Chapter 7: Paper

NORTH AMERICAN SHEET SIZES

Most paper manufactured and sold in North America is measured in inches. Sheet sizes are based on trimming a quantity of 8 1/2" × 11" (216 × 279 mm) items or pages from a single sheet with a minimum of waste. Some sheet sizes, such as 11" × 17" (279 × 432 mm), are exact multiples of the 8 1/2" × 11" (216 × 279 mm) inch standard. Other sheet sizes are also based on multiples of 8 1/2" × 11" (216 × 279 mm), but are slightly oversized to accommodate on-press requirements. For instance, a 23" × 35" (584 × 889 mm) inch sheet would yield sixteen trimmed 8 1/2" × 11" (216 × 279 mm) flyers or a sixteen-page signature while allowing a narrow margin for bleeds, grippers, and color bars.

Printers in North America use sheets measured in inches with sizes based on multiples of 8 1/2" × 11" (216 × 279 mm) inches.

NORTH AMERICAN SHEET SIZES AND METRIC EQUIVALENTS

INTERNATIONAL, OR ISO, SHEET SIZES

Papers manufactured and sold outside of North America are based on 1 square meter. The International Standards Organization (ISO) system of paper sizes applies to all grades of paper and paper board and consists of five series of sizes: A, RA, SR, B, and C. Within each series, each sheet is twice the size of the next smaller sheet and half the size of the next larger sheet.

The starting point for ISO sizes is the AO sheet, which measures 841 × 1189 mm (33 1/8" × 46 3/4") and has an area of 1 square meter. Each smaller size is a fraction of the A0 size. For instance, the A1 size (594 × 841 mm) is half of A0, and the A2 (420 × 594 mm) is one quarter of A0. Sizes larger than A0 retain the same proportions and a numeral prefix is added to the letter. For example, a 2A0 sheet is twice the size (1189 × 1682 mm) of an AO sheet. The A series is used for general printed matter, including letterhead and publications.

ISO A SHEET SIZES AND INCH EQUIVALENTS

In addition to the preceding A sizes, there are two series from which A sizes can be cut. The series prefixed R and SR are designated as parent sheets for A sizes with tolerances for accommodating bleeds and extra trims.

ISO R and SR Sheet Sizes and Inch Equivalents

The B series is about half way between two A sizes and is intended as an alternative to the A sheets. ISO B series sheets are narrower than the A series and are usually used for posters and wall charts. The B series is based on a B0 size of 1000 × 1414 mm.

ISO B Sheet Sizes and Inch Equivalents

The C series is used for folders, postcards, and envelopes suitable for stationery in the A sizes. (For more information on the C series as it pertains to envelopes, see Chapter 8, Envelopes and Folders.)

ISO C Sheet Sizes and Inch Equivalents

BASIS WEIGHT EQUIVALENTS

In North America, the term basis weight or ream weight is used to define the weight in pounds of a ream of paper cut to a given size. (A ream is defined a 500 sheets of the basic size of a paper.) Basis weight is stated in pounds as represented by the # symbol.

The basic size of a sheet varies according to its grade. (Note that the basic size is only one of many standard sizes for each grade and is only used as a means of determining basis weight.) Basic sizes used to determine basis weight of some common papers are listed below:

Because of the size variations, paper grades that share the same basis weight may not look and feel as though they share the same basis weight. For instance, when comparing a sheet of 65# text and 65# cover stock, the cover stock will look and feel much heavier.

The following list of equivalents should help to define the basis weight differences between various grades.

GRAMMAGE

Outside of North America, the weight of paper is measured in grams per square meter (gsm). The grammage system measures the weights of all papers without taking into consideration their size or grade. This system standardizes a ream at 500 sheets and defines a sheet as 1 square meter (A size). The term grammage is used to define the basis weight of all grades of paper measured in grams per square meter.

The following list gives some basis weight and grammage equivalents. Because North American basis weights are based on different basic sizes, the progression of weight conversion may not seem to be as logical as the basis weight comparisons on the opposite page.

Converting Basis Weight to Grammage

To convert the basis weight of a paper to its grammage, look up the sheet size in the left-hand column of the chart below. “lb." means pounds (basis weight).

CALIPER, BULK, AND PPI

Paper thickness is defined as caliper. Caliper is measured in thousandths of an inch and expressed as point size. One point equals 0.001 inch. Stock that is 0.007 inch thick is described as 7 point or 7 pt. Points are most often used when referring to cover stock. It is also used by the U.S. Postal Service, which states its thickness requirements in calipers.

The term bulk is used to refer to the thickness of paper relative to its paper weight. A paper’s finish will have an impact on its bulk. For instance, coated papers tend to be thinner than uncoated papers and have less bulk for their basis weight.

Publishers often state bulk as pages per inch, or ppi. Below is a comparison chart that compares caliper size with pages per inch.

BASIS WEIGHT/CALIPER EQUIVALENTS

The following chart gives an approximate caliper thickness for the different basis weights of some common papers. Because a paper’s finish also affects its thickness or bulk, calipers are also given for common finishes.

PPI FORMULA

Determining pages per inch can be important for determining the thickness of a finished publication. To calculate the number of pages per inch, calculate the caliper (points) of eight pages (four sheets) then divide the number of points into eight. In the following example, four sheets of a hypothetical paper measures 0.016 inch in thickness.

Example: 8.000 ÷ 0.016 = 500 ppi

FINISHES

In addition to considering basis weight or grammage, caliper, and sheet size, paper comes in finishes that range from smooth to textured. Uncoated papers also come in an assortment of finishes that are embossed into the paper as it is dried. These include linen, laid, and cockle textures.

Coated papers are available in uncalendered (an unpolished coated surface), machine calendered (a smoother finish), and supercalendared (highly polished) finishes—processes that affect the smoothness or glossiness of the surface. These can range from a matte or dull-coat finish to the high-gloss sheen of a cast-coated stock.

GRAIN

Grain refers to the alignment of the fibers on a given sheet of paper. The grain direction of a paper can affect folding accuracy and degree of stiffness. Paper tears and folds more easily when it is torn or folded with the direction of the grain. Folding paper against the grain can result in a rough or uneven fold. Business cards cut so that the length of the card runs in the direction of the grain tend to feel flimsier than cards cut with their length against the grain. It’s best to check with your printer to determine the best way to set up your document for optimum grain direction.

Paper is manufactured on rolls with the fibers aligned parallel to the edge of the roll. Sheets are cut from these rolls. When fibers are parallel to the length of the sheet, the stock is described as grain long. When fibers run parallel to the width of a sheet, the stock is grain short. Grain direction can affect printing stability, and long-grain sheets are generally preferred for multicolored jobs. Printing press sizes can sometimes necessitate the use of short-grained paper, so it’s best to check with your printer before preparing your files.

Getting the Most from a Sheet

Minimizing wasted trim involves understanding how many trimmed pages will fit on a standard paper size. Use the following chart to determine how many pages will fit on North American standard paper sizes. (Note: Trim size does not include bleed allowances.)

PAPER ESTIMATOR

Consult the chart for determining how many pieces can be cut from a single sheet of paper (see page 67), then refer to this chart for estimating the amount of paper needed for a given quantity. To determine how many sheets of paper will be needed for a job, check the number that will fit on a single sheet in the left-hand column. Then find the corresponding quantity by reading across on the top column (Example: If 16 pieces will fit on a single sheet, printing a quantity of 3,000 would require 188 sheets of paper.) Note that quantities given do not account for spoilage. Spoilage percentages are usually determined by individual printers, depending on the length and complexity of the press run and the complexity of the binding process.

PAPER USAGE GUIDE

Use the following chart as a general reference guide for determining which papers are most suitable for a given job.