Why use varnish and coatings?
Varnish and coatings are used for a myriad of purposes. Some are from a production standpoint and others are to enhance design.
One of the simplest reasons to use a coating is when printing short runs either work and turn or work and tumble. Aqueous coating allows us to print the second side immediately.
The aqueous coating seals the ink and the coating dries quickly.
Creating Visual Effects
With a broad range of coatings and varnishes with different finishes, tints and textures available that can be used to flood the entire piece or in specific areas, designers can use these elements to create visual effects on their printed pieces. Varnishes and coatings provide designers with an ability that online media can not – give tangible depth, dimension and texture to images and words.
Coatings can provide protection from moisture, scuffing, scratching or fingerprints to keep a project looking professional.
What’s the difference between coating and varnish?
Coatings come in three types: aqueous, UV and Soft Touch®
Aqueous coatings are among the most commonly used coatings. They provide better rub protection than varnish and increase durability of the printed piece. These low-cost, clear, water-based vegetable cellulose coatings are applied to the sheet after the ink. Sheets with aqueous coating can be handled almost immediately.
Because they consist of 60-70% water, aqueous coatings are generally offered as a flood coating, covering the entire sheet. The water content of these coatings also effects which stock you use. Uncoated stock is very porous and acts like a sponge when the coating is applied. It is recommended that aqueous coating be used only on coated stock because it has a surface sealant that allows the coating to sit on top of the sheet rather than be adsorbed into the fibers. The water content of aqueous coating also requires a thicker stock (60# text and up) to avoid paper curl when wet.
UV is a type of coating that is cured by exposure to ultraviolet light to dry instantly. UV coatings can be applied as a flood coating or as a spot coating and provide an exceptional gloss level. UV coating is more protective than aqueous, but can crack when scored or folded. If you plan to have a project folded using UV coating, a specialty UV coating may be used to reduce cracking (known as 4875 PKY). Because of how slick it is, UV coating is not recommended on areas that will be hand-written.
Soft Touch® coating is a flood coating that, when applied, creates a velvety texture. As its name implies, the coating creates a soft look and feel while creating a fingerprint-resistant barrier. This fast-drying coating is non-yellowing and eco-friendly, but will cause a slight shift in color. Soft Touch® coating is not advised for intensely color-critical pieces.
Varnish is essentially ink without pigment and is available in many finishes including gloss, satin and dull. When applied in-line using a regular ink unit in the press, varnish can achieve exact dot-for-dot registration. Varnish manipulates how light reflects or is adsorbed into a sheet. Gloss varnish deepens colors while satin and dull finishes reduce contrast between colors.
Different methods can be used in applying varnish to achieve different results. Wet trapping is when varnish is laid in-line on top of wet ink. This method achieves the best registration. The opposite method, dry trapping, is when the ink is allowed to dry prior to putting it through the press a second time to print the varnish. Dry trapping results in more contrast and a glossier look, but takes longer and requires two passes through the press. Strike-through varnish is a technique in which a dull or matte varnish is applied on all areas of a coated sheet except for the areas that are intended to be glossy. Then, a high-gloss aqueous coating is flooded over the sheet. As it cures, the varnish strikes through the aqueous coating to achieve a dull finish where varnish was applied and the areas where the varnish was not applied appears glossy. This process is more cost-effect than a dry-trap varnish, but it does not achieve the same contrast.
Varnish offers much opportunity with its ability to be tinted, flooded or used as a spot and applied using different methods, but does have a few drawbacks. Varnish offers a relatively low degree of protection compared to other coatings, tend to yellow over time and have longer drying time.
Want to see samples?
Contact your Printing Partners sales rep for samples of different types of coatings.