The reactions you will get with this prank are awesome… squirt a little Invisible Ink on someone, watch them have a huge reaction, and laugh as the stain completely disappears. Some great acid-base chemistry behind all of the prankster fun. Disappearing ink is a surprisingly very educational product. The perfect introduction for an acid base topic!. Disappearing Ink;100% Satisfaction. We supply you two bottles of 1oz. each of the ink . No instructions . Great Joke or Magic Trick.