Page 189 - Graphic Design and Print Production Fundamentals

Graphic Design 177
sheet of letter (8.5″ x 11″), 80# text, is much thinner than the same size of 80# cover. Table 6.1 shows
common basis weights, parent sheet sizes, and typical uses.

Table 6.1 Paper weights, sizes, and uses

Parent
Basis Sheet Typical Use
Weight
Size
Historically used as writing paper and typically uncoated. Standard office paper is 20#
17″ x
Bond bond, while colour prints are more commonly done on 24# or 28# bond due to the need for
22″
higher opacity.
20″ x Used for paperback book covers, business cards, post cards. Business cards have typically
Cover
26″ been 100# cover, but have been trending toward higher weights of 110# and 120#.
Used for magazines and posters. Relatively thin sheets with higher opacity. Magazines
25″ x
Text typically use a coated text weight paper for both the cover and the body. Typical weights are
38″
70# to 100#.
25.5″ x
Index Used for index cards and tab stock. Tab stocks are typically uncoated 90# index.
30.5″

Although basis weight is used as the primary weight on a paper label and description, a digital press will
typically use grammage to define the weight property when assigning a paper to a tray. Paper weight
is one of the key characteristics that affect many parameters on the digital press, including how much
vacuum strength is used for feeding, how much charge is required to transfer toner to paper, and how
much heat is required to maintain a consistent fusing temperature to bond toner to the paper, among
others. Entering the wrong values for the paper weight can cause paper misfeeds, poor image quality, or
toner not adhering to the paper. Using grammage simplifies data entry and avoids errors due to incorrect
basis weight selection for the numeric weight value. It may, however, require one to do a conversion
calculation if only basis weight is provided. The following conversion factors can be used to do these
calculations.

Conversion Factors:

Bond (lbs.) x 3.7606 = gsm
Cover (lbs.) x 2.7048 = gsm
Text (lbs.) x 1.4805 = gsm
Index (lbs.) x 1.8753 = gsm

Grain Direction

In the paper manufacturing process, a slurry of fibre travels over a high-speed mesh conveyor belt
that is oscillating side to side. This action and movement causes the fibres to interlace and develop a
predominant alignment along the direction of movement. This predominant alignment of the fibres is
called grain direction. Short grain refers to fibres running parallel to the short dimension of the sheet,
and, conversely, long grain refers to fibres running parallel to the long dimension of the sheet.