I used mostly white cotton muslin. I also had some loosely woven white fabric.
I mixed my own gray using Ultramarine Blue and Cadmium Red Light and Titanium White acrylic paints. That way I can control how cool or warm the gray is. (I learned that in the only college art class I got to take ... Painting 1.) I used various other browns, some yellow, some blues to make the other colors (acrylic paints and textile paints).
I have the gelatin in a cookie sheet (dedicated for this use only) and I made a cover for it by cutting a sheet of plastic I had from something (sorry I can't remember where it originally came from) and then I put duct tape around the sharp edges. The duct tape also acts as a nice seal against the cookie sheet. My gelatin plate is over a month old and has several spots of mold growing on it even though it has been stored in the refrigerator. But the mold spots can be a good thing, and in the case of getting fabric for rocks, it's a very good thing. The spots add a perfect texture that mimics rock textures.
|The gelatin plate with the cover on it|
|The gelatin plate without the cover|
|The plastic cover with the duct tape edges|
|Doesn't look so great at this stage? Just wait...|
|This fabric will be great for rocks|
|I put two fabrics in this frame|
|Can you make out the toilet paper roll shapes?|
|They know how to tug at my heart strings.|