Discharging (removing color) from fabric is probably most commonly done with bleach. Since that's what I had on hand this weekend, that's what I decided to work with first.
I choose some really ugly fabrics from my stash, some commercial prints/solids, and some that I had already overdyed with MX dyes some time in the past.
I just stacked up a few layers, then I got out my plexiglass circles and clamped them tightly. (These plexiglass pieces are available from http://www.etsy.com/shop/r0ssie, by the way)
I stuck this all into a gallon of water with about 1/2 cup of bleach in it. After about 20 minutes, I removed from the bleach/water and stuck in vinegar. Of course, all of this was done in my garage with the door open due to the fumes.
Finished pieces:
This was a funky batik, I like the discharged colors a lot more than the original.
This piece was originally golden yellow, and I had overdyed it with a dark green a while back. The bleach took the dye out, but left too much of the original design in. Definitely a piece destined for the burn pile now.
This was another piece of fabric I tried this with:
After discharging, I over dyed these, one in green and one in blue.
I had wanted to compare the bleach discharge with Rit Color Remover, but it was too cold here this weekend to work outside in my garage. Stay tuned!