Varnish, Aqueous and UV: Three Ways to Protect a Printed Sheet

A printed sheet leaves the press with wet ink on it. Ink that rubs off on a hand, a bag or the next sheet in the stack is a problem, so most commercial work gets a clear coating before it is folded or cut. Three coatings do that job, and they are not interchangeable.

Varnish

Varnish is a clear ink with no pigment in it. It runs through a normal printing unit using a plate, so it can be laid down in a precise spot, around small type or a single logo, while the rest of the sheet stays bare. It dries by absorption and oxidation, slower than the other two, so sheets may need to sit before folding. Oil based varnish can yellow over time on white paper. Of the three it gives the least protection against scuffing and moisture, and it is the cheapest.

Aqueous coating

Aqueous coating is water based and goes on in a dedicated coating unit right after the last printing unit. Hot air or infrared lamps dry it fast, so sheets can be folded and trimmed almost straight off the press. It stays clear instead of yellowing, takes gloss, satin, matte and soft touch finishes, and recycles easily. It needs a heavier stock, usually around 80 lb text or more, because lighter paper curls from the water. It is the standard coating on brochures, mailers, folders and book covers.

UV coating

UV coating is a polymer resin cured instantly by ultraviolet light. It gives the hardest surface of the three and the glossiest look, deep blacks with strong contrast. Because the cured film is rigid, it cracks along a fold if the stock was not creased first, and it is harder for paper mills to de-ink. Spot UV over a matte background is a common way to make one element stand out.

How to choose

Varnish suits short life, low budget work and fine spot details. Aqueous suits general commercial jobs that need fast turnaround and recyclable protection. UV suits heavy use and premium pieces where the shiny finish is part of the design. Whichever is chosen, any sheet that will be folded under a rigid coating should be creased beforehand.

A coating is invisible on the finished piece until something goes wrong with it. When a printed cover scuffs in a bag, which layer do you think failed?