Alcohol and sharpies are so much fun. I have played around a bit with this technique. But, I have only used them on postcards. Non-washable items.
Alcohol and sharpies and a spirograph.
Alcohol and sharpies and embroidery
Alcohol and sharpies and applique
These are just small 4 x 6 projects. But, you get different affects depending on the size of sharpie dots or streaks and the amount of alcohol. I've tried small spray bottles and glass eye droppers from Wal-mart to disperse alcohol. I dry thoroughly and heat set after. But, I have never tried washing a quilt square. Should probably do that at some point. I will be watching this thread to see others tips and photos.