S. (silicone - synthetic resin)

Silicone - Any of a large group of semi-inorganic polymers based on siloxanes. Silicones were first discovered by F. Kipping in England in 1900, but were not commercially produced until 1943 by Dow Corning. Silicones can be liquids, gels, solids and elastomers. In general, they have excellent heat and chemical resistance and are water repellent. Silicones are used as adhesives, protective coatings and paints.
Synonyms: polysiloxane; organosiloxane
Museum of Fine Arts, Boston (2000)

Silicone resin -  A polymer that contains silicone, carbon and oxygen. Silicone resins were first discovered by F. Kipping in England in 1900, but were not commercially produced until 1943 by Dow Corning. Silicone resins are made by the room-temperature vulcanisation (RTV) of silicone oils. They can cure either with moisture in the air (single-component system) or by the addition of a peroxide catalyst (two-component system). Once cured, silicone resins are chemically inert and can exist as elastomers and resins (both thermosetting and thermoplastic). They function over a wide temperature range, are water repellent and have very poor adhesion. Silicones are used as sealants, moulding compounds and varnishes.
Synonyms: polysiloxane; organosiloxane; SI; Silastic
Museum of Fine Arts, Boston (2000)

Silicious Concrete Stone - A brand name used by the Pacific Stone and Concrete Company (San Francisco) for an artificial stone made with water glass. Silicious Concrete Stone was made by a process patented by F. Ransome in 1856. In this process, water glass (sodium silicate) is mixed with sand (and gravel, flint, chalk, or limestone) in an aqueous solution of caustic soda. Then this alkaline solution is mixed with calcium chloride to form an insoluble silicate stone.
Synonyms: cast stone; imitation stone; artificial stone
Museum of Fine Arts, Boston (2000)

Size - Animal glue dissolved in water. Collagen is extracted from the skin of animals such as rabbits or sheep by boiling it for many hours, and is usually stored as leaves of gelatin or powder. It diluted form it is used to seal porous surfaces. Size has been a painting medium since pre-classical times, usually for wall paintings e.g. distemper. Examples are rosin, glue, gelatin, casein, gums, starch and modified cellulose.
Synonyms: Sizing
Trench (2000); Museum of Fine Arts, Boston (2000)

Skin glue - An impure gelatin prepared from the skins of animals (Gettens and Stout 1966). It is mentioned as one of the organic additives used for stucco marble preparation according to literature. 
Synonyms: animal glue; hide glue; nikawa
Gettens and Stout (1966);  Museum of Fine Arts, Boston (2000); Wittenburg (1999)

Slag cement -  A type of hydraulic cement. Slag cement is made by mixing Portland cement (calcium silicate), powdered blast furnace slag and lime. It is also called artificial Pozzolana cement.
Synonyms: artificial Pozzolana cement
Museum of Fine Arts, Boston (2000)

Slaked lime - Hydrated lime prepared by soaking quicklime in water. See calcium hydroxide.
Synonyms: calcium hydroxide; hydrated lime
Museum of Fine Arts, Boston (2000)

Slaking - The reaction of quicklime with water. During the process, hydroxides of calcium (and magnesium) are formed by the action of water on the oxides of the quicklime. Traditionally, this process was carried out in pits and the slaked lime was left to mature for several months, or even years. 
Ashurst (1983)

Slap-dash - See slab plastering
Synonyms: slap dash; slab plastering
Museum of Fine Arts, Boston (2000)

Slurry  - Cement/water mix often used as covering. Use this for entries including slurrying and slurried. 
English Heritage (2000)

Smalt   K, Al, Co silicate -  A finely ground blue potassium glass containing small amounts of cobalt oxide. It was used in European paintings from the 15th  century to the early 19th  century when it was replaced by Prussian blue. The composition of smalt varies with manufacture. It is prepared by fusing cobalt oxide with potassium carbonate and silica. Smalt has been used as a blue colourant in paints. It is also listed among the pigments used for colouring stucco marble in the nineteenth and twentieth century.
Synonyms: azure blue; Dumont blue; Hungary blue; Saxon blue; eschel; zaffre; zaffera; royal blue; blue glass; starch blue; king's blue; bleu de smalte (Fr.); couleur; Streublau (Ger.) Smalte (Ger.); Zafferblau (Ger.); azzurro di smalto (It.); smaltino (It.); esmalte (Sp.); hana konjo (Jap.)
Wittenburg (1999); Museum of Fine Arts, Boston (2000)

Soap - A water-dispersible cleansing product. Soaps are produced by the saponification reaction of long chain fatty acids, such as found in oils and fats, with an alkali, such as sodium hydroxide or lye. Soaps made from animal fat and wood ashes have been used since antiquity. Soap is listed as a substance for coating and polishing the surface of stucco marble in the seventeenth and eighteenth century (soap solutions) and in the nineteenth century (soap water).
Wittenburg (1999); Museum of Fine Arts, Boston (2000)

Solvent - Any liquid which dissolves another compound (solute) to form a homogeneous solution. Solvents are characterised by their polarity, evaporation rate and composition. Water is the most common solvent. It is strongly polar. Organic solvents, such as acetone, ethanol, turpentine and carbon disulphide are less polar. Hydrocarbon solvents such as hexane and mineral spirits are non-polar. Many solvents are volatile and some are flammable and toxic.
Museum of Fine Arts, Boston (2000)

Sorrel salt - potassium binoxalate KHC₂O₄ - + H₂O.   White, slightly hygroscopic crystals. This is mentioned as one of the polishes for stucco marble introduced in the twentieth century (along with tin ashes, rottenstone polishing-red, polishing lime, and talcum).
Synonyms: potassium acid oxalate; potassium hydrogen oxalate; salt of lemon (incorrect)
Museum of Fine Arts, Boston (2000); Wittenburg (1999)

Spence's plaster - A type of gypsum cement. Spence's plaster is made with finely powdered gypsum mixed with Portland cement. It also contains aluminium sulphate and sand. It is a hard, strong, durable finish plaster.
Synonyms: gypsum cement
Museum of Fine Arts, Boston (2000)

Stand oil - A pale, thick, concentrated form of linseed oil. Stand oil is prepared by anaerobically heating linseed oil to about 300°C. This allows the oil to partially polymerise without any oxidation occurring. Anaerobic conditions are obtained using a vacuum or carbon dioxide atmosphere. Stand oil was likely developed by the Dutch in the 19th century. Stand oil dries more slowly and yellows less than untreated linseed oil. It forms a tough, flexible film that is resistant to weathering. Stand oils have been used in varnishes, glazes and as a high viscosity additive to other paint media. Half oil is half stand oil and half oil of turpentine.
Synonyms: English oil varnish; Standöle (Ger.); half oil; standoil
Museum of Fine Arts, Boston (2000)

Starch -  Carbohydrate granules of varying size obtained from roots, bulbs and seeds of most plants. Starch is primarily obtained from rice, wheat, corn, potatoes, cassava (tapioca), sago and arrowroot. The white, powdery granules range in size from 3-150 micrometers. Starch is a mixture of the soluble straight-chain amylose molecules and the insoluble, branched-chain amylopectin molecules. When starch is heated, the granules swell and form a thick, tacky jelly upon cooling. Starchy adhesives have been used since at least 3500 BCE in Egypt. Starch is sensitive to moisture and biodegradation. Paste films become brittle with age. Dextrin is prepared from starch by baking it at 200-250*C until the material becomes completely soluble in cool water. Soluble starch can also be made by hydrolysing the granules with dilute hydrochloric acid followed by neutralisation with an alkali. Soluble starch has been used  as a binder in watercolour paints.
Synonyms: fecula; wheat; corn; rice; potato; tapioca; arrowroot; sago palm; amylum
Museum of Fine Arts, Boston (2000)

Steading's compound - Dicalcium aluminate monosilicate-8-hydrate, a compound that has been found in reacted lime-pozzolan and cement-pozzolan mixtures. 
RS Means Building Glossary (undated)

Sticker - An additive that increases the strength with which water- soluble materials attach to solid surfaces. 
RS Means Building Glossary (undated)

Stone lime - Lime prepared by calcining limestone or marble in a kiln (Bucher 1996).
Museum of Fine Arts, Boston (2000)

Stucco -  A term used broadly to describe all forms of decorative plasterwork, although it refers specifically to relief decoration modelled and moulded in lime and aggregate (often marble dust) mixes, with or without the addition of gypsum plaster. These mixes can take fine detail and be worked to a hard, smooth finish. The word also has regional variations : in Italy it is used to describe a range of pliable materials which can be shaped; in Britain and the USA it can refer also to cement and sand renders, which from the late 18th century were used on building faces to imitate stonework.  Stucco has been used since ancient times. Still widely used throughout the world, it is one of the most common of traditional building materials. Historically, the term "plaster" has often been interchangeable with "stucco"; the term is still favoured by many, particularly when referring to the traditional lime-based coating. Interior stucco was made usually made with gypsum, marble dust and glue. It was often moulded into ornamental shapes and polished to a marble-like finish. During the 17th and 18th centuries, elaborate painted figures and ornaments were made with stucco. By the nineteenth century "stucco," although originally denoting fine interior ornamental plasterwork, had gained wide acceptance in the United States to describe exterior plastering. "Render" and "rendering" are also terms used to describe stucco, especially in Great Britain. Exterior stucco is usually composed of cement, sand and hydrated lime, or lime and sand or brick dust. It is mixed with water and applied wet. Occasionally, pebbles or other aggregate are added for texture. Examples include pebble dash, rough cast, tabby and spatter dash. Other historic treatments and coatings related to stucco in that they consist at least in part of a similarly plastic or malleable material include: parging and pargeting, wattle and daub, "cob" or chalk mud, pise de terre, rammed earth, briquete entre poteaux or bousillage, half-timbering, and adobe. All of these are regional variations on traditional mixtures of mud, clay, lime, chalk, cement, gravel or straw. Many are still used today. 
Trench (2000); Grimmer (2001); Museum of Fine Arts, Boston (2000); English Heritage (2000)

Stucco lustro - A form of imitation marble (sometimes called stucco lucido) used from the 17th century, in which a thin layer of lime or gypsum plaster is applied over a scored support of lime. While the plaster is still wet, pigment is scattered on the surface and then dragged across it with a brush or comb to suggest veining. The surface is then polished to a high sheen with a hot iron. Although this method does not make as faithful a reproduction of marble as scagliola, it has the advantage of being quicker to produce and does not require the use of scraping tools, which are difficult to employ on curved surfaces. It is mentioned as one of the historic techniques for decorating architectural surfaces.
Trench (2000); Wittenburg (1999)

Stucco marble - The Italian definition of stucco marble is ìscagliola ad imitazione del marmoî, meaning literally ìscagliola with marble imitationî. It has a complex composition, and its many variations are a function of period, region and, probably, individual manufacturing practices. The main ingredients of stucco marble are gypsum (sometimes with the addition of lime), perhaps with additives (e.g. alum, borax), water, a binding medium containing protein and/or organic pigments and an organic surface coating to give it the characteristic high gloss. There are two different ways of colouring the stucco: addition of pigments to the glue (a method to obtain a uniformly dyed mass), or addition of dry pigments to the fresh stucco paste.  To obtain the effect of a natural stone, small balls of paste in different colours are formed, layered, kneaded, and cut transversely.  The ground for stucco marble is usually masonry, with plaster covered by the usual adjustment layer.  The stucco marble layer is attached with glue while damp and pressed with a metal trowel (brass, copper or steel). The characteristic of the stucco marble technique is the special treatment of the gypsum mass that hardens when dry because of the addition of various substances.  The paste has to be plastic enough to allow kneading and set hard enough to be polished and smoothed.  The goal is to obtain on the one hand the highest degree of hardness of the stucco paste, and on the other, to retard the setting of the gypsum.  Therefore, the primary requirement is the right calcination (burning) of the gypsum.  Once the desired quality of gypsum powder is obtained, the next step is the setting in water: substances retarding the setting and facilitating hardening are added to water. The smoothness and glossiness typical of marble is obtained through grinding and polishing.  The surface must be very well smoothed until it becomes hard.  After scraping with a knife or a wooden spatula, holes or pores are filled with a mixture of gypsum and glue if necessary. After each grinding step this procedure must be repeated.  The grinding is done with the use of a lot of water and various grinding stones.  For additional gloss, oil is applied to the surface.  When it is all smoothed, it must be left to dry and then rubbed down with a linen cloth.  Further wax treatment is often added: in case, solid wax (or wax in turpentine) is applied to the surface, which is then buffed with a linen cloth. Stucco marble is frequently confused with stucco lustro which is based on lime plaster and belongs primarily to the fresco technique. Stucco marble was used to imitate marble in wall decorations, from the seventeenth to the twentieth century in Europe. 
Wittenburg (1999)

Stucco mesh -  A type of wire cloth used as a support for stucco. Stucco mesh is typically made from 17 gauge wire twisted to form 1.5 inch hexagonal openings (Bucher 1996).
Synonyms: stucco netting
Bucher (1996); Museum of Fine Arts, Boston (2000)

Sugar - A photosynthesis product in plants. Sugar is an important source of metabolic energy in foods and its formation in plants is an essential factor in the life process. Sugar is a small carbohydrate composed of one, two or more saccharose groups. The chief monosaccharides are glucose (dextrose) and fructose (levulose). Some primary disaccharides are sucrose (from cane or beet sugar); lactose (from milk); maltose (from starch); and cellobiose (from cellulose). Table sugar is primarily composed of sucrose.
Museum of Fine Arts, Boston (2000)

Support - The inner structural material on which an exterior finish (i.e., paint, veneer, etc.) is applied. In architecture, supports maintain the primary weight-bearing load and are usually constructed from wood or steel.
Museum of Fine Arts, Boston (2000)

Surfactant -  A commonly used shortened form of surface active agent. Surfactants are compounds which reduce interfacial tension at the boundaries between gases, liquids and solid. They promote wetting and penetration of liquids into solids and act as a detergent, emulsifier, or dispersing agent. These include additives to a concrete mix to reduce the surface tension of the mixing water and facilitate wetting, penetrating, emulsifying, dispersing, solubilising, foaming, and frothing. Non-ionic surfactants, such as ethoxylated alkyl alcohols and akyl phenols, have been used as emulsifiers in acrylic emulsion paints. 
Synonyms: surface active agent; wetting agent; detergent; penetrant; emulsifier; penetrant; dispersing agent
Museum of Fine Arts, Boston (2000); RS Means Building Glossary (undated)

Synthetic resin - Synthetic resins or polymers are becoming increasingly available and have applications in nearly every aspect of life. Their wide range of properties and forms provide films, coatings, adhesives, paint media, fabrications, cushions and protectors.
Museum of Fine Arts, Boston (2000)
 
 

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