UV-fluorescent Ink
Ink containing fluorescent substances (pigments) which glows when exposed to UV light (wavelength is usually of 365 nm and 254 nm). The pigments are not visible under normal daylight, only under UV light. The same pigment may have different sensitivity to UV radiation of different spectral ranges. The ink may be used for printing certain graphic elements and general patterns of the banknotes. Security fibers, planchettes, security threads, serial numbers can also fluoresce under UV light (fig. 1).
Fig 1. Fluorescence of the security thread, security fibers, serial number, images invisible under white light in UV light.
500 Nicaraguan Cordobas Oro (2007). Under white light
Fig 1. Fluorescence of the security thread, security fibers, serial number, images invisible under white light in UV light.
500 Nicaraguan Cordobas Oro (2007). Under UV light