Film laminating is accomplished by gluing a film (generally polypropylene) down on top of the printing side of a jacket or cover. It achieves very high gloss and although the film itself can be scuffed, virtually nothing is going to scuff through to the ink.
UV coating is done by running the paper, through a special coating machine, flooding the printed surface with a liquid ultra violet material, then using a blade to smooth it and even it out, then a UV drying tunnel to cure it. The final product is not quite as glossy as film laminating but when it cures, UV coating is harder than film and it is more resistant to scuffing or scratching. While film laminating protects against scuffing of the ink, the film itself is soft enough to pick up and show some scratch marks. UV coating resists scratches very well.
A year ago we considered converting a printing press to UV coating so we could do it in-house and lower our price. However, we discovered that doing UV on a printing press, while inexpensive, does not do the job nearly as well as doing it on a UV coating machine. The UV coating machine puts the liquid on about twice as thick as a press can and it mechanically smoothes it out so it ends up looking much better and giving more protection then UV put on with a printing press. Thus, we still farm the UV out and have it done on a full fledged, UV coating machine.
You are probably aware that UV coated covers will generally lie flat and not curl. Film laminated covers also generally lie flat. However, when the surrounding air is warm and humid, a film laminated cover will curl. This is its major disadvantage for covers.
The disadvantages for UV are a slightly less "pretty" appearance and the fact that, when folded around the book's spine, the hard coating can crack, revealing the white fibers of the paper beneath the ink. This is a rather subtle crack and is usually not noticeable unless the entire spine is printed, but it can be a problem.
From a manufacturing standpoint, UV coated covers are easier to work with in the perfect binding process because they lie flatter and they are more slippery, allowing them to pass through the binder more easily. This slipperiness, however, is a problem if the books get shrink-wrapped in multiples. The top books tend to slide off the stack so shrink-wrapping in groups becomes a real chore. Fortunately, there is very little reason to shrink-wrap UV coated books in groups.
In our experience, film laminating and UV coating are about equally popular for soft bound covers, with maybe a slight edge for UV. However, for jackets, since curl is not a problem (the book covers hold the jacket in place), we film laminate about 20 jackets for every one we UV coat.
How's that for telling you more than you ever wanted to know about cover coatings ... and still not reaching a definite conclusion.
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1. Mechanical Preparation: Basically most of our cover and jacket art comes to us as either computer generated art or as art and overlays done by hand and using a conventional typesetter. Computer generated art is still very much in the minority but it is growing and we'll discuss it first.
While many of these mechanicals are well prepared and easy to work with, computer generated art can present problems for the printer. These problems include things like wrong trim sizes and spine bulks, poor screen quality, no copy allowance for bleeds, inadequate lap (shrinks & spreads that don't fit properly) and elements for different colors that are all on one piece of copy. If separate color elements are on top of, or even just touching each other, it can be very difficult for the printer to separate them with a camera. They should be on separate mechanicals.
If the person preparing your computer art or negatives has any questions at all about what the printer needs, they should always call the printer to find out what they can best work with. Computers can do a great job creating a mechanical but we still receive art that is almost unusable in the form it is submitted. This happens when the computer operator didn't fully understand what the printer needs in order to create a set of properly registered negatives. Communication between the computer person and the printer's layout people can avoid a lot of grief in this process in addition to saving time and money. A phone call can be really helpful.
Creating elaborate art by hand probably will never achieve the accuracy and fit that well done computer generated art can. Hand cutting rubyliths for copy fit involving traps, etc. just isn't able to give the printer the precise laps that are needed for accurate register of color on the press. If your cover art is going to be created conventionally (not on computer), the printer, or at least Thomson-Shore , would actually prefer that you just put the basic type and FPO's for illustrations and graphics down on one board and indicate on a tissue overlay what this art needs to do when printed.
We would prefer to make our own separate negatives for each color rather than you trying to create copy for each color. The printer can also do things like drop in shadows and outlined type easier at the negative stage than you can do it on your mechanicals. We would prefer you to leave your illustrations and graphics as separate copy. We would then shoot and posifion them per your FPO'S. Ths gives the printer a little more flexibility to create the right traps and adjust for correct bulk, trim, etc...
In summary, conventional (non computer generated) mechanicals are easier for the printer to fix if there are problems with the copy and art but while computer generated copy can be tougher for the printer to fix, if prepared properly it's quicker to get to the final film stage. Either system works well if the designer or type setter is familiar with what the printer needs. That's the key.
2. Reverses: We prefer to have all type as black on white. If you want type handled as a reverse, let the printer make their own reverse negative. Also, if you reverse small, thin type out of a background color, it is very apt to create a problem by filling in. Press operators tend to run fairly heavy amounts of ink when they print a solid and this could plug up fine reverse type. If you want a bar code on the cover, it should always print on a white background and not over a solid or a screen. The bar code reader will not work if the bar code is an overprint or if it is a reverse.
3. Screens: When you want to screen a piece of line art, give the printer the screen percentage you want and let them drop the screen in. It is difficult to reproduce a screen by photographing one that the designer pasted down on the carnera copy.
4. Metallic Ink: There are now about 250 colors of metallic ink available and a lot of the new ones are tricky to run. Depending on how much actual metallic is in the mix, the ink may or may not be opaque. This will effect how the ink will trap. Some can overprint and trap and some can't. If you print a metallic opaque ink on top of a PMS ink , it will usually totally cover it. Metallic inks are slow drying so if you want to print over the metallic, it requires an additional press run after the metallic is dry. Metallic inks lose their snap if they are used on non coated covers. They have low rub-resistance and should be coated with either UV or film lamination. Fortunately, metallic ink looks great after being coated.
5. Borders: It is very difficult to maintain a border of anything less than 3/8" on a cover or jacket. The mounting of a cover on a book has a pretty wide tolerance and if you vary by 1/8" on a 1/4" border, it's going to be obvious. Also, if you run art right up to the spine then stop it, you are apt to get books with some register problems at the spine.
6. Miscellaneous: If your art bleeds across the entire cover, either be sure you figure the spine bulk accurately or else give the printer ample copy in case more art is needed to make it bleed. On cover illustrations, we would prefer to receive your art as separate illustrations that we can size and strip, rather than already pasted down on the mechanical. When you prepare the mechanical, be sure you give complete color break instructions and that the mechanical is set up for the proper trim size. Once again, if you have any questions at all about how to do something, call the printer and ask to speak to someone in cover and jacket layout. They would love to help you out.
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In four color process printing, if you want a solid background color that is not one of the four process colors, the color separator generally does that with a trap of two or three colors. They have charts that show what screens of the process colors are used to create most any PMS color that the designer wants.
The problem with this is that these traps get close to the right color but do not hit it on the head. Some traps miss the intended PMS color by enough to cause the designer some concern.
To help identify this problem in advance, PMS has developed a new PMS book called Pantone Process Color Simulator 747SR. This book shows the correct PMS color and beside it the closest you get to that color with a trap. For designers who are concerned about exact color matching this book could be invaluable.
Basically the light PMS colors are the hardest to get close to with traps and they are often significantly different than the intended PMS. The darker colors can usually a closer niatch but they are three screen traps instead of two, so the variation from cover to cover is greater. The oranges and reds are always the toughest to get close to with traps.
In our press room, if we see that the traps are not close to the intended PMS, we will call the publisher to tell them. The alternative is to do away with the trap and just print that particular color as an additional color. Usually, however, the screens that were used to create the trap have to be redone and this adds to the $200 additional cost of printing the extra color.
To see the extent of this problem, check out the PMS Process Color Simulator. Hopefully your designer has one. If not, you can get your own for a mere $200 by calling 2Ol-935-5500 or faxing to 201-896-0242. If you do many four color covers and jackets it could be a good investment.
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