Printing With Spot Color Inks
The methods that are commonly in use for printing on the surface of a CD are very different from the methods used to print the paper products. Whereas offset lithography with "SWOP CMYK" inks is used in the manufacture of the booklets and traycards, screen printing with spot color inks is standard for disc label printing. CMYK process printing is an option for the disc, but it costs extra, it's tricky to get it to look right, and it's rarely the best choice. Usually, discs are printed using inks mixed according to formulas established by the Pantone(R) corporation.
Pantone swatch books contain samples of ink from their catalog. They can be purchased from a variety of sources: computer catalogs, art supply stores, etc. The most complete is the Pantone "Formula Guide," shown here. A book with fewer inks, but great practical utility for designers working on CD/multimedia package design is the "Solid to Process Guide," which has side by side comparisons of the Pantone inks and their closest CMYK approximations. The cost is around $70-100 per book.
|Swatch books are important because there isn't a computer screen in the world that does a very good job of representing the actual colors of all Pantone inks. It's best to design with the mouse in one hand and the swatchbook in the other. Adobe, Quark and the rest of the software companies understand this dilemma, and the naming conventions that they've adopted for referring to ink colors reflects their awareness.
The Suffixes: C, U, CV, CVC, CVU
Pantone 285 is a blue ink that's mixed from the ingredients Reflex Blue (6 parts), Process Blue (2 parts) and Transparent White (8 parts). In most swatch books, you'll find that Pantone 285 appears more than once, as 285C and 285U. Pantone 285C is Pantone 285 printed on coated paper. Pantone 285U is the exact same formula of ink, but printed on uncoated paper, resulting in a different apparent color.
|CV, CVC, and CVU stand for something else entirely. Pantone 285 CV is the "computer video" simulation of Pantone 285. Pantone 285 CVC is a more precisely named "computer video" simulation of Pantone 285, printed on coated paper. Pantone 285 CVU, is an analogous representation of 285 on uncoated stock.
It's important to understand these naming conventions, because CV, CVC, and CVU look different on your computer screen, although they all represent the same ink formula. Not only that, but it's common for page layout programs not to understand that they are the same color, and attempt to print multiple separations for the same ink!
So when you're designing, which is best? CV or CVC, generally, but be warned: even the mighty Pantone swatchbook fails to represent the actual color that will appear on the disc. That's because all of the methods available for previewing color assume that the ink will be printed on white paper. Inks tend to appear a little darker on the silver surface, for the same reasons that a red magic marker will create a darker streak on a grey piece of paper than it will on a white one. If you've got your swatch book in hand, be prepared for variation on the order of a half a shade (i.e. look at the swatch, and find the darker of its neighbors. Expect a color somewhere in the middle).
The difficulty of trying to match the color of the disc to the color of the insert
The human eye is not particularly sensitive to overall color casts, but it is very sensitive to side by side tonal variation -- if you show someone two slightly different purples 5 seconds apart, they won't necessarily make a strong distinction between the two, but if you show them the same two colors side by side they will immediately be able to recognize that there is a difference.
Since the printing processes are totally different, the ink types are totally different, and the manufacturing takes place at different locales, expecting the CMYK approximation of a Pantone ink printed on the paper insert and the actual Pantone ink printed on the (mostly) silver disc to match precisely is a dangerously optimistic, unless special steps are taken. In general, try to avoid designs that will be adversely affected by a mismatch, such as:
- a disc that has a solid color that faces the "same" solid color on the back of the insert when you open the jewel case, or
- a disc that attempts to "blend into the background" printed on the interior of a traycard.
However, if color matching is crucial to the integrity of your design, you can:
- Find the CMYK blend from your layout that you're trying to match in the Pantone Solid to Process Gude, and select the closest Pantone spot color.
- Purchase a Matchprint, and select your Pantone off of that. You can get pretty close with this method.
- Wait to choose a Pantone color for the disc until you've seen the paper materials. This is generally effective, but can add significantly to your turnaround time.
- Purchase a one-off proof print of your disc, where the disc manufacturer makes a screen, mixes the ink, sets up the machine, prints 1 disc, shuts down the machine and tears everything apart. This is the only proof for discs that approaches the accuracy of color laminate proofs such as matchprints. However, it costs hundreds of dollars, so it's only cost effective if you're doing a very large replication run.