Commercial Printing Processes
TPC November 2001
Barbara Manning
Agenda
 Nine types of
commercial printing
processes
 Offset Lithography
 Color theory -additive and
subtractive color
 Pre press, halftone
screens and film
stripping
Nine Printing Processes
 Offset lithography

type is offset from the printing plate to a
blanket then to the paper.
 Engraving

ink wells shaped like the type transfer image
direct to the paper -- ink surface is raised off the
paper
 Thermography

treated inks, heat dried to rise (like bread) from
the paper surface
Printing processes
 Reprographics

copying or duplicating (Xerox or Kinko’s)
 Digital printing

printing direct from computer files (Giclée, IRIS
continuous tone printing)
 Silk screen

ink is pressed through a sieve onto many surfaces
Printing processes
 Letterpress

relief image metal plates are inked and pressed
into the paper
 Flexography

relief image photopolymer plates are inked and
pressed into paper
 Gravure

volatile inks are sucked from ink wells at high
speeds
Offset Lithography
 Based on the principle that ink and water
don’t mix.



Images are photographically reproduced on
printing plates which are dampened first with
water, then with ink.
Ink adheres to the image area, the water to the
non-image area
The image is transferred to a rubber blanket
(offset) and then to the paper.
Offset lithography
Offset web press
Reproducing Color
 Three essential elements to seeing color:


Light, an illuminated object and an observer
At low light levels colors look different
• why fire trucks are no longer painted red


In bright daylight we can see more colors, more
contrast and more saturation
The color spectrum shows the range of color
visible to the human eye.
• White light is a mixture of all the visible colors
• It’s called Additive Color
Additive
Color
The visible spectrum
Used in monitors.
Primary Colors are
Red, Blue and Green
When combined it
produces ‘white’
light or the
combination of all
visible colors.
Additive color
Primary Colors are Red, Blue and Green
When combined it produces ‘white’ light or the presence
in equal strengths of all the colors.
Subtractive color complements additive color
Subtractive
Color
Combines pigments that
absorb or filter light.
Used in any pigment (ink,
colored pencils, crayons) on
a substrate
Primary colors are Cyan,
Magenta and Yellow
Combined they produce
‘black’ or the absence of
color.
Complementary Color
Additive
Colors
Subtractive
Colors
(also the primary printing colors)
Additive & Subtractive Relationship
It’s Complementary!
Place additive primaries at
the points of the triangle.
Subtractive primaries are
placed between the two
additives that combine to
create them
A subtractive color filters
out the primary color across
from it (the complement)
from white light.
Subtractive Colors act as a filter
The ink on the paper
absorbs blue, reflecting
green and red light
which you see as
yellow.
The ink on the paper
absorbs blue, reflecting
green see as green.
Hue, Value and Saturation
 Hue is identified as the color family or color
name (such as red, green, purple). Hue is directly
linked to the color's wavelength.
 Saturation, also called "chroma," is a measure of
the purity of a color or how sharp or dull the
color appears.
 Brightness, also called "luminance" or "value," is
the shade (darkness) or tint (lightness) of a
color.

Areas of an evenly colored object in direct light have higher brightness than
areas in shadow.
Hue, Value and Saturation
Halftone reproduction
 Printing processes can only print ink or leave
blank areas on the page

they cannot print different shades of a color
• A newspaper press can only print solid black or nothing.
 Photographs are continuous tone, that is they
contain various shades of gray between the
extremes of black and white.
 In order to overcome printing limitations the
halftone process was invented.
Photographic
Reproduction
Half tone
reproduction
Preparing
photographs
for printing.
Halftone Reproduction
 The traditional halftone
process converts
different tones into dots
of varying size.
 The eye has limited
resolving power and at
a distance,(the distance
from your eye to the
magazine) is tricked
into seeing these dots as
continuous tone.
http://www.ted.photographer.org.uk/photoscience_halftones.htm#Colour Reporoduction
Halftone Reproduction
 Beware of

dot gain
• dots gain size when transferred to the paper

moiré
• screen angles are not correct for 4c printing

register
• four colors are not EXACTLY aligned in inch thousanths

screen value
• 250 lpi screen used when the press can’t handle it

picking
• paper coating is picked off and transferred to other sheets

ink and water ratios
• too much or too little of either ruins the job

press speed
• too fast or too slow ruins the job
Knockout, mask, reverse & trap
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Sources

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Print Glossary http://www.tcnj.edu/~print/pages/glossary.shtml
Offset Printing process: http://www.flashprinting.com/Printprocess.html
http://www.howstuffworks.com/offset-printing2.htm
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Giclée Digital Process http://www.fineartphotographic.com/printingprocess.htm
Kodak Digital Learning Center http://www.kodak.com/US/en/digital/dlc/index.jhtml
Capturing digital images
http://www.kodak.com/US/en/digital/dlc/book3/chapter2/digColorM3_1.shtml
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Color Theory http://www.kodak.com/US/en/digital/dlc/book3/chapter2/index.shtml
Visible Spectrum http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l2a.html
Four Color Process Printing http://www.printingforless.com/creativepro/perfectpiece.html
MS Publisher tips http://www.printingforless.com/creativepro/publishertips.html
Color Separation software http://www.fastfilms.com/
Halftone reproduction http://www.ted.photographer.org.uk/photoscience_halftones.htm
Hue, Value and Saturation http://www.colorcube.com/software/docss/docss.htm
http://www.geocities.com/~jlhagan/advanced/color_psychology2.htm
http://www.pantone.com/products/products.asp?idArticle=110&idArea=16
Sources