Applications of photoerasable colorant composition include photoerasable price markings for pricing goods, documents such as gaming tickets for securely communicating concealed information, photoerasable paint for temporary markings on terrain and structures such as signs, roadways, trees, and buildings,...http://www.google.fr/patents/US6127073?utm_source=gb-gplus-shareBrevet US6127073 - Method for concealing information and document for securely communicating concealed information
Method for concealing information and document for securely communicating ...
