Overprint varnish (OPV)

oil print varnish

The construction of oil pressure paints equivalent to that of conventional offset inks substantially. It is achieved by this method increased abrasion resistance and expression the gloss. For effective processing of OPV, however, is not enough.

Technical background

Oil-based varnishes are made of hard resins, mineral oils and oxidatively drying oils. In a combination of absorption of the mineral oil fractions and oxidation of the oils the paint dries. The application of the paint takes place in-line in the offset printing machine. This is transmitted over an inking unit to a normal pressure or a special coating plate. This transfers the paint accurate to the substrate. Full-scale and very intricate paintwork and also gridded spot coatings are therefore possible. The drying, due to the oxidation, it takes much longer than the printing time. Especially in the stack should pay attention to good ventilation and some powder. By a suitable radiation, such as Infrared, the curing can be accelerated considerably.

Effect

In different qualities Oil-based varnishes are obtained in matt, semi or semi-gloss, gloss and high-gloss effects. However, the gloss values ​​are not high and thus this method is rarely used in commercial printing.

Application possibilities

There is oil pressure paints in a variety of qualities for effects such as matt, semi or matte, shiny and glossy. The printing of paper and also particularly absorbent varieties is possible. Used as a primer, it can be readily printed later. In the bookbinding finishing he ensured through the thin elastic layer and a good scoring, folding and embossing. Since oil pressure paints were changed in their composition, they are now yellowing and can be used for full-surface varnishing.

Limitations

OPV can not be applied to plastic-or metal-coated materials. The maximum transferable layer thickness is 1.5 g/m².

Costs

The similarity compared to offset printing inks is also evident in the cost. The costs can be compared with the offset printing process, because the oil-based varnish as conventional ink is applied.

Sources and additional literature

[1] Kipphan, Helmut: Handbuch der Printmedien – Technologien und Produktionsverfahren; Springer-Verlag Berlin Heidelberg, 2000, Seite 147

[2] Kleeberg, Dieter: Inline-Druckveredelung mit Lack. KBA Process Nr. 4, Ausgabe 1/2007

[3] Hille, Frauke Helene: Veredlungsmöglichkeiten und Spezialeffekte für Bücher und Broschuren; Diplomarbeit, Hochschule für Technik, Wirtschaft und Kultur Leipzig (FH), Fachbereich Medien, Studiengang Verlagsherstellung, 2008

[4] Beckmann, Till; Morlok, Franziska: Extra: Enzyklopädie der experimentellen Druckveredelung; Birkhäuser Verlag, 2009

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