Transparent linear NIR digital graphics with the intention of security information were printed on a polypropylene material. A label for expensive juices in transparent glass or plastic packaging is demonstrated. Obligatory information about the contents of the liquid was made to be read with the naked eye. The "Z" (near-infrared) information is expanded with data integrated for joint digital printing. This data does not disrupt the original, planned visual appearance of the label, "V" (visible). Although the two graphics are in the same place, the IR graphics on the label cannot be discerned with the naked eye. This brings elements of secrecy and protection against attempts to counterfeit the contents of the transparent packaging. The separation and recognition of the two pieces of information, V and Z, are achieved with a security camera in the near-infrared mode or with one of the many NIR detectors that surround us. In the article, the "VZ" algorithm for the integration of two independent graphics and the limitations set by digital printing are published. Toner properties and the method for developing the recipes for the composition of twin colorants for two spectral ranges are presented using spectroscopy.
Keywords: IR graphics; NIR spectrum; V and Z information; packaging; polypropylene label; security printing.