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Properties

Given that paper component of most publications accounts for 40 to 60 percent of the total cost of the printed job, paper properties are very important. Among the most important characteristics to be considered when choosing from the hundreds of stocks available are: paper size and weight, smoothness and finish, brilliance and opacity, sheet strength and uniformity. The importance that each of these plays can vary from job to job, but this section will explain how and why some papers are better suited for some tasks than others.

Basis weights & basic sizes

Basis weight refers to the weight in pounds of 500 sheets of paper when it’s been cut to that paper’s standard basic size. For example, the basic size for bond paper is 17 x 22 inches. If 500 sheets (a ream) of bond is cut to its basic size of 17” x 22” and weighs 20 pounds, it is classified as 20 lb. bond. If a 17” x 22” ream of bond paper weighs 24 pounds, it would be 24 lb. bond, and so on. The chart to the right shows common paper types and their basic sizes.

Color, brightness & opacity

Color
The whiteness of paper is the measure of its ability to reflect the colors of light equally. The more evenly a paper reflects all colors of the spectrum, the whiter the sheet. Some papers may reflect slightly cool colors back to the eye and give the illusion that the sheet is actually brighter than white. There is no such thing as a pure white sheet of paper, since the white that we see is always influenced by environmental lighting and reflections from surrounding objects.

If white paper has a slightly warm appearance, it will not appear as bright as a sheet that reflects cool color, however, warm colors printed on a warm sheet will appear stronger. Cool colors printed on a cool white sheet are enhanced the same way.

Brightness
The whiteness of paper is the measure of its ability to reflect the colors of light equally. The more evenly a paper reflects all colors of the spectrum, the whiter the sheet. Some papers may reflect slightly cool colors back to the eye and give the illusion that the sheet is actually brighter than white. There is no such thing as a pure white sheet of paper, since the white that we see is always influenced by environmental lighting and reflections from surrounding objects.

Opacity
Opacity is the measure (as a percentage) of the amount of light passing through a sheet of paper and is greatly influenced by basis weight, brightness, type of fiber and filler. Papers containing more fibers and fillers generally conceal print on the reverse side. A paper’s thickness doesn’t guarantee that it is more opaque than a thinner paper. Some thinner papers may be more opaque because there are a greater number of fibers and/or fillers in their composition. Opacity is measured on a scale from 0-100. The higher the number, the more opaque the paper.

Grains & grades

Grain refers to the direction of the fibers in a sheet of paper. In long grain paper, fibers run in the same direction as the longest measurement of the paper. In short grain paper, fibers run in the same direction as the shortest measurement. With sheet paper, short grain direction is indicated by underscoring (or bolding) the dimension along which the grain lies, or by changing the order of the numbers.

Grade refers to the type or category of the paper contents that provide a level of brightness or surface characteristics used to determine the grade level of the finished paper stock. Grades are classified from “Premium” at the highest level to “5” at the lowest level. Some text and cover stocks are listed simply as A or B grades since fewer grades of the text and cover stock are produced.

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