Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In a number of modern variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology, including circuit boards.
Aquatint is a variation in which particulate resin is evenly distributed on the plate, then heated to form a screen ground of uniform, but less than perfect, density. After etching, any exposed surface will result in a roughened (i.e., darkened) surface. Areas that are to be light in the final print are protected by varnishing between acid baths. Successive turns of varnishing and placing the plate in acid create areas of tone difficult or impossible to achieve by drawing through a wax ground.
Drypoint is a printmaking technique of the intaglio family, in which an image is incised into a plate (or "matrix") with a hard-pointed "needle" of sharp metal or diamond point. Traditionally the plate was copper, but now acetate, zinc, or plexiglas are also commonly used. Like etching, drypoint is easier for an artist trained in drawing to master than engraving, as the technique of using the needle is closer to using a pencil than the engraver's burin.
Woodcut is a relief printing technique in printmaking. An artist carves an image into the surface of a block of wood—typically with gouges—leaving the printing parts level with the surface while removing the non-printing parts. Areas that the artist cuts away carry no ink, while characters or images at surface level carry the ink to produce the print. The block is cut along the grain of the wood (unlike wood engraving where the block is cut in the end-grain). The surface is covered with ink by rolling over the surface with an ink-covered roller (brayer), leaving ink upon the flat surface but not in the non-printing areas. Multiple colors can be printed by keying the paper to a frame around the woodblocks (using a different block for each color). The art of carving the woodcut can be called "xylography", but this is rarely used in English for images alone, although that and "xylographic" are used in connection with blockbooks, which are small books containing text and images in the same block. Single-leaf woodcut is a term for a woodcut presented as a single image or print, as opposed to a book illustration.
A different technique is the Woodpoint. This is a flat technique in printmaking. HakMan the artist drills from small holes an image into the surface of a block of wood—leaving the printing parts level with the surface while removing the non-printing parts.
Monotyping is a type of printmaking made by drawing or painting on a smooth, non-absorbent surface. The surface, or matrix, was historically a copper etching plate, but in contemporary work it can vary from zinc or glass to acrylic glass. The image is then transferred onto a sheet of paper by pressing the two together, usually using a printing-press. Monotypes can also be created by inking an entire surface and then, using brushes or rags, removing ink to create a subtractive image, e.g. creating lights from a field of opaque colour. The inks used may be oil based or water based. With oil based inks, the paper may be dry, in which case the image has more contrast, or the paper may be damp, in which case the image has a 10 percent greater range of tones.
Monotyping produces a unique print, or monotype; most of the ink is removed during the initial pressing. Although subsequent reprintings are sometimes possible, they differ greatly from the first print and are generally considered inferior. These prints from the original plate are called "ghost prints." A print made by pressing a new print onto another surface, effectively making the print into a plate, is called a "cognate". Stencils, watercolor, solvents, brushes, and other tools are often used to embellish a monotype print. Monotypes can be spontaneously executed and with no previous sketch.
In printmaking, an edition is a number of prints struck from one plate, usually at the same time. This is the meaning covered by this article. This may be a limited edition, with a fixed number of impressions produced on the understanding that no further impressions (copies) will be produced later, or an open edition limited only by the number that can be sold or produced before the plate wears. Most modern artists produce only limited editions, normally signed by the artist in pencil, and numbered as say 17/25 to show the unique number of that impression and the total edition size.
Because of the variation in quality, lower-numbered prints in an edition are sometimes favored as superior, especially with older works where the image was struck until the plate wore out. However the numbering of impressions in fact may well not equate at all to the sequence in which they were printed, and may often be the reverse of it.
In later times, printmakers recognized the value of limiting the size of an edition and including the volume of the edition in the print number (e.g., "15/30" for the 15th print in an edition of 30). Tight controls on the process to limit or eliminate variation in quality have become the norm. In monotyping, a technique where only two impressions at most can be taken, prints may be numbered 1/1, or marked "unique". Artists usually print an edition much smaller than the plate allows, both for marketing reasons and to keep the edition comfortably within the lifespan of the plate. Specific steps may also be taken to strengthen the plate, such as electroplating intaglio images, which uses an electric process to put a very thin coat of a stronger metal onto a plate of a weaker metal.
The conventions for numbering prints are well-established, but other marks may indicate that a print has been made in addition to the numbered prints of an edition. Artist's proofs are marked "A. P." or "P/A", sometimes E. A. or E. d'A. (épreuve d'artiste); monoprints and uniquely hand-altered prints are marked "unique"; prints that are given to someone or are for some reason unsuitable for sale are marked "H. C." or "H/C", meaning "hors de commerce", not for sale. These are usually prints reserved for the publisher, like Artist's Proofs. The printer is also often allowed to retain some proof impressions; these are marked "P. P." Finally, a master image may be printed against which the members of the edition are compared for quality: these are marked as "bon à tirer" or "BAT" ("good to print" in French). In all, the number of the main edition can represent 50% or less of the total number of good impressions taken.
Professional artist printmakers will sometimes limit an edition to several artist's proof copies, including a "bon a tirer" print and then one unique copy designated as a "one-off" or "1/1" or "one/off".