Book Printing: Paper Coatings Provide a Buffed Shine

Photo purchased from … www.depositphotos.com

Nothing signals quality like a high-gloss shine, whether it’s a fast car (“I can see myself in your Ferrari”) or even a print book cover.

That said, you have a lot of options if you’re designing a book or any other printed product. The underlying purpose of these coatings separates them into two categories: protection and aesthetics.

Protection vs. Design Aesthetics

Let’s say you’re producing a print book with a cover on which you plan to print a heavy-coverage solid application of ink. Maybe you want to include type, a 4-color photo, and a background of a rich green mix bleeding on all four sides of the front and back book covers and spine. All of this ink, even after it has dried, will be prone to scratching. Your striking cover art could be ruined. This would be a good time to coat the press sheet with a flood application of UV coating, aqueous coating, a laminate, or even varnish—just to provide one more (transparent) layer of protection.

To clearly explain this, I want to take a moment to point out the difference between adding an additional coating, as noted above, and choosing a press sheet that is already coated. These are two separate things. Paper comes to the printer in the following forms: coated and uncoated. Uncoated paper is used for products like the text paper of a print book. Ink seeps into the paper fibers more or less depending on the hardness of the paper surface. In contrast, a coated sheet has been treated to have a far less permeable surface. Ink sits up on the surface of coated paper (this is called “hold-out”), whether gloss (shiny), matte or dull (far less reflective), or even silk or satin (various names for the coating in between gloss and matte or dull).

That said, the kinds of cover coatings noted above for print book covers (aqueous, UV, varnish, laminate) are applied on top of the printed press sheet. Almost always this is a coated press sheet (as described above). Think of this as an open-face sandwich, with the uncoated paper on the bottom, the initial paper surface coating on the next level, then the printed ink, and finally the overall aqueous (or other) coating.

Any time you “paint the sheet” (a printer’s term for laying down a heavy coverage of ink across the surface of the paper), it is prudent to cover everything with an additional coat of something.

Here are your options again with some pros and cons:

1. 1. Varnish is the cheapest option. It is essentially commercial printing ink without pigment. It is clear. In addition, it is applied during the printing process using one of the press ink units. The drawbacks are twofold. Varnish will yellow over time, so it may not be right for printed products you want to keep. Also, it requires an additional ink unit on press, so if you’re already printing 4-color process ink on a 4-color press, that’s a problem. You may need a 6-color press, and this will cost more. That said, if you’re printing black and a PMS color and you want to add a varnish, it will probably be the least expensive option. Varnish can be gloss or dull, depending on the effect you want.

1. 1. UV coating dries (cures) instantly with exposure to UV light. Unlike varnish, it does not need heat to dry. Therefore you can apply a thick, protective, high-gloss coating. However, UV coating is applied offline (not on the printing press, like varnish). It is a post-press operation done in the finishing department. It is therefore more expensive than varnish. Moreover, not every printer has this capability in house. If they have to subcontract the work, this will add to the price and required lead time. But on the positive side, it can make your book cover look like the car pictured above. (It will make the print book cover photo really pop.) On the down side, it can crack when folded, so your printer will need to score the press sheets before UV coating them to minimize this problem. UV coating comes in both a gloss and a dull version.

1. 1. Aqueous coating is water based. It is therefore one of the more environmentally friendly options. Aqueous comes in gloss, dull, and one or more intermediate options like satin (which has an ever-so-slightly rough and textured feel). Aqueous coating can be done on the press (depending on how your printer’s equipment is set up). In this case it is applied to the paper after it has run through all ink units by using an aqueous coating tower just prior to the paper’s exiting the press. Again, not all printers have this capability.

1. A laminate is either applied as a flood coating or as a sheet affixed to the book cover with adhesive and heat. It is thick, transparent, and either gloss or dull in its finish. Laminates (thicker ones) are also used for menus. The goal is to repel water (including moisture in your fingers). This is an off-line process accomplished in the finishing area of the commercial printing plant. It is the most expensive option, and not all printers have this capability. I have found it to be especially durable. However, depending on the moisture content of the air, I have found that it sometimes will cause print book covers to curl in high-humidity environments (since only one side of the book cover is coated with the laminate). To avoid this, always specify a “lay-flat laminate.” (By now, this problem may have been remedied.) In addition, laminates may show fingerprints less than UV coatings, particularly over darker, heavy-coverage printing ink.

More Design Considerations

These cover coatings can really make a print book stand out on the shelves and in the reader’s hands. This is one strength of print books over e-books: they enhance the tactile experience of reading.

To reap the highest benefit of cover coatings, keep in mind that you can “spot-coat” a design as well as “flood coat” a design. That is, you can (for instance) apply a gloss varnish to all of the interior photographs in the text of a book. This will make the images seem more crisp and bright. (It will also make reading easier on the eyes, particularly if you start with a matte or dull press sheet and only spot coat the photos. This is because the glare of a gloss-coated sheet increases eye-strain over time.) Flood coating refers to covering the entire sheet; spot coating refers to applying a coating to only a limited portion of a page.

On book covers (or even in book texts), you can contrast a spot gloss coating with a spot dull coating, accentuating certain design elements while playing down others. So with this in mind, you can use various coatings to enhance the aesthetics of a printed piece.

(This technique lends itself primarily to varnishes, although you can contrast gloss and dull UV coatings and aqueous coatings as well. However, it is wise to discuss this with your printer, because there is more involved in applying spot UV and aqueous coatings than in using spot varnishes.)

To add spice to the design, keep in mind that for varnishes you can also add a slight bit of pigment to the coating. (This would provide a slight tint to an image, allowing you to print the faintest of images on the background of a book page or cover.)

Another option that’s reasonably new is to apply textured varnishes and UV coatings. For instance, you might add a slightly rubbery feel to the cover of a book with a soft-touch flood coating, or you might add a texture with “reticulating” varnish. Or you might even apply a textured UV coating that simulates the feel of pigskin on a photo of a football.

Always Leave a Window (a “Knock-out”)

It’s hard to write with a ballpoint pen on a coated surface, particularly if the coating is thick like a UV varnish. This probably won’t be a problem on a print book cover, and some inkjet presses can print variable data information–addresses, for example–directly on some surface coatings (on promotional mailers, for instance), but the rule I’ve followed has always been to leave a window (i.e., an uncoated area) over any portion of a coated sheet that will need to be marked in any way with a pen.

Let’s say you’re printing a poster, and you want to cover everything with a gloss coat to make the photo stand out. But the teachers at the school that will display the posters will need to hand write information on the bottom of the poster. Or maybe they will need to fill out a portion of a mailer you have produced, and you’ve coated everything on the message side and the postal side, but you need the prospective client to fill out the return portion. Always think ahead and leave a window. (You would be surprised at how easy it is to forget and make this mistake.)

This entry was posted on Sunday, January 23rd, 2022 at 2:41 pm and is filed under Paper Coatings. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.