Apply heat to the paper. Use a 100 watt light bulb, an iron or a blow dryer. If the disappearing ink is an acidic or organic substance such as lemon juice or milk, the paper will burn at a different rate than the ink, revealing the spots where the secret ink lies. Advertisement Step...
One day I will find them all having a board meeting in the corner of the clothes dryer.They should have put IR on the iPad. Still mad about that. As far as the patent goes, this is probably one for things already out now but it does cover one of my favorite things about my mac...