Q, R. (quartz - roughcast)

Quartz  SiO₂ - A hard, crystalline, transparent, often coloured mineral made of silicon dioxide. Quartz is one of the most common minerals in the earth's crust and occurs as grains (sand), masses (agate, bloodstone, chalcedony, jasper, carnelian, etc.) or crystals (rock crystal, amethyst, citrine, etc.). It can also be found as a major constituent of rocks such as granite. Quartz usually crystallises in hexagonal prisms or pyramids. It has been mined or gathered as a semiprecious stone since Paleolithic times. Sand is an additive in porcelain, brick, cement and mortar. Because of its hardness Mohs 7), quartz is also used as a cutting abrasive.
Synonyms: sand; agate; bloodstone; chalcedony; jasper; carnelian; sard; rock crystal (colourless); amethyst (purple); citrine (yellow); onyx; rose quartz (pink); smoky quartz (brown to black); yellow quartz; milky quartz (milk white); chrysoprase
Museum of Fine Arts, Boston (2000); English Heritage (2000); Trench (2000)

Quicklime -  Calcium oxide (CaO). See also lime. 
RS Means Building Glossary (undated)

Rangerís artificial stone - Patented in 1832 and named after its inventor, this artificial building stone combined a hydraulic lime with an aggregate such as beach shingle or broken flints and boiling water, which apparently produced a rapid set. See also : artificial stone
Trench (2000)

Rape-seed oil - A pale yellow vegetable oil expressed from the seeds of the Brassica campestris plant. Rapeseed oil is high in unsaturated acids, i.e., oleic, linoleic and erucic. This term is mentioned as small admixture of the polish composed of linseed oil, generally used in historic stucco in Krzeszòw, Poland.
Synonyms: Colza oil; canola
Wittenburg (1999); Museum of Fine Arts, Boston (2000)

Raw umber - A brown natural earth pigment that contains manganese dioxide and iron hydroxide.
Synonyms: umbra; terre d'ombre (Fr.); Pigment Brown 7
Museum of Fine Arts, Boston (2000)

Reactive silica material - Several types of materials that react at high temperatures with Portland cement or lime during autoclaving, including pulverized silica, natural pozzolan, and fly ash.
RS Means Building Glossary (undated)

Red ochre - Any of several naturally occurring red earth pigments. Red ochres contain hematite, red iron oxide, mixed with clay and vary widely in hue. They are stable pigments that have been used since ancient times.  See red iron oxide.
Synonyms: red ochre; red earth; iron oxide red; Indian red
Museum of Fine Arts, Boston (2000)

Render -  A general term for the weatherproof coat on the external walls of a building. 
English Heritage (2000)

Resin -  A solid or semisolid amorphous organic material. Resins are usually high molecular weight materials that fracture conchoidally. Natural resins are clear to translucent brown exudates obtained from trees or insects, such as copal, rosin, sandarac, mastic, dammar, or shellac. Most natural resins are soluble in alcohols, ethers and carbon disulphide, but insoluble in water. They are used in varnishes, and adhesives. Synthetic resins, or polymers, are formed by a chemical reaction between two or more substances. Examples are acrylics, alkyds, vinyls, epoxies, polyesters, polyolefins, phenolics, polystyrene and cellulose acetate. Synthetic resins are used in plastics, paints, and adhesives.
Museum of Fine Arts, Boston (2000)

Retarder - A chemical used to slow the drying rate of paint. Retarders were commonly used in the nineteenth century for wet-in-wet techniques. Examples of retarders for linseed oil paints are clove oil, spike oil, lavender oil, rosemary oil and poppy seed oil. Butyl lactate has been used as a retarder for industrial lacquers. 
Synonyms: Inhibitor
Museum of Fine Arts, Boston (2000)

Rich lime - A high quality calcium oxide with few impurities. When mixed with mortar, it improves the plasticity or workability of the mortar.  Rich lime is also used for fresco plastering.
Museum of Fine Arts, Boston (2000); RS Means Building Glossary (undated)

Rottenstone  -  A porous, lightweight, siliceous limestone used for polishing. This is mentioned as one of the polishes for stucco marble introduced in the twentieth century (along with tin ashes, polishing-red, polishing lime, sorrel salt and talcum).
RS Means Building Glossary (undated); Wittenburg (1999)

Roman cement  - Technically a quick setting hydraulic cement or lime, made by calcining a natural mixture of calcium carbonate and clay, such as argillaceous limestone, to a temperature below that required to sinter the material, but high enough to decarbonate the calcium carbonate, followed by grinding. The term has also been adapted to denote cement made from burning lumps of marl found in London clay, a technique adopted for C19th  building work. The term is so  named because its brownish colour resembles ancient Roman cements produced by use of lime-pozzolan mixtures, but is not intended to denote a relationship with Roman period 
English Heritage (2000); RS Means Building Glossary (undated)

Roughcast  -  A render including an aggregate of gravel or stone chipping thrown rather than trowelled onto an external wall. 
English Heritage (2000)
 
 

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