Printmaking Techniques
A brief guide to etching, engraving and lithographic processes
Introduction
Traditionally there have been three types of technique for producing prints.
Relief Printing - where a block of wood or metal plate is engraved or etched so that the image to be printed is left in relief and inked in a similar way to the printing of text from type.
Intaglio Printed - where the image is etched into the plate creating furrows into which the ink is deposited, generally leaving the surface of the plate free of ink.
Lithography - where the ink rests on the surface of a metal plate or stone, being held only on parts of the plate which have been treated with a special lithographic crayon or pencil.
Methods of Relief Printing
Typically printing of this type is from a woodcut or wood-engraving. The image is drawn directly onto the block and the parts which are to appear white (or to remain the colour of the paper) are cut away and what is not carved is inked and printed. The inking is usually done by a roller, and the ink is generally thick and sticky in order for it to adhere, temporarily, to the raised surface. The press used for the printing applies pressure vertically, to the whole of the plate and needs only comparitively small pressure.
A woodcut (utilising the oldest of the techniques) is made on a block of softwood (such as pear, apple, sycamore or beech), which has been sawn lengthwise with the grain and planed. Wood-engraving is essentially the same technique, but uses a harder wood (usually box) and is engraved on the end-grain of the wood. Almost all relief printing is carried out on wood - although relief printing from metal plates is also possible.
Methods of Intaglio Printing
There are many variations to this technique, but it is almost always carried out on a flat sheet of metal - quite often copper.
For line-engraving, the design is etched into the plate in the form of fine lines, using a tool called a graver, which is pushed across the plate to excavate the furrows. The technique called dry-point uses a sharp pointed instrument in a similar manner to a pencil, to scratch the chanels into the plate. The essential difference between the two techniques lies in the sharpness of the edges of the furrow. In line-engraving, the furrows have sharp, clean edges, which print as fine lines. This effect comes a result of the type of tool used, which removes the waste material neatly and cleanly from the furrow. In dry-point, the waste material is not removed so precisely, given the edges of the furrow a slightly soft look often described as a velvety tone.
In etching, the burrows in the plate are created by an acid. First the plate is coated with a wax, gum or resin which is resistant to the acid. The image is drawn onto the plate with an etching needle which needs only scrape away the coating to reveal the plate beneath, thus allowing it to be etched by the acid.
Other techniques such as mezotint, aquatint, stiple-engraving, crayon-engraving and chalk-engraving and others are, in essence, the same as etching, using an acid, but are designed to give tonal qualities rather than pure line effects.
Methods of Lithography or Surface Printing
There are various processes in which the print is taken from ink resting on the surface of a plate or stone, and a form of lithography is the foundation of most modern book and magazine printing.
In traditional lithography, the design is drawn onto a piece of flat stone using a form of grease - often in the form of a chalky substance. The stone is then soaked with water and then inked. The ink, being repellent to water, only adheres to the parts of the stone coated with the greasy chalk.