Spot Colors:
Yet another landmine in printing

A spot color is a specially mixed ink that is applied on the printing press, as opposed to a mix of the four inks which make up process printing. Spot colors can be produced in a much more vibrant range of colors, and can have special characteristics which aren't available in process inks, such as day-glow or metallic ink.

Because they only use one ink roller, one plate, and one negative, spot colors can reduce the cost of printing if you limit your ink choices to black and one spot color. For example, if you choose to print a red and black letterhead in process inks, you will actually need three inks on three rollers (with associated plates, etc): Magenta, Yellow, and Black.

However, if you are already printing a full-color piece, adding a spot color will dramatically increase the cost of printing. You will add one more color to the four colors needed to produce, for example color photographs. It then is a five-color job requiring five inks, five rollers, five negatives, five plates, etc.

Many companies make spot colors, but the most popular is Pantone, Inc. They not only make and sell inks, but they have a process which enables printers to mix the exact same colors from a set of base inks.

CONVERTING SPOT COLORS TO CMYK

Besides the 4 standard process colors (Cyan, Magenta, Yellow, & Black), there are thousands of spot colors. Your computer can convert all of these spot colors to CMYK with the click of a button, but BEWARE! The gamut, or range, of colors that CMYK can produce accurately is extremely limited. This means that most spot colors, when converted to CMYK, will not match the original.

Some spot colors convert well to CMYK, like Pantone 201, Pantone 297, Pantone 363, and Pantone 491. These are just some of the colors that convert very well.

On the other hand, Pantone 184, Pantone 2735, Pantone 314, and Pantone 527 do not convert well into CMYK at all. They will lose their brilliance and seem dull and lifeless. Check with your printer for more information on which colors will convert well and which ones will not.

Or, you can purchase a Pantone to CMYK conversion book that shows you exactly how Pantone colors they will appear in CMYK. Pantone Inc. is located at www.pantone.com.

NAMING SPOT COLORS ON THE COMPUTER

When naming spot colors on the computer, be careful to use the EXACT SAME NAME in all of the programs which use that color. If you create PANTONE 185 CVC in Adobe Illustrator, then create Pantone 185 CV in Quark XPress, you have actually created two different colors as far as the computer is concerned. The fact that your eye sees the same color doesn't mean squat. They will not separate onto the same plate because their names are not EXACTLY THE SAME.

CREATING DUOTONES WITH SPOT COLORS

When you create a duotone in PhotoShop with a spot color, you MUST change the spot color's screen angle in Quark XPress or PageMaker (you can also change it in PhotoShop, but it is more difficult. Check your manual). Spot colors screen at 45°, the same as black, by default.

If your duotone is made up of black and a spot color, and you don't change the screen angle of the spot color, then your negatives will have the exact same dot pattern. This will result in the dots printing one-on-the-other (example on the right, below), and you will not have a duotone effect, as the black will blot out the other color.. In fact, if the printing press goes even slightly out of register, you will get a horrible moiré pattern.

In a correct black-and-spot-color duotone, the spot color has a 75° screen angle (offset 30° from the 45° black screen angle). This angle combination will help to prevent unpleasant moiré patterns when it is printed. If using two spot colors for a duotone, one angle should be set to 45° and the other to 75°. Always double check that changing your screen angles in one area doesn't create a problem in another area!

Another note about duotones: It isn't advisable, in PhotoShop, to have the same curves set for each ink in a duotone, which is PhotoShop's default. (It is PhotoShop's default ONLY because they don't presume to know what effect you want to create, NOT because that is the suggested Curve combination.) Usually, the spot color is used for adding richness in the shadows, and should be considerably less intense in the highlights and midtones. Try some of PhotoShop's preset duotone curves, and experiment with how adjusting the curve on your spot color can effect the image.

Duotone curves are NOT adjusted using the Image>Adjust>Curves dialog box, but rather by clicking on the curve grid in the Image>Mode>Duotone dialog box.

Separations - Spot colors need special attention when sent to film
The CMYK Color Space - Limitations of process inks in printing
Mixing Colors in CMYK
Moiré - Patterns created by screens