Printing & Design Tips: April 2003, Issue #21

The Effect of Paper Color on Ink Color

I received a color quiz from an ink company (Flint Ink) many years ago. It has a little window through which you can see fifteen paper swatches. On the cover is the question: "Which swatches are printed with the same ink"? I have showed this quiz to numerous people over the years, and most point out two or three or five colors they think are the same. What is the catch? The colors used on all paper swatches are the same. It is the paper color of each swatch that changes.

Most, but not all, inks are transparent. Light travels through the ink film, bounces off the substrate (paper, vinyl, or whatever), and is reflected back to the eye. The color of the paper dramatically influences the perceived color of the ink.

The color quiz includes samples of coated and uncoated sheets: coated including dull, matte, gloss, and cast coated, and uncoated including Kraft paper (natural and bleached). The coating makes a difference in the color as do the impurities (such as the lignin in groundwood stock) and the formation of paper fibers. Bright sheets (sheets that reflect back a large amount of light) make the blue of the ink quiz appear brighter. White sheets (sheets that reflect back clear, white light without a particular color cast) make the ink appear whiter.

Clearly this is not something that can be adequately conveyed in words. In some cases the differences are subtle, and in others the blue looks vastly different. I think it is enough to realize just how dramatically paper can affect the perception of ink color.

With this awareness, consider that some inks are opaque (opaque white, for instance) and are not affected by the color of the substrate. This can be used to your advantage, as will be shown in the next section. Four-color process inks are always transparent.

The best way to achieve your aesthetic printing goals and not be unpleasantly surprised is to ask for an ink draw-down on the stock you are using. Or, choose a stock and specific inks based on sample books printers and paper companies are eager to provide. These books will show various effects (duotones, for instance) on particular paper stocks, with or without varnish. Using such books you can see what your printed piece will look like (for the most part) before you commit ink to paper. Discuss your goals with your printer, ask for samples, and even consider attending a press check.

Underprinting

Everything stated above need not be a problem. On the contrary, using the reciprocal influence of ink and paper, you can create unique effects that provide superior design as long as you understand and control the effects of paper on ink and ink on paper.

For example, you might expect a halftone printed on a gray stock to have highlights only as bright as the unprinted sheet. If so, you would be mistaken. In fact, you can underprint an opaque white on a portion of a subdued, gray sheet, then, after the ink has dried, you can print a gray and black duotone over the opaque white. If, for example, you had preprinted the opaque white under a figure bathed in sunlight in a portion of the photo, this figure will seem to jump off the page once the duotone has been printed. The underprinting of white will make it seem as though sunlight were actually lightening this portion of the image.

You can do the same by underprinting match red under a four-color image of flowers. When the red has dried and you surprint the four-color flowers, you will see just how much more dramatic the flowers will be than if printed only in process inks. The match red underprinting will sharply increase the saturation of the red flowers in the image.

If you approach layered printing in this way, you will pay more than for four-color offset since you will be using more printing units (ostensibly on larger presses). You will also need multiple passes through the press with drying time in between. But for special printed products, such as an annual report, this can make for a superior design product that really stands out.

As with the first section in this issue of Quick Tips, consider the paper stock and the opacity of the inks. Consider also whether you will wet-trap or dry-trap the inks. Wet trapping means running the base color and surprinted colors within the same pass through the press. This allows for a more subdued color effect (while also requiring more printing units). The opposite, dry-trapping, means waiting until the first pass of inks has dried, and then printing the second pass of inks. Printing four-color process over dry-trapped opaque white, for instance, will allow for the maximum "pop" of the four-color image off the page. The effect is far more dramatic than with wet-trapping, which would only provide a subtle lightening of the four-color image.

Finally, consider adding a dull and/or gloss spot varnish to separate portions of the images to make them advance or recede. Or consider adding varnishes tinted with ink for a subtle, almost ghostly effect.


[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]