Paper specifications (continued)
Category | Specification |
|
|
Grain | long grain |
| Note |
| If paper is greater than 135 g/m2 (36 lb) |
| use short grain. |
|
|
Moisture content | 4 percent to 6 percent by weight |
|
|
Smoothness | 100 to 250 Sheffield |
U.S. paper grades
The U.S. paper grading system has evolved from custom and usage rather than from a technical background, resulting in similar papers having different stated weights. For example, a 24# bond paper is exactly the same weight as a 60# book or a 60# text or a 33# cover. This is because basis weight is defined as the weight of 500 sheets of paper cut to basic size. The basic size for bond, book/text, cover, index, bristol, and tag are all different so the given weights for these paper grades might be different although the physical weight is virtually identical. The following tables will help clarify these differences. Note the difference in basic size for each grade, which affects the weight of
500 sheets of that grade:
U.S. paper grades: basic sizes and basis weights
Paper | Basic size | Basic area | Factor | Equivalent |
grade |
|
|
| basis |
|
|
|
| weights |
|
|
|
| (example) |
|
|
|
|
|
Bond | 17 by 22 in | 374.0 sq.in | 1.00 | 24# bond |
|
|
|
|
|
Text | 25 by 38 in | 950.0 sq. in | 2.54 | 61# text |
|
|
|
|
|
Book (coated | 25 by 3 in | 950.0 sq. in | 2.54 | 61# book |
or uncoated) |
|
|
|
|
|
|
|
|
|
Cover | 20 by 26 in | 520.0 sq. in | 1.39 | 33# cover |
|
|
|
|
|
Bristol | 22.5 by 28.5 in | 641.25 sq. in | 1.71 | 41# bristol |
|
|
|
|
|
Index | 25.5 by 30.5 in | 777.75 sq. in | 2.08 | 50# index |
|
|
|
|
|
152 Chapter 5 – Media specifications | EN |