METHOD OF MAKING TICKETS OR OTHER VALUABLE DOCUMENTS FOR PREVENTING OR RENDERING DIFFICULT THEIR IMPROPER UTILIZATION

摘要

1520919 Preventing fraud B A LINDSELIUS 15 Dec 1975 51328/75 Heading B6A A ticket or other document of value intended to be stamp-cancelled, bears a filler, e.g. magnesium trisilicate, over at least that area intended to be cancelled, and a stripe or wave pattern, over said area, of crushable microcapsules in a binding agent, the microcapsules containing a colourless colour former, e.g. gelatin. When the stamp is applied the capsules are ruptured and the colour former reacts with the filter to produce an invalidating coloured mark.