CANCELED PLATE.
When the printing of a limited edition of prints has been completed, it is usual to deface the plates, stones, etc., to ensure that there is no possibility of their being reprinted. A cancellation impression is one that is taken to prove the cancellation.

CARBORUNDUM.
A very hard mixture consisting primarily of silicon carbide; it is used as an abrasive and, in powdered form, in a method of engraving invented by Henri Goetz. He used it to obtain a dotted effect by sprinkling it over a metal plate (usually duralumin) which was then pulled through a press, thereby causing the grains to penetrate the metal.

CARTOUCHE.
Ornamental design resembling the curves of a rolled-up parchment scroll. It is found at the base of old master engravings containing inscriptions (title, dedication, date, signature, etc.).

CHIAROSCURO or CHIAROSCURO WOODCUT. (See printmaking techniques)
1. In a general sense, chiaroscuro describes the method of using contrasted light and shade as a means of illuminating and giving form to a particular subject. 2. In a specific sense, it describes a particular woodcutting process (chiaroscuro woodcut) in which tone blocks (usually in lighter and darker tones of one color.) are overprinted and juxtaposed to obtain a colored print. The same technique can be applied to lithography: different stones are used for the varying tones.

CHINE COLLE.
Areas of thin colored tissue mounted on or glued to the surface of a print.

CHISEL.
A flat tool used in woodcutting. It has a bevelled edge and is either pushed manually, or knocked with a mallet, over large areas to be cut away, i.e. those between the edges of the design and the sides of the block.

CHROMOLITHOGRAPHY.
In a loose manner this can mean simply printing lithographs in color. The term was specifically applied to certain nineteenth-century color lithographs which were reproductive in intention and imitated the appearance of oil paintings. They were printed from a large number of stones, which demands a good technical skill.

CLEANING.
As used in painting conservation, refers to application of solvents and other liquids to remove discolored surface coatings, as well as to retouchings and restorations not part of the original work. In other contexts, it refers to the removal of dirt and coating from surfaces by a variety of liquid and/or dry techniques.

CLICHE-VERRE (GLASS PRINT). (see printmaking techniques)
A process of planographic printing. From the French term "clichoverre." The artist draws a design with a needle on a glass plate coated with an opaque ground from which positive photographic prints are made on sensitized paper as from an ordinary negative.

CLIPPING.
Reducing the margins of a print.

COLLAGRAPH.
The print resulting from a collage of materials glued together on a base and printed as a combined relief and intaglio plate.

COLLOTYPE.
Initially called albertype, after its principal inventor, this process consists in pouring a layer of gelatine mixed with potassium chromate over the surface of a zinc or glass plate which is then exposed to light to receive the image. The gelatine hardens in proportion to the amount of light received, the unexposed parts remaining soft and capable of retaining moisture, and the printing can therefore be done, lithographically: the plate is dampened with water and the ink is applied with a roller. It adheres to the surface in inverse proportion to the amount of moisture retained, the hard areas of gelatine printing the darkest. The reticulated grain of collotype is particularly good for reproducing watercolor, for which the process was much used during the latter part of the nineteenth century.

COLOR. BLOCK.
Color. blocks (or tone blocks) print the various colors in a color. or chiaroscuro woodcut. The key block prints the outline. See: chiaroscuro, color. printing.

COLOR PRINTING.
In woodcuts, color printing is done with several different color. Blocks which are overprinted. Chiaroscuro woodcuts are printed in various tones of one color. And for this reason cannot be classed as true color. prints. A more unusual method of color. Printing can be done from one assembled block; the various parts having been previously separated and inked with the different colors There are two different ways of intaglio color. Printing: with several plates, i.e. one for each color., which are overprinted juxtaposed next to each other; or with one plate which has been inked in different parts with separate colors applied with a brush or stumps of rag (a la poupee or "dolly"). Several stones are used in lithographic color. Printing, one or the other sometimes replaced by a zinc plate. Known as chromolithography (or chromo), it was a popular technique in the nineteenth century. Colors can be printed side by side, or overprinted, in screenprinting, by preparing the screen in such a way that a place is reserved for each color. without the various inks smudging. In letterpress, offset lithography and photogravure several blocks/plates are also used: there are three if the base colors, blue, red and yellow, are used (by overprinting different colors can be obtained), or four if grey or black is added to emphasize the dark areas. Printing with different colored blocks, plates or stones demands exact registration involving a careful concordance of the variously colored parts. Usually colors are printed from light to dark but often the blues are printed first. N.B. There is a difference between color. Prints and impressions taken from a single colorblock, plate or stone (other than brown or black). Neither must they be confused with handcolored prints.

CONSERVATION.
The restoration of works of art with the aim to correct damage caused by handling, excessive exposure to light, smoke, dust, humidity or aridity, and contact with liquid or any other destructive substance. Present methods allow cleaning and repair, provided that the print has not been subjected to irreversible alterations.

CONSERVATOR.
A person specially trained in the preventive care and maintenance as well as restoration of works of art and museum objects. The term restorer traditionally refers to a person trained in carrying out remedial or restorative treatments. In Francophone countries the term restaurateur covers both kinds of person; the term conservator referring to a curator or a keeper.

COPPER.
The most important metal used in engraving. It is supple to work, yet strong enough to endure the press, receptive to ink and wipes clean without leaving traces. It polishes well and is also sensitive to mordants. It does, however, tarnish quickly if left unprotected.

COPPER-FACING.
The application of a very thin layer of copper onto a metal plate by means of electrolysis. Zinc must initially be copper-faced if a steel-facing is to be applied.

COPY.
A print is a copy if the designer has taken the image from another artist.

CORROSIVE AGENTS.
Products used for cleaning and biting the various fabrics, papers, stones and metals used in printmaking are divided into three types: acids, alkalis and salts. Nitric acid is the most commonly used of the acids. It bites copper (c. 15 degrees Baume), zinc and steel (between 5 degrees 15 degrees Baume), in a rapid, shallow manner; it is also used for cleaning and for preparing the lithographic stone. Sulphuric acid is used for cleaning and biting steel. Hydrochloric acid attacks zinc and steel and in a diluted form is used for washing. Phosphoric acid is used for cleaning ferrous metals and aluminium as well as for preparing zinc and aluminium for the lithographic and offset techniques. Hydrofluoric acid attacks glass and ceramic. Acetic acid (vinegar) was formerly used frequently in the composition of etches. Of the alkalis, soda is the most commonly used: as a detergent for washing the screen, for cleaning metal plates, and for bleaching. It is used particularly on zinc, iron and aluminium, as well as on organic materials. Potash possesses approximately the same characteristics. Ammonia is used as a cleaning agent. The most frequently used of the salts is ferric chloride, a slow etch which penetrates in depth while preserving the form of the design. On account of these qualities it is much used in aquatint and photogravure.

COUTERPROOF.
An impression taken from a freshly printed sheet onto another piece of paper. It shows the design in the same direction as that on the plate, stone or block; the artist uses it for assessing corrections to be made.

COVERAGE.
The ability of an ink to cover and absorb into a surface as regards the amount required for printing. It is relative to the receptivity of the support to the ink.

CRACKS.
In grounds, paint layers, surface coatings (of paintings), the term designates a system of fissures that develop with the aging of the materials, or as a result of environmental action (expansion, contraction of the support), or a combination of both. There are various recognized systems of cracks, or craquelure, which result from both natural and environmental causes, and are characteristic too of the artist's technique and materials.

CRAYON.
Various types of crayon are used in printmaking. The greasy lithographic crayon is made with a natural grease or a chemical. A corrective crayon is used in lithography to remove lines or blemishes.