Covert flakes having one or more symbols and / or a selected shape are used in a composition, such as ink or paint, to provide a covert security feature to an object. In some embodiments the composition includes base
pigment, and the covert flakes are covert
pigment flakes that match the visual characteristics of the base
pigment. In another embodiment, clear covert flakes are mixed in the carrier with base pigment. In another embodiment, clear covert flakes are mixed in a
varnish base to provide a clear composition that can be applied over an existing security feature or elsewhere. The composition is used to print a field on the object, such as a stock
certificate or
bank note, for example. The covert flakes are not readily detectable by causal observation under visible light. In one embodiment, illuminating the covert security feature with
ultraviolet light causes a covert flake to fluoresce and allows the observer to identify the location of the covert flake so that cover indicia may be observed. In a particular embodiment, a covert flake having one or more symbols is located using non-
visible radiation, and then observed under visible light to read the symbol(s) on the covert flake.