Lithographic Inks

There are several different classes of inks for offset lithography.

Petroleum Oil-based inks

1. Easy to work with, versatile, and dry well on coated and uncoated papers.
2. Oil base mixes well with pigments, both black and color, and tend to maintain true colors well.
3. Should not be left on press for more than six hours.
   • The press needs to be cleaned at close of each shift.
   • This is because added driers react with air and light to polymerize the solvent molecules and form a skin.

1. Were developed during the energy crisis when there was fear of a shortage of petroleum.
2. Environmentally friendly.
3. Utilize renewable resources.

1. Are also petroleum based but some cyclized rubber is added to improve rub resistance.
2. No driers are added.
   • Dry by absorption.
   • Do not oxidize in air or light.
3. Ink can be left in press for extended periods of time.
   • Do not form skin.
   • Doesn’t work well with coated paper.

1. Used with waterless litho plates such as used on the Heidelberg GTO-DI and Quickmaster-DI.
2. Works without fountain solution.
3. Ink adheres temporarily to oleophilic (image) area.

1. Magnetic inks used to print bank checks.
2. Fluorescent inks which are brightly colored and appear to glow as if illuminated from behind.
   • Absorb UV light and transmit it back as visible.
3. Metallic inks are very bright and take care to print.
   • Provide alternative spot colors.
4. Laser proof inks can withstand the extremely high temperatures produced by fuser in laser printers and photocopiers.
   • Used to produce letterheads and forms.
5. Overprint varnish is a clear ink which is printed over previously printed materials.
   • Can make the image shine.