All the dealer/manufacturers of off-line UV coaters I talked with told me that 70-85% of the digital printers they know have UV coaters of some type. My survey, on the other hand, showed only 15% of us have that equipment and provide the service, while another 9% have someone else provide it for them (broker or sublet). So a full 76%, according to my panel, don’t have or provide the service. And that got me thinking…there are a lot of small-format offset and digital printers who don’t know that much about protective coatings. If you do, you’re excused until next month. Everyone else, please pay attention.

The purpose of a coating is to protect the printed piece from dirt, smudges, fingerprints, scratching, etc. Coating also provides scuff resistance. And, yes, it can improve the visual appeal of the piece by providing a glossier and smoother finish.

OK, enough of the Chamber of Commerce pitch: protective coating allows that postcard you did for your top account to arrive looking the way it looked when it was mailed. Printers who are aware that the postal service delivers a licking that keeps on ticking to printed pieces – and use that info to sell against unaware competitors – have an advantage.

Oh yes, the number two use of protective coatings is on business cards, for they are treated badly as well. Coming in third, about five lengths behind, are brochures and other types of sales literature.

Coating Options

The three common types of protective coating are varnish, aqueous coating, and UV coating.

• Varnishes were first in the industry as they are essentially inks without a pigment, or transparent ink. Their advantage is that varnishes are applied on a press, thus you can spot coat as easily as fully coating the sheet. The process is the same as printing spot color. You can also change the varnish from gloss to matte or dull, and thus change the mood of the piece.

The final advantage is that varnish is typically the least expensive of all the coatings available.

Drawbacks: varnish can be slow to dry unless you use a drier and, like ink, it is petroleum-based and could present some environmental issues, but it usually does not create issues in shops of our size.

• Aqueous Coating entered our world in the late 1970s. Aqueous is water-based, and thus does not cause emissions as varnish does. It does what varnishes do, but it’s also a polymer (basically, plastic), so some prefer this type of coating.

A quick dry formula was developed in the 1980s, so there’s no wait before bindery, and it does a couple things more. It reduces the need for powder on the press (I’ll get to the digital part in a minute). It also resists yellowing, which is common with varnished pieces that are stored for a while. Ghosting problems also tend to be eliminated and it complies with environmental laws.

Normally, aqueous is applied to the entire piece (flood) as opposed to spot coating. On the down side, aqueous often costs twice as much as varnish.

• UV Coating is by far the most common small shop application, and has the highest gloss and rub-resistance of all the options. It starts as a clear liquid that is cured (dried) instantly with an ultraviolet light. It comes in a wide range of sheens, although some find it too shiny for some uses.

UV also resists additional imprinting so postcards, for instance, are commonly either addressed before being coated or are coated on one side only so the address may be imprinted on the uncoated side. Similarly, it is common for business cards to be coated one side only so that consumers may write on the backs of them.

Coating Tutorial

Most UV equipment we see would be operated off-line, which provides only a flood coating option. UV gives more protection and sheen than either varnish or aqueous and, since it is cured with light and not heat, no solvents are emitted. You can coat 80-pound text and heavier, although cover weights are preferred. UV can be used on smooth papers only.