Printed security with hallmarks

摘要

This invention relates to a security paper with a hallmark in the form of a coating applied by vacuum deposition techniques to the surface of a paper substrate. The coating is very thin and almost invisible to the naked eye even as a metal layer, although permitting accurate automatic or machine examination for verification purposes. the absorption of the hallmarks in a certain range of the wavelength of the spectrum, the exiting spcetrum of luminescence, the photoconductivity and/or the electrical conductivity of the hallmarks are characteristics used during the automatic examination of the authenticity of the security paper.