Here's what we've learned. Tie-dye is fun, easy, and the results are great. The girls were very happy with their t-shirts and proudly wore them the next day, telling everyone that they've made them themselves.
The kit came with everything we needed: dyes, soda ash, rubber bands and gloves (and a DVD and instructions, of course). I used the regular kitchen gloves, because they stay on better, especially on the small kids' hands. In addition to the kit, you will also need gallon size ziplock bags, one per each item you paint.
The process was not very messy, but it took a long time, and there were a lot of "Are the t-shirts ready?" We made some Jello while the folded shirts were pre-soaking in soda ash solution.
We had t-shirts of different quality, all brand new, the best results were on 95% cotton/5% spandex t-shirts from Target; the worst on 50/50 cotton from Hanes. We also dyed worn, washed, not-so-white-anymore socks, and these turned out great.
We painted 10 t-shirts, two pairs of socks, bandana and a hand towel. And there still was some dye left. The dyes have to be used within 2 weeks of mixing, so if the package says that you can paint 10-15 shirts, make sure to get that many.
Here are some of the t-shirts we made:
b) two-color vertical stripes (stripes are the easiest to make)
c) three-color spiral.
d) three-color horizontal stripes.