In order to increase the security of value or security documents 100, a multi-luminescent security element 400 is provided which contains at least one first luminescence means 510 and at least one second luminescence means 520. The first luminescence means 510 can be excited under first excitation conditions Sp-1 for the purpose of luminescence, and the second luminescence means 520 can be excited under second excitation conditions Sp-2 for the purpose of luminescence, said second excitation conditions Sp-2 differing from the first excitation conditions Sp-1. The multi-luminescent security element 400 is additionally equipped with at least one absorber means 600 which prevents an excitation of the at least one first luminescence means 510 under the second excitation conditions Sp-2 for the purpose of luminescence.

An optical device is formed by hot stamping a demetallized hologram to an optically variable foil or to a coating of optically variable ink. In another embodiment a hologram is hot stamped to a banknote or document printed with a color-shifting ink.

In order to increase the security of value or security documents 100, a multi-luminescent security element 400 is provided which contains at least one first luminescence means 510 and at least one second luminescence means 520. The first luminescence means 510 can be excited under first excitation conditions Sp-1 for the purpose of luminescence, and the second luminescence means 520 can be excited under second excitation conditions Sp-2 for the purpose of luminescence, said second excitation conditions Sp-2 differing from the first excitation conditions Sp-1. The multi-luminescent security element 400 is additionally equipped with at least one absorber means 600 which prevents an excitation of the at least one first luminescence means 510 under the second excitation conditions Sp-2 for the purpose of luminescence.

In order to increase the security of value or security documents 100, a multi-luminescent security element 400 is provided which contains at least one first luminescence means 510 and at least one second luminescence means 520. The first luminescence means 510 can be excited under first excitation conditions Sp-1 for the purpose of luminescence, and the second luminescence means 520 can be excited under second excitation conditions Sp-2 for the purpose of luminescence, said second excitation conditions Sp-2 differing from the first excitation conditions Sp-1. The multi-luminescent security element 400 is additionally equipped with at least one absorber means 600 which prevents an excitation of the at least one first luminescence means 510 under the second excitation conditions Sp-2 for the purpose of luminescence.

Paper substrates which incorporate covert marking pigments (CMPs) which are one or more infrared (IR) anti-Stokes pigments. Also, processes for incorporating such CMPs into a paper substrate other than by a printing technique, such as, for example, by using a size press or spraying, as well as processes for identifying the presence of such CMPs incorporated into a paper substrate sheet with an infrared (IR) pigment sensor of, for example, a copier or printer for the purpose of adjusting the quantity of printer pigment deposited on a paper substrate sheet or to determine whether the paper substrate sheet is an authentic or counterfeit document.

Paper substrates which incorporate covert marking pigments (CMPs) which are one or more infrared (IR) anti-Stokes pigments. Also, processes for incorporating such CMPs into a paper substrate other than by a printing technique, such as, for example, by using a size press or spraying, as well as processes for identifying the presence of such CMPs incorporated into a paper substrate sheet with an infrared (IR) pigment sensor of, for example, a copier or printer for the purpose of adjusting the quantity of printer pigment deposited on a paper substrate sheet or to determine whether the paper substrate sheet is an authentic or counterfeit document.

A visibly transparent, homogeneous UV-blocking cellulose nanocrystal/lignin nanocomposite film and a method of making the same. The film is made by dispersing cellulose nanocrystals and lignin in an aqueous, alkaline solution to yield a dispersion; casting the dispersion onto a substrate; and evaporating the aqueous, alkaline solution to yield a homogeneous, visibly transparent film that at least partially absorbs ultraviolet (UV) radiation.

A visibly transparent, homogeneous UV-blocking cellulose nanocrystal/lignin nanocomposite film and a method of making the same. The film is made by dispersing cellulose nanocrystals and lignin in an aqueous, alkaline solution to yield a dispersion; casting the dispersion onto a substrate; and evaporating the aqueous, alkaline solution to yield a homogeneous, visibly transparent film that at least partially absorbs ultraviolet (UV) radiation.

A layer-structure includes at least a base layer with a top surface and a top layer, wherein the top layer is arranged above the base layer in a height direction, wherein a first color section is partially provided in and/or on the top surface of the base layer, the first color section and the top surface of the base layer having a luminance contrast, wherein the luminance contrast, defined as Weber contrast, has a value that is at least 0.20, and wherein the first color section and the top surface of the base layer are covered by the top layer, so that a watermark visual appearance is provided.

A layer-structure includes at least a base layer with a top surface and a top layer, wherein the top layer is arranged above the base layer in a height direction, wherein a first color section is partially provided in and/or on the top surface of the base layer, the first color section and the top surface of the base layer having a luminance contrast, wherein the luminance contrast, defined as Weber contrast, has a value that is at least 0.20, and wherein the first color section and the top surface of the base layer are covered by the top layer, so that a watermark visual appearance is provided.