jbjints-
It's actually RIT dye and you can get it in liquid form as well. A little more easily dissolved in water.
You can also dye any lighter color, not just white. But the color you're dying must typically be darker (blue, purple, black, red). I've done yellow, orange and flo. green wheels to various darker colors.
You can adjusty the depth and tone by the length of time you let the parts soak. I made some yellow rims a flo. orange with red dye using a weak mixture and shortened the soaking time.
Enjoy.
-SlingItX