This is what I was talking about in class today
It's called thin layer chromatography and it basically separates things into individual compounds, so for black ink it separates it into the blues and greens and reds and yellows and what not. And the patterns can look kind of cool. It tells you how to make a plate to do it on, but maybe you could translate it to fabric. I know when I did it as a kid we just used paper towels dipped in water, so I'm sure you could figure out how to use fabric.