METHODS OF CANCELLATION AND COMPOSITIONS THEREFOR

摘要

The invention relates to the cancellation of printed values by use of colour former/colour developer systems. Thus the invention provides ink compositions for conferring a value on an article, the compositions comprising a taggant having a characteristic UV absorption or emission spectrum to indicate said value and a first component of a two component colour former/colour developer system wherein the composition contains sufficient of said first component so that when the second component of said colour former/colour developer system is applied to the first component, the colour developed masks and effectively cancels the value indicated by the taggant. The invention also provides articles coated with the ink compositions and methods of cancelling printed values by use of the compositions.