Optical Brightening Agent Optical whiteners Completely synthetic substances which refract light and make it appear white to the human eye OCR PAPER Optical Character Recognition Paper, woodfree paper intended for automatic optical scanning OFFSET PAPER Paper intended for use in offset printing Generally has good picking resistance OFFSET PRINTING A lithographic printing method in which the ink is transferred from the printing plate indirectly via a rubber blanket to the paper Both the printing and non-printing parts are at the same level on the plate OPACITY A measure of how much light a paper does not let through