Marking system capable of producing a canceling mark after a predetermined period of time, uses an ink mixture containing a substance which causes a canceling mark to appear over an inscription on the front face of a porous support

摘要

A porous support (1) has an impression (7) on its front face and an inscription (2) on its rear face near to the impression. The inscription, formed by an ink mixture including a pigment and substance with a fusion temperature (Tf1), is invisible from the front side (10) whilst the support is at a temperature below the fusion temperature. The inscription migrates through the porous support so that it can be read from the front side, partially overlapping the impression (7), after a predetermined time period, if the support is brought to a temperature greater than the fusion temperature. An Independent claim is included for a method of fabricating a marking system.