A technical dictionary of printmaking, André Béguin.
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Diluting agent
A term that is often found in printing, engraving, and painting to designate the products used to lengthen and dilute inks, grounds, paints, and, more generally, all the products used in engraving. In chemical terminology the correct term is solvent*. In fact, the word solvent is applied to any liquid used to dissolve, lengthen, or dilute pigments, resins, oils, etc. Usually solvents are made of volatile products which, after drying, should not leave any traces.
In painting and printing one speaks of a carrying medium or a vehicle to describe the liquid added to the pigments to thin them out. In printing the thinner or reducer is the vehicle of the pigment [ ink].
A solvent must not be confused with a binder (in painting also called an agglutinant) whose function is to ensure the cohesion of the pigments and give them a particular final aspect (mat or shiny finish). Thus a water-based ink for silkscreening is made up of a pigment diluted in water and bound with natural or synthetic resins. The diluting agent used to thin this kind of ink is called a medium (an emulsion* of water and oil). The diluting agent or solvent used to clean tools once a job is finished, or when inks have dried up, is not necessarily the same as the solvent used in the ink. In this particular example the cleaning solvent used is acetone.
In printing silkscreen work artists often use diluting agents to remove ground, to thin or remove ink, to prepare silkscreens and to clean them.
Diluting agents are hardly ever used in engraving. In fact, the oily inks used in printing engravings are usually thinned with oil*. On the other hand, all silkscreen techniques make liberal use of diluting agents which are chosen in function of the ink and in function of the materials used to prepare the screen. White spirit is used for certain oil base inks, acetone is used for cellulose products, and emulsions are used for water base inks. Above and beyond these products there are also special products used to thin inks, to accellerate or slow down the drying process, to ground superficially, etc.
Under the heading solvent* the reader will find a table listing all of the various diluting agents used in printmaking.
[ serigraphy].
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