Method for reducing invalid acceptances of expired printed offers and end- consumer re-distribution of printed works

摘要

There is disclosed a method for the time-delayed defacement of all or part of a printed work, such as a time-dependent coupon. Such method comprises applying opaque print onto a substrate and applying an opacity- labile composition of lesser nascent opacity than the visible print onto the substrate in such a manner that a change in the opacity of the opacity-labile composition causes a time-delayed defacement of the printed substrate.