396 Graphic Communications
Sometimes, it is possible that the trim can be
used for another job. To fi nd out, utilize the same
type of formula.
Metric Paper Sizes
In many countries, the SI Metric system is used
for specifying paper size. The letters A and B each
designate a different series. The sizes in each series
are numbered 0 to 8 and represent the number of
times a sheet can be folded to obtain a particular
size. The sizes in a series are proportionate; any
smaller size is always half the next larger size.
In the A series, A0 has an area of 1 m2. The
sheet is not a true square but has a proportion of
5:7, Figure 21-19. Using 1 m2 as a starting point,
the subsequently smaller sizes are determined by
halving the larger size, Figure 21-20.
In the B series, the sizes fall between the A series
measurements and are used for unusual situations.
Standard metric sizes of paper are listed in Figure 21-21.
The nearest metric equivalent to the 8 1/2″ × 11″
standard sheet used in the United States is the A4
size. It is 210 mm × 297 mm (8.27″ × 11.69″).
Qualities of
Paper
There are several physical qualities that can
be used to make judgments about which paper is
most well-suited for a particular printing job. These
are color, smoothness, strength, brightness, and
opacity.
Color
Paper color and ink color must be compatible.
White paper is essential for full- or four-color printing.
It refl ects all the colors of the spectrum, while colored
paper does not. Colored paper can create a process
color value that is undesirable, producing a fi nished
piece that may not be what the customer expected.
Smoothness
Smoothness and texture both greatly affect
printability, or how well images show fi ne detail.
Smoothness varies with paper type. A smooth sheet
requires a very thin fi lm of ink to produce sharp
images. The opposite is true for rough papers.
1189 mm
841
mm
1m2
Figure 21-19. Size A0 is the basis for metric paper
sizes. It is 1 m2 in area, with a rectangular shape in a
5:7 proportion.
A2
A3
A4
A6
A5
A1
Figure 21-20. Metric paper sizes are simply halves of
larger sizes.
Designation mm Index
A0 841 1189 33.11 46.81
A1 594 841 23.39 33.11
A2 420 594 16.54 23.39
A3 297 420 11.69 16.54
A4 210 297 8.27 11.69
A5 148 210 5.83 8.27
A6 105 148 4.13 5.83
A7 74 105 2.91 4.13
A8 52 74 2.05 2.91
B0 1000 1414 39.37 55.67
B1 707 1000 27.83 39.37
B2 500 707 19.68 27.83
B3 353 500 13.90 19.68
B4 250 353 9.84 13.90
B5 176 250 6.93 9.84
B6 125 176 4.92 6.93
B7 88 125 3.46 4.92
B8 62 88 2.44 3.46
Figure 21-21. Alphanumeric designations, sizes, and
indices for the metric-size paper sheets. An index is
the decimal equivalent in inches.