ng concealed information, photoerasable paint for temporary markings on terrain and structures such as signs, roadways, trees, and buildings,...http://www.google.es/patents/US6120949?utm_source=gb-gplus-sharePatente US6120949 - A temporary markings comprising a colorant, a mutable colorant and an ultraviolet radiation transorber, when irradiating with ultraviolet radiation, and changing the colora