engleski

New methods of varnishing and their influence on optical properties of cardboard packaging

In the process of UV varnishing a thin transparent layer is formed on prints, the gloss of which is considerably higher than that of the originally printed ink. The influence of the thin layer of UV varnish on gloss and on the chromatic values of the basic tonal areas is presented in this work. How the different methods of UV varnishing can influence the change of the colour of cardboard packaging originally printed in the offset printing technique is discussed. The layer of UV varnish is crucial for the reproduction quality. The investigation results show that the considerable gloss increase positively influences the increase of the reproduction quality (gamut), while too high gloss makes good tone visualization impossible. On prints with UV Inkjet mat varnish the gamut of reproduction decreases, while on the prints treated with the UV Inkjet gloss varnish the gamut slightly increases. Offset in-line varnishing (with the flexo unit) gives the greatest gamut and consequently the greatest color reproduction. The measured value of the print gloss does not follow the chromatic values. Achromatic tones (black and printing substrate) have greatest color changes.

UV Ink Jet varnishing; UV offset varnishing; print gloss; CIE LAB ΔE00

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