C. (chert - cyanoacrylate)

Chert - An impure, flintlike rock, usually dark in color. Some of its common impurities react with cement, making its use as an aggregate undesirable for certain applications. 
RS Means Building Glossary (undated)

Chrome green -  A pigment mixture prepared with chrome yellow (lead chromate) and Prussian blue. Chrome green has been used since the early 19th century, primarily in house paints and industrial products.
Synonyms: cinnabar green; green vermilion; Victoria green; Prussian green; bronze green; Milori green; Pigment Green 15; Brunswick green; nitrate green; royal green; zinnober green; oil green
Museum of Fine Arts, Boston (2000)

Chromic oxide - A dull, olive-green colour pigment. Anhydrous, opaque chrome oxide green was first made in 1809 by Vauquelin and was listed as an artists pigment in the 1840 Winsor and Newton catalogue (Newman 1997). It is opaque, lightfast, and durable with excellent resistance to chemicals and heat. Chromic oxide has limited use in paints because of its dull colour. Chromium oxide is also used as an abrasive.
Synonyms: chrome oxide; opaque chromium oxide; chromium oxide green opaque; chrome sesquioxide; Anadonis green; ultramarine green; Pigment Green 17; leaf green; oil green; green rouge; chromia; --not to be confused with chrome green (lead chromate and Prussian blue) and emerald green (copper acetoarsenite); Schnitzer's green
Museum of Fine Arts, Boston (2000); Newman (1997)

Chrysocolla  CuSiO₃-nH₂O  -  A sky blue mineral composed of hydrated copper silicate. Chrysocolla is a secondary copper ore that has also been used as a gemstone and a blue-green pigment. It has been gathered or mined as a semiprecious stone since 3000 BCE. Chrysocolla is mined in Cornwall, Cumberland, Congo, Chile, and the U.S. (Pennsylvania, Arizona, New Mexico and Utah). The translucent to opaque stone is sky-blue in its natural state, but appears green when ground into a fine powder. Chrysocolla has been found as a pigment in wall painting at Kizil in Turkistan and in Twelfth Dynasty Egyptian tombs (Gettens and Stout 1966). In the 16th and 17th centuries, it was used as a watercolour pigment called cedar green. Chrysocolla is stable to light but is decomposed by acids, alkalis and heat.
Synonyms: cedar green; copper silicate
Gettens and Stout (1966); Museum of Fine Arts, Boston (2000)

Cinnabar HgS   - A soft, dense, red, native ore composed of mercuric sulphide. Cinnabar is widely distributed around the world and is most often found in veins near volcanic rocks or hot springs. It has been mined from the Spanish cliffs near Almadén for over 2000 years. Other deposits are found in Italy (Iudrio), Germany, Austria, Yugoslavia, China (Hunan, Kweichow), Turkestan, Mexico, Peru (Huancavelica) and the United States (Texas, California). Cinnabar was finely ground for use as an artist pigment since antiquity. Red mercuric sulphide has been made synthetically since at least the 8th  century in Europe and possibly earlier in China. Synthetic mercuric sulphide is called vermilion. Due to impurities, vermilion was favoured over ground cinnabar as a red pigment. When exposed to ultraviolet light, mercuric sulphide darkens as a portion changes from its normal red crystalline form to a black isomorph. This can result in splotchy discolorations. It is listed among the pigments and dyes used for colouring stucco marble in the seventeenth and eighteenth century.
Synonyms: vermilion (synthetic pigment); Chinese vermilion; English vermilion; Pigment Red 106; CI 77766; red mercuric sulphide; red sulphuretted oxide of mercury; liver ore; Zinnober (Ger.); cinabrio (Sp.); cinabre (Fr.); cinabro (It.); shinsha (Jap.); tan-sha (Chin.)
Wittenburg (1999);  Museum of Fine Arts, Boston (2000)

Clay - A naturally occurring earthy mineral that is plastic when wet but becomes permanently hard when heated. Clay is composed of hydrated aluminium silicates, such as kaolinite, illite, palygorskite, attapulgite, bentonite and montmorillonite. Small amounts of other minerals can change the colour (white, yellow, brown or red) and texture of the clays. When pure, clay is a fine, white, amorphous powder which becomes plastic when water is added. When heated to high temperatures, clays become hard due to the loss of water and are used to make pottery, porcelain and bricks. Clay is also used as a filler and whiting in paints and grounds.
Synonyms: clays; China clay; kaolin; porcelain clay; tonerde; fuller's earth; white bole; pipe clay; Bouvigal white; Rouen white; Spanish white; Troy white; feldspar
Museum of Fine Arts, Boston (2000)

Clay-lump -  Lumps of clay, tempered with straw or reed and dried in the sun, usually about 6î x 9î x 1í3î.
Powys (1929, reprinted 1981)

Clay mortar - See mud mortar
Museum of Fine Arts, Boston (2000)

Coade Stone - A brand name for a cast stone made from fired clay. Coade Stone was developed by Eleanor and George Coade in England and manufactured from 1769 to 1843. The formula, which was lost following closure of the factory, has only been deduced from recent analysis and experimentation. Analysis indicates the raw materials were ball clay from Dorset or Devon with the addition of 5-10% flint, 5-10% quartz sand, at least 10% grog and about 10% soda-lime-silica glass. The material was fired at temperatures between 1100°C and 1150°C over a four-day period, producing a hard, partially vitrified and durable material. Minimal shrinkage and distortion in the kiln, owing to the presence of the pre-fired grog, contributed to the materialís commercial success. These terracotta cast stones were used for interior and exterior ornamental elements. Coade Stone is acid resistant and weathers well. It was used for statues, tombs, balustrades, vases, pillars and decorative architectural elements. 
Synonyms: terracotta; imitation stone; architectural terra cotta; artificial stone
Freestone et al (1984); Trench (2000); Museum of Fine Arts, Boston (2000)

Coarse stuff -  A coarse, fibre-filled, base coat for plaster. Coarse stuff contains lime paste mixed with sand and hair. Other fibre fillers may be used such as sisal, jute, wood or asbestos. This coarse plaster mixture was used for the base plaster layers applied to the metal or wooden lathes. It was covered with a smooth finish plaster.
Synonyms: fibre plaster; scratch coat; brown coat
Museum of Fine Arts, Boston (2000)

Coating - A protective layer placed over the surface of another material (substrate). Many type of materials are used for coatings. Examples are paints, varnishes and polymer films. Coatings may be painted, sprayed or vapour deposited onto the substrate.
Museum of Fine Arts, Boston (2000)

Cob  (Clob) - Walls composed of clay, earth, straw, lime and sand, mixed with water. Wet clay or chalk is tempered by the tread of horses with straw or reed. It is constructed without shutters in layers upon a stone or brick plinth. It is lifted wet on to walls, the surface is trimmed in position as it hardens. Shrinkage is considerable. It is usually covered with protective limewash or plastered. 
Powys (1929, reprinted 1981); English Heritage (2000)

Cobalt blue - A clear blue to blue-green pigment. Cobalt blue is composed of a double oxide of cobalt and aluminium that is also called cobaltous aluminate. Cobalt blue is resistant to weathering, sunlight, acids and alkalis. Though possibly discovered earlier, the process for making cobalt blue by heating cobalt phosphate with alumina was first published by L.J.Thénard in France in 1802. Leithner discovered a process for making cobalt blue from cobalt arsenate and alumina. By the early 19th century, cobalt blue was sold as an artists pigment as a replacement for smalt. In recent years, the cobalt blue hue has been imitated using mixtures of ultramarine and phthalocyanine.
Synonyms: Thenard's blue; Pigment Blue 28; CI 77346; cobalt ultramarine; cobaltous aluminate; king's blue; Olympia blue; Vienna blue; Vienna ultramarine; Leyden blue; Hungary blue; azure cobalt; Gahn's blue; Leithner blue; new blue; Kobaltblau (Ger.); bleu de Thénard (Fr.)
Museum of Fine Arts, Boston (2000)

Cobalt violet - A general name for several violet coloured cobalt pigments. First developed in the early 19th century, cobalt violet was the primary permanent violet pigment available. Cobalt violets range from deep to pale shades with either a pink or blue hue. The first cobalt violets used were composed of cobalt arsenate. This highly toxic compound is now rarely used. Instead most current cobalt violets are non-toxic and are made from either cobalt phosphate, or cobalt ammonium phosphate. Cobalt violets are used in paints. 
Synonyms: cobalt arsenate; cobalt phosphate; cobalt ammonium phosphate
Museum of Fine Arts, Boston (2000)

Cobble -  Naturally occurring glacial rock fragments (diameter 64-256mm) larger than pebble and smaller than boulder. 
English Heritage (2000)

Collagen - The protein which makes up the main three-dimensional fibrous network in a skin. It is found in stucco marble (Krzeszòw, Poland ? late Baroque), which indicates that the glue used for the preparation of the stucco mass was obtained from collagen-containing materials, like fish, animal bones or skins.
Trench (2000); Wittenburg (1999)

Colorant -  Any compound, such as a dye or pigment, that gives colour to another material. Colorant may occur naturally in a material (colours in flowers), may be added as part of a mixture (pigments in paint) or may be applied to the surface (dyes on a fibre).
Museum of Fine Arts, Boston (2000)

Coloured cement - A decorative cement prepared by adding a limeproof pigment to the concrete mixture.
Museum of Fine Arts, Boston (2000)

Common lime - Hydrated lime or quick lime used in plaster or mortar. 
RS Means Building Glossary (undated)

Concrete - A hard, strong construction material cured from a semi-fluid matrix of water, sand, and aggregates with cement and/or lime. Several types of aggregate are used such as crushed stone, slag, cinders or gravel. Ancient Romans developed pozzolana cement about the 3rd  century BCE. Modern concretes use various cements such as Portland or hydraulic. Concrete is durable and relatively inexpensive. It is used for building. Concrete is strong in compression but weak in tension so it is often reinforced with steel bars or wire netting. Once a concrete mixture is stirred with water and poured into a mould, it should be allowed to cure slowly over about a week. Stresses, such as vibration, freezing and rapid drying, will diminish the strength and durability of the concrete. As it ages, concrete is subject to erosion, spalling and pollution. Poor mixing can cause erosion. Spalling can be due to freeze thaw-cycles of moisture and ice, salt crystallisation, or corrosion of steel reinforcements. Acid rain can deplete the natural alkaline reserve of fresh concrete.  See also cement.
Synonyms: Breton
Museum of Fine Arts, Boston (2000)

Concrete plaster - See bond plaster
Museum of Fine Arts, Boston (2000)

Consolidant - A substance used to strengthen and solidify another material. A consolidant is infused into the interstices of a porous, friable or deteriorated material, such as stone, paint or wood. The consolidant hardens within the pores to stabilise the structural integrity of the piece. Examples of materials used as consolidants are: epoxies, acrylics, silicates and polyethylene glycols.
Museum of Fine Arts, Boston (2000)

Copal - A general name given to a large variety of hard, natural resins obtained directly from trees such as Trachylobium hornemannianum and Hymenaea courbaril. Copals are also obtained as fossil resins from Zaire and Zanzibar. The fossil resins are very hard and almost completely insoluble. Copals are diterpenoid resins that contain communic acids, communol, resene and volatile oil. They range in colour from colourless to a bright yellow-brown. The hardest copal resin is Zanzibar. Sierra Leone, Kauri, and Congo are of medium hardness. Manila, and Borneo are soft copals. The oldest resins are the hardest. Copal resins may be purchased as large lumps or small tears. Copal resins were used as oil varnishes in the 18th  and 19th  centuries but they tend to darken and become insoluble with age. They also have been used in commercial varnishes.
Synonyms: Zanzibar; Demerara; Benguela; Sierra Leone; Mozambique; red Angola; white Angola; Congo; kauri; Manila; Pontianak; Madagascar; Accra; Loango; Gaboon; Borneo; Singapore; South American; Cochin; Brazilian; Benin, swamp gum; anime; cowrie
Museum of Fine Arts, Boston (2000)

Copper vitriol - The term vitriol, now obsolete, was formerly applied to a number of metal sulphates because of their glassy appearance. In the twentieth century, coloration of stucco marble was obtained by chemical reaction involving copper vitriol, iron vitriol, gypsum and alum with lime.  See also : vitriol.
Hampel and Hawley (1982); Wittenburg (1999)

Crude beeswax -  See beeswax
Synonyms: virgin wax
Museum of Fine Arts, Boston (2000)

CS -   cast stone 
RS Means Building Glossary (undated)

Cyanoacrylate - A thermoplastic polymer commonly used as a fast-setting, strong adhesive. The first cyanoacrylate adhesive was made in 1941, but not marketed till 1958 as Eastman 910®. Cyanoacrylate adhesives are based on ethyl-2-cyanoacrylate polymers. Most commercial formulations also contain stabilisers, thickeners and catalysts. The glues set rapidly (5 seconds - 3 minutes) upon exposure to ultraviolet radiation or moisture. When cured, they form an extremely strong bond that is fairly insoluble. Cyanoacrylate glues have been used for gluing glass, ceramics and other hard materials. Some cyanoacrylate glues may lose adhesive strength with time. Ultraviolet light and contact with alkaline materials (glass and some stones) will accelerate the degradation process.
Synonyms: super glue; Super Glue GelÖ [Loctite]; Krazy® glue [Borden]; Super Attack [Loctite]; Zap; Eastman 910® [Eastman Chemical]; ELFY® super glue; ethyl cyanoacrylate
Museum of Fine Arts, Boston (2000)
 
 

Bibliography            Index