I help DH teach a lab at school (8th grade) dealing with the chemistry of fiber reactive dye. As part of the lesson, we dye shirts. I know...it's a sly way to goof off at school.

In a nutshell though, the soda ash changes the composition of the fiber, to leave an available "slot" for the dye molecule to slide in there. Rinse the soda ash away after the process, and the pH returns to normal, the dye is permanent.

So....biggies to ensure good dyeing: follow the directions. If you're trying to dye 5# of fabric with 1# worth of dye, you're not going to get a very deep color. There's just not enough dye molecules available, kwim? Soda ash...there's a range that's acceptable, but again too much or too little will not result in the correct pH. Finally, think of water as the vehicle for the dye to reach the fiber. Too little water (as in, not covered for LWI and dries out) only lets the dye hang out on the surface, and not complete the reaction. Too much water (in LWI, the dye molecules drip off into your pan-bag-whatever) and you've just wasted the dye.

Dyes like "RIT" merely stain the fabric, and will ultimately fade. With fiber reactive, there may be "extra" dye that rinses out the first wash or two, but after that...it's in there!

Thanks, Rebecca, for the explanation.

Sounds like those school kids get the best! How I would have loved to do this instead of... Well, I went through a looooooong time ago. No fun projects. Just the basics. :roll:

Thank you all for the information. I will read up and give it a shot. Is it worth doing money wise? I just cant seem to justify spending $15.00 dollars a yard if I can do it cheaper myself and get close to the same results.