2 oz bottle of Speedball's high-quality ink. All these inks are acrylic, except for the black, which is India ink.
Did you know? India ink--made from fine soot--is also waterproof, but was fairly new to Europeans in colonial times, and they had not yet figured out how to make it. Instead, they traded for it with India, hence the name "India ink," despite the fact that it was invented in China.