Disclosed is a method of jet printing comprising receiving a liquid for printing, cooling the liquid, and jet printing the cooled liquid from an inkjet print head wherein by virtue of cooling the liquid, the viscosity of the liquid is increased and one or more operating characteristics of the jet printing is thereby improved. There is also disclosed jet printing apparatus comprising means to receive a liquid for printing, a jet print head and cooling means operable to cool the liquid prior to jet printing by the jet print head and thereby increase the viscosity of the liquid and improve one or more operating characteristics of the print head dependent on the viscosity of the liquid to be jet printed.
