Commercial Printing Processes

1. Commercial Printing Processes TPC November 2001 Barbara Manning

2. Nine types of commercial printing processes Offset Lithography Color theory -- additive and subtractive color Pre press, halftone screens and film stripping Agenda

3. 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

4. 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

5. 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

6. 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.

7. Offset lithography

8. Offset web press

9. 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

10. 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.

11. 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

12. 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.

13. Complementary Color Additive Colors Subtractive Colors (also the primary printing colors)

14. Additive & Subtractive RelationshipIt’s Complementary! A subtractive color filters out the primary color across from it (the complement) from white light. Place additive primaries at the points of the triangle. Subtractive primaries are placed between the two additives that combine to create them

15. 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.

16. 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.

17. Hue, Value and Saturation

19. 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.

20. Photographic Reproduction Half tone reproduction Preparing photographs for printing.

21. 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

22. 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

23. Knockout, mask, reverse & trap

24. 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 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 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

25. Sources