It was the Vermiculite Insulation that was the dangerous substance.  If your bag of vermiculite was intended for use as insulation I would not use it.  If the vermiculite is the stuff sold in garden centers today, it should be fine. 

Here is a thread that discusses this in more detail.

Ground Goop - Who uses it?

Blue,

Thanks for that information.  Now, I need to take a look at the bags and see just what I have. I may have to take it to a hazmat disposal site.

IF it is useful, how was it mixed into the plaster (ratio)?

If that bag is vermiculite from the Libby Mine, don't mess with it.  The airborne dust is a killer!

IF it is useful, how was it mixed into the plaster (ratio)?

What I know about using vermiculite with plaster for ground goop I learned from Joe Fugate's Scenery DVD's.  The segment on mixing and using ground goop, (Tenmile Creek Series Part 4: From the Ground up, Basic Terrain) can be downloaded from the Model-Trains-Video website for $1.99 or less, depending on the video quality selected.  I recommend the 2 DVD scenery set as a must have for the mixes and techniques provided within.

If I remember correctly it's just plaster, vermiculite and a pigment to counteract the stark white plaster color.

I use fine vermiculite.. the kind you might use for potting plants.I suspect a powder would not work as well to give texture.

I use a 50/50 mixture of vermiculite and plaster. I tint it with paint tint. Joe's video is highly recommended (it has pictures of the kind of vermiculite to use if I remember..) and he has a formulation using portland cement. I didnt want to use cement.. so I omit that and use paint tint ala Dave Frary (whose book is another good source although not for this particular goop technique).

Vermiculite is amazingly light.. so if you do have to order some it does not cost as much to ship as you might fear.

Chris

Joe has since stopped using portland cement, which he added for color.  He uses paint pigment now as well, because of the tendency for shrinkage cracks with the portland cement in the mix.

The Vermiculite sold in gardens shops is Basically Volcanic encased Mica & Nitrogen that has been mixed and Heated to expand then crushed into a usable soil additive to help loosen Heavy soils.

Joe used it to mix with Portland cement which Portland Cement is what is known as swimming pool concrete and is designed to be a flexible non cracking cement. When you add any Mica product to cement it dries the cement too fast causing both shrinkage and swelling at the same time removing the elasticity of the Portland cement. That's why Joe had the cracking problems.

Used with plaster and stucco it speeds up drying and makes for good scenic effects as Joe explains in his Scenery Video.

The insulation type Vermiculite was mixed with asbestos and Volcanic Rock dust and is no longer sold in the U.S. because it has been considered a major cause of lung cancer.

Dan

I use 1 part vermiculite and 1 part US Gypsum No. 1 Casting Plaster with some tempera powder mixed in the kill the stark white color.  Lowe's carries garden vermiculite and that's what I've been using.

A 1/4" thick shell of this mix is stiff and very sturdy, can be poked for small holes and drilled for larger ones.

I mix up a 16oz cup of vermiculite, a 16oz cup of plaster (paper, throwaway cups), a table spoon or so of tempera powder. I add these components to flexible plastic bowl that has about 14oz of water in it (experiment to find out how much water is needed).  I sprinkle the plaster onto the water first, then the vermiculite, then the pigment powder. I let it sit for about 30 seconds, then mix it all together with an old metal egg whisk (mixes well, easy to clean).

When working with this stuff I keep a 5 gal bucket in the deep sink and do all my tool/bowl cleaning in that bucket. I don't want plaster residue going down the drain as I'm not keen on finding out what roto-rooter charges for houise calls.

I get just enough working time out of a batch of the stuff to spread it on a cardboard mesh with tape substructure, run and clean the bowl and scraper, then run back and finish smoothing out the plaster/vermiculite mix.

Go back and finish cleaning the tools, then it's time for the next batch. I can do (mentally estimating) about 3 batches per houir if I work at it. A batch covers about 1.5 square feet (not 1.5' x 1.5',  1' x 1.5').

It's the easiest way to build a solid free-form scenery sub strata that I've found yet. Carved pink foam has its uses, but if I'm building a 12" high or taller rolling hils with cuts/fills, the plaster mix is easier.  It think (but have no proof) that the plaster is quieter than pink foam scenery (pink foam tends to make a good sounding board in my expeirence - which may of course, be completely wrong).

A 25lb bag of plaster will run around $10. A bag of vermiculite will cost around $7  (prices are by not entirely reliable memory).  A goodly stack of pink foam can get a bit spendy.

I'd say give it a try.  If you can't get No.1 Casting Plaster (try an art supply store) give plaster of paris a try (though it may set up even faster).

Cheers,

Charlie