> Professional Grade: Basics of Printing Coatings
Basics of Printing Coatings
Learn how these different embelishment treatments can impact your printed piece campaign's overall look, appeal, and success.
BY FOLDERPRINTERS WRITERS
July 27, 2023
Automotive body paint, nail polish, furniture and cabinetry. These are some of the prominent types of items that are made more visually appealing, and to some degree protected, by coatings.
What may not be as widely known is that the same practice and principles apply to paper and the printing industry.
In this article, we’ll list the different types of coating and discuss their appropriate application and overall impact on a printing project.
The coating referred to in this piece is that which is applied as an embelishment during print production, which is completely different from the type that is a treatment during manufacture meant to give paper stock its differentiating characteristics in terms of gloss, weight, and smoothness.
Additionally, this distinction is helpful in understanding the type of paper to which printing-process coating can be applied.
The manufacturing type coats papers with materials or polymers that blankets its entire surface giving it — depending on the specified type — either a glossy or matte finish.
Accordingly, this type of paper is therefore professionally categorized as coated, whereas those that are not treated are called, commonsensically, uncoated.
Paper mill coating makes coated paper much less porous compared to uncoated paper. For this reason coated paper is the only type to which printing-process coating can be applied, since uncoated paper will just absorb liquid chemicals thereby negating any of the intended effects.
On the other hand, printing coating is a thin layer of liquid chemical applied over the surface of printed paper. It is done either in-line as the paper is going through press, or post-press which is a separate process performed after initial printing.
Its main purpose is to create creative effects that will enhance and elevate the aesthetic and perceived value of printed pieces.
Now that you have the basic concepts of coatings, here, then, are the different types — their characteristics, function, and appeal.
One sheet of paper cut up and treated with different coatings. On the right shows the sheen of UV. Middle sheet is in its ‘natural’ state; untreated. Left has been aqueous coated; notice a small strip at the bottom that is not coated and shows the difference in sheen.
Perhaps one of the earliest and simplest of the printed embellishment types is varnish. In simple terms, varnish is ink without the pigment, thereby making it colorless, transparent, and smooth.
It can be applied to flood the paper, which means that the entire surface is covered, or as a spot treatment, meaning that it covers only a specific area.
The objective of spot coating is to highlight — or create — an image. This visual effect is achieved by the juxtaposition of the opposing sheen of the varnished area against those that are not — gloss coating on matte paper; matte coating on gloss paper.
Logically, pairing the same type of paper and coating finish — that is to say, matte coating on matte paper — will just cancel out the effect.
One drawback of varnish is that it tends to turn any unprinted area of the paper yellowish over time, For this reason, along with the advent of other, more efficient and environmentally friendly coating types, varnish utilization has dropped tremendously.
That it can be applied as a spot effect is one of the few practical reasons for its use.
Of the major types of printing embelishments that are chemical treatments, UV (an abbreviation of ultraviolet) coating produces the most pronounced visible effect.
It also makes the treated paper relatively water resistant.
This is mainly the product of relatively high solids (despite being in liquid form during the print-production process) content of the chemicals.
UV coating is applied as a clear wet compound over the surface of paper which is subsequently dries and hardens after it is immediately exposed to ultraviolet radiation.
The result is a paper surface with a very thin film that is extremely glossy, reflective, and smooth. Compared to other types of coatings, UV is much more visually arresting and attention grabbing.
Like varnish, UV coating can be applied as flood to cover the entire sheet, or as spot which highlights only a specific area.
The difference betweeen the two coatings being the glaring disparity in sheen and reflectiveness.
A couple of factors that may prove dissuasive for using UV is its higher cost relative to the other types of coating; and the fact that, due to the chemicals and machinery used in its application, it is suitable only for thicker, cardstock paper.
It also ink repellent and thus cannot be written on.
As the name implies, aqueous is a fast-drying, water-based coating.
As such, it is the most environmentally friendly among the major coating types. In industry jargon, it is referred to as AQ.
Available in gloss or matte, it produces — depending on the finish applied — either a subtle or more prominent sheen and effect.
Also available is a “pencil receptive” formula which allows for writing on the coated sheet with a pencil or ballpoint pen — even mailing address printing.
Furthermore, unlike varnish, it is non-yellowing.
While AQ is something that is generally requested by and benefits the client, professional printers also find it beneficial, in that it prevents smudging.
During a press run, smudging may occur when freshly printed paper comes into contact with the preceding sheet that has still-wet ink as they pile up after going through the press.
The coating quickly dries, settles and covers the ink thereby eliminating its ability to stain.
All of the aforementioned features and capabilities contribute to the reasons why aqueous is the most cost-effective and commonly used coating today.
One limitation to AQ is that it can only be applied as a flood and not as spot.
Then there is Soft-Touch, a type of coating that has become quite popular lately. True to its name, it does feel soft to the touch. As opposed to the first three types of coatings listed, which are designed to primarily draw attention visually, the great appeal of soft-touch is its tactile quality and elegance.
Visually, it has a “matte mixed with frosted glass” look. It is non-reflective with almost zero sheen. The texture, where its strength as an embellishment lies, feels like running the tip of your fingers through “micro-velvet” or a rose petal. These unique qualities give any soft-touch coated piece a good chance at eliciting intrigue and, more importantly, attention.
Like aqueous coating, soft-touch can only be applied as a flood and not as spot. As for cost, it is up there with UV.
A black presentation folder that has been coated with soft-touch, on top of which metallic foil is stamped.
Notice the visually striking high contrast between the flat, non-reflective black area (soft-touch coated) against the silver foil's shimmer.
As a leading national manufacturer of custom presentation folders
, we have seen all of these coating types employed by clients
from a multitude of industries. From interviews with some of them, we have confirmed that the goals are indeed to stand out from the competition, get the attention of customers, and to project an image and deiver the message more effectively.
As you can see, different types of coatings have varying features, application, and appeal. With the basic information you now have, you can, depending on your budget and aesthetic objectives, evaluate and determine which, if any, of them could help in making your next printing project and campaign a success.