Printing varnish on the surface of printed self-adhesive materials is a relatively common post-print finishing process for self-adhesive label production. According to incomplete statistics, about 50% of the current wet glue and self-adhesive labels will use the varnishing process.

Varnish printed on the surface of self-adhesive labels can not only protect the printed ink surface and increase the brightness of the label surface, but also enhance the waterproof performance of the label, thus playing a good moisture-proof effect. In addition, some varnishes with special effects, such as printable varnish, matte varnish and scented varnish, can also make the label have more functional properties.

Types of varnish and application fields

At present, there are various types of varnishes available in the market, if divided from the drying method, it can be divided into two categories: water-based varnishes and UV varnishes, among which, water-based varnishes are mostly dried by hot air, while UV varnishes are mainly dried by UV light curing. High friction resistant varnish, waterproof varnish, anti-slip varnish, reverse varnish, fragrance varnish, anti-static varnish, tactile varnish and food packaging varnish. Here, I mainly introduce several common varnish application effects from the perspective of usage.

01 Universal Varnish

Self-adhesive labels are made of a combination of face material, glue and backing paper, and the expansion rate of the face material and the backing paper of the label will be different when they absorb or lose water, therefore, the self-adhesive label will be curled after absorbing or losing water because of the difference in the expansion length of the face material and the backing paper. The main function of general-purpose varnish is to increase the gloss and brightness of printed products, but also has a certain waterproof effect, printing varnish on the surface of self-adhesive labels can prevent the label from curling due to the influence of environmental humidity.

02 Matte Oil

The biggest difference between ordinary matte oil and glossy oil is that: after the matte oil, the surface of the printed material will show a matte frosted effect. This effect is especially suitable for some special design effects, such as some wine, cosmetics labels, in order to highlight the design pattern of the product grade design matte effect, and this effect is often achieved in the printing process is through the matte oil. In addition, matte oil also has a certain waterproof effect.

03 Printable varnish

Ordinary varnish is not suitable for printing on such a varnish surface because it contains silicone oil additives and the surface is relatively smooth, and the printed information is easy to fall off. However, in the actual application process, many labels need to print information on the varnish surface, such as food labels, pharmaceutical labels, etc. need to print the production date, batch number and other information on the varnish surface. Printable varnish can be printed on the surface of the material after printing variable information on its surface, this is because printable varnish can form a high surface energy varnish layer on the surface of the material suitable for printing, so that the printed information can be firmly attached to the label surface.