Abstract: A method of heat-treating multilayer interference platelets to improve the durability of the platelets comprising subjecting the platelets at a temperature of 200.degree.-300.degree. C. for 10 minutes to 24 hours. The platelets are formed from a multilayer interference thin film construction comprising a metal reflecting layer having a multilayer interference thin film structure on both sides of the metal reflecting layer wherein the multilayer interference thin film structure comprises a pair of layers consisting of a dielectric layer and a semi-opaque metal layer with the dielectric layer of the pair being directly adjacent to the metal reflecting layer.

Abstract: A color-shifting paint comprising a polymeric paint medium and a plurality of colored interference thin film platelets dispersed in the paint medium. Each platelet being characterized in that platelets has first and second generally planar outer surfaces and an edge thickness perpendicular to the first and second generally planar outer surfaces. Each platelet is comprised of a metal reflecting layer having first and second surfaces. A multilayer interference structure is disposed on each of the first and second surfaces of the metal reflecting layer to provide a symmetrical platelet. The multilayer interference thin film structure comprises a pair of layer consisting of a dielectric layer formed of a dielectric material and a semi-opaque layer. with the dielectric layer directly adjacent to the metal reflecting layer. The thickness of the dielectric layer determines the color and the dielectric material determines the degree of color shift.

Abstract: A collection of color-shifting interference thin film platelets of high chroma characterized in that the platelets are comprised of a metal reflecting layer having first and second surfaces and a multilayer interference thin film structure disposed on both surfaces of the metal reflecting layer. The multilayer interference thin film structure comprises a pair of layers consisting of a dielectric layer and a semi-opaque metal layer with the dielectric layer being directly adjacent to a surface of the metal reflecting layer. The layers of the multilayer interference thin film structure lie in parallel planes. Each platelet has an aspect ratio of at least 2:1, respectively, for surfaces parallel to the planes of layers and surfaces perpendicular to the planes of the layers. The platelets have a maximum dimension on any surface ranging from approximately 2-200 microns.