transmitted light application_number US 52925090 A description a u s currency bill 10 of the type described in u s pat nos 4 652 015 and 4 761 205 which patents are incorporated herein for purposes of reference is depicted in fig1 the currency bill consists of a security thread 12 incorporated within the currency paper 9 which includes printed indicia as generally indicated at 11 to depict a united states president as well as the bill denomination the end of the bill 10a containing the security thread 12 is depicted in fig2 to show the cross sectional placement of the security thread 12 relative to the width in the currency paper the security thread comprises a polyester film 13 of polyethylene terephthalate which is coated with a pigmented resin 14 that is readily soluble in ethyl alcohol and hereafter referred to as 34 soluble pigmented resin 34 the pigment is selected to match the color of the currency paper the soluble pigmented resin is next coated with a thin continuous film of aluminum metal 15 applied by a vacuum deposition process for ideal opacity the aluminum layer should be in excess of 300 angstroms in thickness next a layer of pigmented resin 16 that is insoluble in ethyl alcohol hereafter 34 insoluble pigmented resin 34 is printed over the aluminum the insoluble pigmented resin has the same color and.