Viscosity printing

Adapted from Wikipedia: http://en.wikipedia.org/wiki/Viscosity_printing

Viscosity printing is a hand printmaking technique that involves all three of the basic printmaking processes: relief printmaking, intaglio printmaking, and planographic printmaking. It is an artist's printmaking technique, for making limited editions. It is a fairly slow process, and tends to have a degree of variability between prints. It involves the use of metal plates, as in the intaglio processes of etching, engraving, etc. Plates could be of copper, zinc, etc. Incisions are made on the plate to produce the imagery, commonly etched lines, patterns, and textures. Then the plate is inked. This could be done in one color throughout, or one could very carefully ink separate parts of the plate with separate colored inks. This is where the term viscosity comes into play. This first ink would be fairly dense — of a relatively high viscosity. This viscous ink is caused to fill the recesses of the incised lines on the etched plate. The surface is then carefully wiped clean, leaving the ink(s) in the recessed lines. This wiping is done either with the hand or with small pieces of a type of cloth called tarlatan. Next, a rubber roller is used to apply ink, of another color, and of a thinner viscosity, to the surface of the plate. This layer of ink does not mix with or interfere with the firstly applied ink because of the differing viscosities. Besides varying viscosities of ink, a second factor is employed — varying the hardness or softness of the rubber roller used to apply the second layer of ink. This can also have an effect on the miscibility or immiscibility of the two layers of ink. A third color can also be applied at this point. This third color is first spread on a glass plate. It would be rolled out very thinly using a rubber roller. This ink would be of the thinnest viscosity. (Viscosity is altered by the addition of substances such as linseed oil.) In order to apply this color the plate is turned upside down and pressed against the inked glass plate. This color only adheres to the highest points on the metal plate. A damp sheet of printing paper is then placed on the upright plate and passed through a printing press. Pressure causes the ink to transfer to the paper. All colors are of course printed at once. This is of a certain advantage, as in some other multi-color printing processes, an important concern is registering each succeeding color with the prior color(s). But beyond this technical distinction there are visually appealing qualities that can be coaxed out of this technique.