Printing & Design Tips: February 2001, Issue #7

Specifying Paper for Printing

The more you know about the characteristics of paper, the better able you will be to save money when specifying paper for your printing jobs. In fact, if you specify the qualities you require in your paper, rather than a specific name brand, your printer may be able to offer several acceptable options.

Each paper stock possesses the following characteristics: surface texture, brightness, color, whiteness (if you specify a white sheet), opacity, grain direction, weight, bulk, caliper, and size.

Uncoated and coated paper have different surface textures. In the papermaking process, uncoated stock has been compressed between metal rollers (calendared) only to a limited degree, yielding vellum, antique, wove, and smooth surfaces (from rough to smooth, depending on the amount of calendaring). Coated paper varies from roughest (matte) to smoother (dull) to smoothest (gloss), also depending on the amount of calendaring. Papermaking machines can even impress such textures as "linen" and "canvas" on paper. The smoother the paper, the better the "holdout" (the better the ink sits up on the surface of the paper rather than being absorbed into the fibers).

Brightness refers to the amount of light a sheet reflects (0 to 100 percent, with a crisp white sheet often exceeding 90 percent). Whiteness refers to the color of the reflected light (either yellow-white or blue-white, i.e., warm or cool). Brightness and whiteness affect readability (too much light tires your eyes when reading long blocks of text) and the crispness of photos (too little light reflected back makes photos seem dark or muddy).

Paper color is tricky. It changes the color of the ink, so always request printed samples. Colored stock is also more expensive than white stock because of the dyes used and because it is less in demand. Off-whites, referred to as cream, ivory, etc., are a good option for some jobs, but the names differ from paper mill to paper mill, and the appearance will change among paper batches produced at different times.

Opacity determines show-through. A sheet with high opacity will prevent solids, screens, and halftones from being visible through the opposite side of the sheet, which could otherwise be quite distracting. Colored sheets are usually more opaque than white sheets. This quality is rated on a 1 to 100 scale. Most sheets fall in the 80 to high 90 range.

Weight is based on the size of 500 sheets (a ream) of paper. A ream of 80# cover, measured at 20" x 26", weighs 80 pounds. The same paper in text weight still weighs 80 pounds but the sheet size is different: 25" x 38". It is therefore a thinner sheet. Of course these sheets can be cut to a smaller size. This is just a convention for precisely describing different grades of paper, such as bond, offset, etc. Another scale is in points (thousandths of an inch). You might, for instance, specify a cover for a perfect-bound book as a 10 pt. sheet. To be safe, always ask for samples.

Caliper is the thickness of paper when measured with a micrometer. It is related to bulk, which is a relative measure of the thickness as related to the basis weight of a sheet. For instance, 75# Hi-Bulk is thick enough to pass US Postal regulations for reply card thickness (7 pt.). Another sheet of this weight might have been further calendared and its fibers compressed more, yielding a thinner sheet. Lower bulk reduces opacity. Higher bulk will increase the overall thickness of a book. Therefore, it helps to know a paper's measure in pages per inch (caliper).

Finally, grain direction refers to the direction the fibers of a sheet have aligned during the papermaking process. In grain long papers, the fibers run parallel to the length of the sheet. In grain short paper the opposite is true. Paper folds better parallel to the grain direction, but is stronger against the grain. Also, paper can expand against the grain when exposed to a press' dampening solution or moisture in the air. Therefore, to maintain tight register a job on this paper would be run grain long.

All of these qualities affect the runnability and printability of the paper, as well as its appearance, so listen to your printer's advice. However, don't hesitate to request samples, both printed and unprinted, of any sheet suggested by your printer. Only by actually seeing a printed sheet can you know whether a particular paper will work for your own job.

[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.]