I've been playing around with food coloring for dying wool sweaters. I discovered that if it's fairly concentrated, you can make the colors quite bold and blending - it looks like tie dye - or just plain rainbows
I'm so excited about the possibilities with this
Here's the link to my tutorial
http://manyskiesmama.blogspot.com/2010/10/tutorial-id-like-some-rainbows-on-my.html