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Varnishes - The part of the ink in which the other materials (pigments, driers, waxes and modifiers) are dissolved or suspended. Drying oil varnishes are made by heating linseed, tung, castor, tall, soybean or safflower oil with alkyd, urethane and phenolic resins. These oils are converted to varnishes by heating. Alkyd Varnishes - Used for lithographic inks. Resin is made by reacting phthalic anhydride with glycerol.

Each phthalic anhydride can react with two glycerols and each glycerol can react with three anhydrides so that a cross-linked network is formed. This polymer is then reacted with the drying oil to modify it. (Soya oil may be used by heating unmodified).

Urethane varnishes are produced by reacting an isocyanate with an alcohol.

R-N=C=O + HOCH₂R' -> R-NH-COCH₂R'

An example with Toluene diisocyanate and trimethylol propane is shown in the book. This forms a network similar to the alkyd varnish. Phenolic Varnishes are formed from a phenol and formaldehyde.

A linear polymer is formed as opposed to network polymers above. A network can be obtained by reacting with rosin esters. For example, pentaerythritol (C(CH₂OH)₄) can be used to crosslink phenolic varnishes.

Soybean oil is used in sheetfed offset to replace up to 20% of more expensive vehicles. Heatset inks - specially fractionated hydrocarbon which evaporates in high velocity hot air dryers. Used for web offset with the soft hot ink film being set by cooling on a chill roll. UV curable inks are now used extensively in Flexo printing. They are also used for gravure, but are seldom used in web offset. UV curable inks contain low molecular weight oligomers, which cure upon irradiation with UV light in the presence of a photoinitiator.

The solvent/diluent is usually a hydrocarbon oil or vegetable oil. High boiling hydrocarbon solvents (heatset oils) are used in heatset inks for web offset printing. Heatset oils are dried rapidly by passing the web through a hot air dryer. Most of heatset oil evaporates in dryer. Quickset inks for sheetfed offset contain resin-solvent varnishes with some free oil. These set rapidly by adsorption of some of the oil onto the paper.

Cosolvent inks - A mixture of two or more solvents may be more powerful. May consist of an alcohol or glycol added to a hydrocarbon. Modifiers or Additives - Small amounts of materials added to inks. Include antiskinning agents, wax compounds, reducers and solvents. Antiskinning agents prevent skin formation in ink fountain and rollers. A good antiskinning agent increases skinning time without increasing drying time.

Methyl ethyl ketoxime, butylated hydroxy toluene (BHT) and hydroquinone are used as anti skinning agents. Waxes improve slip, mar-resistance and water repellency. May decrease gloss or interfere with dry trapping. Waxes used include polyethylene wax, poly-tetraflouroethylene, fatty acid amides and a variety of hydrocarbon waxes including paraffin. Petroleum solvents are sometimes added to reduce tack.