Color Lithographic Printing
Maury, 2010
Ink Terms:
Opacity
Litho inks are inherently semi-transparent.
Body
Consistency of ink (thick, thin, stiff, loose)
Tack
Stickiness of ink.
If ink is not tacky enough it won’t build up and stick to itself as you roll up. Too
much water when sponging can this and some additives.
Length
How far ink drags off spatula before breaking. Litho requires a ‘long’ ink
compared to intaglio or offset.
Viscosity
Resistance to flow. High=thick, Low=thin/runny.
Thixotropy
Stiff ink will loosen when worked with a spatula and become
stiff again when left to sit.
Mixing Inks:
Use a separate spatula for each ink color. DO NOT CONTAMINATE INKS!!!! Be sure to mix inks
thoroughly so there are no streaks.
Mix color like you would oil-based paints. For a light color, start with white and add color. A
complimentary color can be added to a color to dull it.
Use tap sheets to test colors (whether alone or overlapping colors).
Mix a small half dollar sized puddle for 5-10 prints.
Unused ink can be saved in aluminum foil or wax paper. Wax paper circles should be used to cover color
inks when done so they don’t dry out.
A ‘tint’ contains 50% or more white ink.
A ‘shade’ contains 15% or more black ink.
Modifying Inks:
Color inks can rarely be used right out of the can. The kind of image you are printing will dictate how you
need to modify your inks. Fine detail often requires a stiffer ink to prevent filling in (but not too stiff or not
enough ink will build up) while large/dark shapes and flats require a looser ink in order to lay down more
ink.
Cobalt Drier
Add to speed drying time of inks. Use only 2-3 drop for a half
dollar sized puddle.
Magnesium Carbonate
Stiffens ink and reduces tack. Do not add more than 25% mag to ink.
Alumina Hydrate
Same as mag but also gives ink a matte finish.
Varnish
Basic vehicle for ink pigments made from linseed oil. Comes in 00-10
(10 is most viscous/thick). Most inks use about a #5 varnish but adding
a lower or higher number changes body and adds grease.
Setswell
Softens ink, more buttery. Only add a pea sized amount to reduce roller
marks and reduces tack (good if printing on fibrous Asian papers).
Tint Base
Increases transparency. Overlapping inks should be 10% tint base.
Printing Color Inks:
Use ONLY rubber brayer or roller with inks. NEVER USE A LEATHER ROLLER!
Roll out thin, even layer on glass slab. Rubber roller holds less ink so you MAY need more passes.
Don’t over ink or image will fill in!
Clean brayer/roller with mineral spirits ONLY and put away in proper place.
Multiple inks on one image:
-if the inks do not overlap- the first ink should be dry before printing the
second ink, and so on for each color. All colors on an edition should be printed within 2-3 weeks
for best results.
-if the inks are meant to blend to create new colors then the first ink should be
slightly wet when printing the next ink and so on.
General Considerations:
Color Images on stone and aluminum plate require 3 etches (as opposed to 2 with black and white
images).
Printing papers can stretch with the printing of the first color and create registration problems. The paper
for an edition should be calendared (run through the press on sheet at a time) before printing to prestretch it. This is especially important with thicker papers.
Registration:
If printing multiple colors from multiple matrices, there are 2 main systems of registrations: T & Bar which
you are familiar with from beginning litho and punch registration which allows for very precise/accurate
registration. Both systems require the use of a mylar guide in order to accurately place registration.