FIELD: physics.
SUBSTANCE: invention relates to protective devices for marking valuable documents. Method of making a security feature for protecting a valuable document, wherein said security feature exhibits a blue colour when viewed in transmitted light and a metallic yellow colour when viewed in an incident colour. Manufacturing method includes the following stages: a) printing a specific UV-curable ink on a transparent or partially transparent region of the substrate of the valuable document; b) heating the paint layer obtained at step a), at temperature from approximately 55 °C to approximately 100 °C for at least one second so that the paint layer exhibits a metallic yellow colour when viewed in an incident colour; and c) curing under the influence of radiation in UV and visible region of the ink layer obtained in step b), to form a security feature. Method of manufacturing according to the present invention enables to expediently obtain protective features exhibiting a blue colour when viewed in transmitted light and metallic yellow when viewed in incident colour and is especially useful for industrial printing of valuable documents.
EFFECT: high security of valuable documents from forgery and/or illegal reproduction.
24 cl, 17 tbl
