Offset printing ink

Ink used for lithographic offset presses is a paste, rather than a fluid. That means it is thick and tacky.It is typically delivered in canisters. The image below shows Quattro offset printing inks from 4S Graphics.

CMYK offset lithography printing inks

Like all printing inks, offset lithography ink consists of three substances:

  • The ink vehicle is the fluid part of the ink that transports the pigment onto the substrate. This is typically an oil based material.
  • The pigment is the part of the ink that imparts gloss, color, texture, and other characteristics to the printed image. Pigments can be black, white (either opaque or transparent), and colored. The colored pigments are usually produced from either mineral sources or from derivatives of organic coal tar. Other materials such as metallic powders are used for specialty inks.
  • Various additives influence the characteristics of the ink. Driers speed up the drying of inks. Bodying agents increase the viscosity. Waxes help prevent printing defects like ink setoff and blocking and they increase the scuff resistance of the ink. Other materials are added to reduce the ink’s tack, improve its distribution on the printing plate, prevent oxidizing and enhance other properties of the ink.

Web offset inks tend to be more fluid and have less tack than sheetfed lithographic inks. Most offset inks dry rapidly without the need for additional equipment, but there are also inks optimized for infrared, ultraviolet or electron beam curing. All offset inks contains water-repellent materials, needed because offset lithography is based on the fact that oil and water do not mix.

Since offset presses can print on a wide variety of surfaces,  a large number of inks are available for the process. This YouTube movie shows how it’s manufactured.

More information on inks is available on this page.

4 February 2017

4 responses to “Offset printing ink”

  1. Uttam mishra says:

    Also i wanted to know as while printing we get variation in the shade in the final results on the substrate.
    Can something be done so as to get uniform print with uniform shade over ghe substrate eg. Film or paper or paperboard.
    Can you suggest some measures by which it can be controlled.

    • Laurens says:

      I am not the most suited to answer such a question because there may be a wide range of reasons why tints are not uniform and I have no practical knowledge of troubleshooting such problems. The plates might cause this if they are not uniformly exposed and developed. The inking mechanism on the press, its ink keys, non-uniform pressure or deformed rollers may all be reasons but how you determine the exact cause is beyond me. The question is better asked to your press vendor or posted on a specialist forum like printplanet.com.

  2. Uttam mishra says:

    Hello sir my name is uttam and i have gone through your page for printing ink for offsett.
    I had a doubt as why a repellent agent is used in this process eg. Water and oil.
    Why only ink cannot be used and print directly. Is it a compulsion to mix it with oil and water.
    Would be verry helpfull if you could help me with this doubt.

    Thank you.

    • Laurens says:

      In an offset printing press, a set of rollers is used to apply an even thin layer of ink on the paper. You need some agent to keep this from happening everywhere, otherwise you just print black pages. Usually that agent is water, but there is an alternative:
      In a waterless offset press special printing plates are used that have a silicone rubber coating. This coating is kept on the non-image parts and removed for all the image parts during the imaging and development process. That coating determines where the specially formulated inks are applied to the paper. Waterless offset has a number of advantages but also downsides: the two main ones are that you need actively cooled cylinders on the press and there is just one manufacturer of these types of plates. My daily newspaper is printed on a waterless KBA Cortina offset press (https://www.youtube.com/watch?v=u-2KKEfixzw). The Wikipedia page about waterless printing is at https://en.wikipedia.org/wiki/Waterless_printing

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