Invisible ink is applied to a writing surface with a fountain pen, toothpick or even a finger dipped in the liquid. Once dry, the paper should appear blank or the ink is not an invisible ink. Unless the ink...
Bet this has happened to you! You go to print something and you get a paper jam. Your beast of a machine instructs you to turn it off, remove the jammed paper, turn it on again and proceed to print. NOT AS...