In color book
printing, how to reasonably arrange the sequence of color overprint is
an important topic for the technologists. An important role of printing is to
copy the original artistically, which requires the printer to have a certain
artistic appreciation and grasp the expressive ability of color change.
Improper arrangement of color sequence may lead to color deviation, color mixing
and reverse overprint of printed matter; scientific arrangement of color
sequence will make the color of printed matter closer to the original, and even
strengthen a certain color atmosphere, so that the level is clear, the dot is
clear, the overprint is accurate, and the color is real, natural and
harmonious.
There are three reasons for the arrangement
of color order: the influence of ink overprint and the shortcomings of ink
pigment itself, the quality of paper and the ability of human eyes to identify
colors. The most fundamental reason is the printing ink itself is not
completely transparent, that is, the ink itself covering power. The ink after
printing has a certain covering effect on the ink layer before printing, so
that the color of the printed matter always focuses on the performance of the
latter color, or the mixed color of the latter color and the front color.
The starting point of choosing color
sequence is to flexibly arrange color sequence according to the specific
situation of the original, combined with the current process conditions, taking
into account the main aspects (such as tone reproduction, color reproduction,
text clarity, book printing uniformity and
printing repetition rate, etc.).
There are the following principles to arrange
color order:
1. Arrange the color order according to the
original content and characteristics. Printing is a means to express the
graphic design of the layout, and each color reflects different emotional
components. Therefore, the arrangement of color order must first consider the
original content and characteristics. Editors often choose the tone of layout
color when designing graphic layout. This tone represents the overall feeling
of the whole tone and becomes the dominant color in printing. In terms of
color, those with red, orange and yellow as the base tone are called warm tone,
while those with green and blue as the base tone are called cold tone. Due to
the reason that ink has the covering power, generally, the warm tone is used to
print black and green first, followed by magenta and yellow; the cold tone is
used to print magenta first, followed by cyan. Everyone hopes that the ripe
watermelon pulp is red, but they don't want to see the purple and green color
of the printed matter. Color order is different, color deviation effect is also
different. Therefore, the colors that need to be strengthened in the color
atmosphere of the picture can be printed in the last color.
2. Arrange the color order according to the
paper properties. Poor quality paper, considering its low whiteness,
smoothness, loose fiber, poor ink absorption, easy to drop powder and hair, you
can first print yellow ink to make up for the above defects of paper. When book printing at night, due to the discernibility
of human eyes, low brightness weak color ink should not be arranged in the
first color printing. The order of lightness of ink is: white < yellow <
orange < green < green < red < blue < purple.
3. Arrange the color order according to the
transparency of the ink. Transparency of good ink, two-color overlay printing,
the lower layer of color light through the upper layer of ink, to achieve
better subtractive mixing, showing the correct new color. If the yellow ink
used is transparent yellow, the order of four kinds of ink transparency is:
Yellow > magenta > cyan > black. Generally speaking, poor transparency
of the ink first printing, good transparency of the ink after printing.
4. Arrange the color sequence from the
advantage of overprint. Due to the paper deformation, expansion and other
objective defects, we can arrange the main colors of overprint products in two
adjacent color groups. Such as two-color machine, can be arranged in the same
unit to complete a printing, to avoid the existence of paper caused by paper
expansion and other problems. Large area of the field, you can arrange after
printing, to avoid the paper in the process of hand over rub dirty and other
problems. In addition, monochrome machine is in the first color "dry"
and then overprint the second color, and polychrome machine is "wet
pressure wet" process, so we should control the viscosity and ink amount.
That is to say, it is very important to arrange high viscosity ink to print
first and low viscosity ink to print later, otherwise it will cause the
disadvantage of reverse overprint.
5. Consider process factors such as plate
making. When printing, the difference of screen angle between two adjacent
color groups is at least 30 degrees, which is helpful to prevent color
deviation and moire.
6. Consider the color order according to
the cost. Cheap black and green ink first printing, high price magenta, yellow
ink after printing.
Generally, the pictures dominated by a
large area of scenery (cold tone as the keynote) are in black, magenta, cyan
and yellow color order. Arrange the black to print first, and the black is used
to draw the outline, which is convenient for other colors to overprint.
Transparent yellow final print, can be used to adjust the brightness of the
whole picture, forming a shiny, bright color. Generally, the pictures dominated
by characters (warm tone) adopt black, green, magenta and yellow sequence. Poor
transparency of the ink first printing, will not cover other colors. Magenta,
yellow after printing, make the character face ruddy, rich color, realistic
effect.
Color book printing
is a combination of technology and art. When we arrange the color
sequence of printing, we should consider it from an artistic point of view,
which can make the printing more artistic and meet the needs of readers.
