I'm slowly making progress on my denim purse. I decided to make the lining from an old futon cover. It's a nice cotton, but the blues in it were awfully dull, compared to what I've painted on the outside. So, I decided to overdye it with blue pigment dye.
Pigment dye is a lot of fun, and very easy to use. It comes in liquid form, and you just add water to dilute it to the color you want. It doesn't dry as a solid color -- the dye sort of pools in places, and so some spots are colored more deeply than others. I enjoy the mystery of "what's it going to look like when it's dry?" A big advantage of pigment dye is that it works on lots of different fabrics, including cotton, polyester, rayon, and nylon. I get mine at Dharma Trading (www.dharmatrading.com), a great resource for all kinds of dyes, paints, clothing blanks, and books about dyeing.