Abstract: According to one aspect of the invention, a printed security device for a document comprises an intaglio printed latent image which has been printed onto a substrate using a highly reflective ink, wherein the intaglio printed latent image is visible when viewed within a first angle range extending from near-vertical to the plane of the latent image towards the image and also within a second angle range closer to the plane of the image, and is not visible when viewed within an angle range between the first and second angle ranges. A change in viewing angle from one angle range to an adjacent angle range results in a visible latent image becoming invisible or vice versa (creating a flip-flop image visibility effect).

Abstract: According to one aspect of the invention, a printed security device for a document comprises an intaglio printed latent image which has been printed onto a substrate using a highly reflective ink, wherein the intaglio printed latent image is visible when viewed within a first angle range extending from near-vertical to the plane of the latent image towards the image and also within a second angle range closer to the plane of the image, and is not visible when viewed within an angle range between the first and second angle ranges. A change in viewing angle from one angle range to an adjacent angle range results in a visible latent image becoming invisible or vice versa (creating a flip-flop image visibility effect).

Abstract: A sheet material, such as a bank note, having tactile indicia therein, the tactility of which is resistant to deterioration and useful for assisting persons with impaired vision to identify one or more predetermined characteristics of the sheet material such as a bank note. The sheet material has therein at least one embossment forming the indicia and comprises a first surface and a second surface, with one of the surfaces defining a cavity in the area of the embossment. A layer of reinforcing material is provided to at least the area of that surface which comprises the cavity. Once the reinforcing material is dried and/or cured the embossment (indicia) is strengthened by the layer of reinforcing material and thereby rendered more durable when the bank note is subjected to the wear of circulation. The reinforcing material may be selected from the group consisting of varnishes, inks, adhesives and caulking compounds.

Abstract: A two-part metallic ink composition for intaglio printing is provided which produces bright and shiny ink deposits when printed. The two parts of the ink are stored separately from each other and mixed together either immediately or within a predetermined time period prior to use. The first part comprises varnish in the amount of 60-85%, wax in the amount of 6-15% and solvent in the amount of 6-25%, by weight. These three constituents of the first part are heated together until the wax has just completely melted, stirred and cooled to room temperature. The resultant mixture, which appears physically as a gelled varnish (vehicle), advantageously permits the formulation of a bright metallic intaglio ink without the use of an extender. The second part comprises metallic pigment. About 1 part by weight of the first part and about 0.5-2.0 parts by weight of the second part are mixed together to form the composition.