Blot, Don’t Rub: "Remember not to rub the stain, as this can push the ink further into the fabric fibers," Arias-Spinelli instructs. Instead, blot the stain gently until the ink begins to lift.

Australian scientists have created ink that can remember vast amounts of information. The memory ink can be printed on to surfaces by an inkjet printer. It may look transparent to the naked eye ...

Graphene-based inks are transparent, too, incidentally -- by virtue of being incredibly thin, and because of graphene's regular, honeycomb arrangement (see above).

An inkjet—the type of color printer most have at home—creates full-color images by shooting microscopic droplets of ink, in different sizes and colors, onto a piece of paper.