Bleed in Blue

Artist inks do work, just look for the ones that say water proof and that sort. You can mix 'em with rubbing alcohol to make more of it or lessen the intensity of the color. You can also squeeze the ink out of sharpies (after cutting away the plastic part) but it makes a huge mess for a pitiful amount of ink, so the bottles artists ink work best. The ones I used to a good deal of success were Koh-i-nor mixed media and india inks.