!
Not everybody likes me, luckily not everybody matters.
Vermiculite
Yeah, the Zonolite company in Easthampton, MA use to get that stuff in by rail not far from where I live and contaminated the area around the former plant. Affected a some people who live or use to live here.
I did quite a lot of searching out the product and mines it came from and just did not bother with it anymore.
Rich