Glossary

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Abrasive / Sand Paper

Paper sheets are covered with miniscule natural or artificial crystal fragments that depending on their size give the sheet a grade of roughness. The higher the number, the finer the grade resulting in a better finish. The number can go as high as 1800/2000. It is used to smooth or clean surfaces.

Acid

 

The word "acid" comes from the Latin acidus meaning "sour," but in chemistry the term acid has a more specific meaning. There are some common ways to define an acid:

  • Arrhenius: According to this definition developed by the Swedish chemist Svante Arrhenius, an acid is a substance that increases the concentration of hydrogen ions (H+), which are carried as hydronium ions (H3O+) when dissolved in water, while bases are substances that increase the concentration of hydroxide ions (OH-). This definition limits acids and bases to substances that can dissolve in water. Around 1800, many French chemists, including Antoine Lavoisier, incorrectly believed that all acids contained oxygen. Indeed the modern German word for oxygen is Sauerstoff (lit. sour substance), as are the Afrikaans and Dutch words for oxygen suurstof and zuurstof respectively, with the same meaning. English chemists, including Sir Humphry Davy, at the same time believed all acids contained hydrogen. Arrhenius used this belief to develop this definition of acid.
     
  • Brønsted-Lowry: According to this definition, an acid is a proton (hydrogen nucleus) donor and a base is a proton acceptor. The acid is said to be dissociated after the proton is donated. An acid and the corresponding base are referred to as conjugate acid-base pairs. Brønsted and Lowry independently formulated this definition, which includes water-insoluble substances not in the Arrhenius definition. Acids according to this definition are variously referred to as Brønsted acids, Brønsted-Lowry acids, proton acids, protic acids, or protonic acids.

(Source: Wikipedia)

Acrylic Resin

Acrylic resin is transparent and colorless with a consistency like molasses. With a base of ethyl acrylate, methyl methacrylate, ethyl methacrylate are use as binders in wall paint and plasters and to make varnishes.

Affresco

The technique used to apply waterborne pigments on fresh, damp plaster.

Aggregate

Granular stone material (sand, gravel, crushed stone) used as the binder in plaster and concrete. It is used to reduce shrinkage in lime and cement mixtures.

Alkaline

 

In chemistry, an alkali (from Arabic: Al-Qaly القلي،‮ ‬القالي is a basic, ionic salt of an alkali metal or alkaline earth metal element. Alkalis are best known for being bases that dissolve in water. Bases are compounds with a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base, especially for soluble bases. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base and are still among the more common bases. Since Brønsted-Lowry acid-base theory, the term alkali in chemistry is normally restricted to those salts containing alkali and alkaline earth metal elements.

The terms "base" and "alkali" are often used interchangeably, particularly outside of a scientific context, but they do not have the same meaning. While all alkaline solutions are basic, not all bases are alkaline.

(Source: Wikipedia)

Base

 

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali (only if OH− ions are involved). This refers to the Brønsted-Lowry theory of acids and bases. Alternate definitions of bases include electron pair donors (Lewis), as sources of hydroxide anions (Arrhenius) and can be (commonly) thought of as any chemical compound that, when dissolved in water, gives a solution with a pH higher than 7.0. Examples of simple bases are sodium hydroxide and ammonia.

Bases can be thought of as the chemical opposite of acids. A reaction between an acid and base is called neutralization. Bases and acids are seen as opposites because the effect of an acid is to increase the hydronium ion (H3O+) concentration in water, whereas bases reduce this concentration. Bases react with acids to produce water and salts (or their solutions).

(Source Wikipedia)

Bees’ Wax

 

The most common wax produced by animals. It’s a tallow-like substance that honeybees secrete when they build their honeycomb. It’s available in a pure white form, or a natural yellow-brown color, and is used as a base for a variety of furniture and floor polishes. In the past, it was used in a variety of ways: as a binder in encaustic paint (heated beeswax to which colored pigments are added), in pastels and in the finishing process; as a component in paint, normally blended with resin; as a way to soften a paint’s translucence; and to increase water repellent properties. In the past, bees’ wax emulsified with lime presumably constituted ‘punic’ wax used in encaustic.

See: WaxCera Punica and Encaustic.

Calce

The Italian word for lime. Ca(OH)2 (Mineral name: Portlandite).

Calcestruzzo

The Italian word for concrete.

Calcium Carbonate

This organic salt, CaCO3 is the main component of the rock used to make lime. It is widely used for the preparation of plasters such as Marmorino.

Carbonatization

This is the physical-chemical process where water is released from plaster during the hardening and drying process. It allows for the reaction between spent lime (Ca(OH)2) and carbon dioxide (CO2) reforming into lime carbonate (CaCO3).

Carboxymethyl-cellulose

In restoration, this is used as a thickener, emulsifier, detergent and stabilizer.

Carnauba

This is very thick wax, coming from the Brazilian palm (Copenicia cerifera). It is added to waxes and polishes to make them more consistent. See: Wax.

Carrara

Carrara is a town in the province of Massa-Carrara (Tuscany, Italy), famous for its valued white marble.

Casein

It is a white, tasteless, odorless protein precipitated from milk by rennin, that is, from milk curds. In alkaline solution, it is used as an adhesive. It is used as a binder in paint or in plaster preparation.

Cement

 

In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term "opus caementicium" to describe masonry which resembled concrete and was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives which were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment and cement. Cements used in construction are characterized as hydraulic or non-hydraulic.

The most important use of cement is the production of mortar and concrete - the bonding of natural or artificial aggregates to form a strong building material which is durable in the face of normal environmental effects.

Cement should not be confused with concrete as the term cement explicitly refers to the dry powder substance. Upon the addition of water and/or additives the cement mixture is referred to as concrete, especially if aggregates have been added.

(Source: Wikipedia)

Cera

The Italian word for wax.

Cera Punica

 

This is virgin bees’ wax boiled repeatedly in seawater. To make the wax soluble, niter and sodium carbonate, in addition to other components including soda and potassium are added. This paste, soluble in water, is used in the encaustic technique.

See Bees’ Wax and Encaustic.

Clay

Produced from the decomposition of rock, and composed primarily of aluminum silicate hydroxide, lime carbonate and silicate. It is porous, very crumbly and malleable. It can be shaped by external pressure and when it dries it, keeps its form. It becomes very hard when baked at high temperatures. There are a variety of types which depends on the percentage of aluminum silicate, iron oxide, carbonate and quartz molecules. Sometimes it is used as an additive to change certain characteristics such as baking time, hardness, refraction and porosity. When clay dries, it shrinks in volume (10%) and it loses hygroscopic water (between the molecules) which is responsible for its plasticity. A similar shrinkage occurs during baking.

Cocciopesto

 

This is an Italian word. Coccio means earthenware and pesto means crushed.

In the past, they used to crush bricks and broken roof tiles to get a sand to mix with lime to make plaster.

In Venice, it was very common to apply a layer of “Cocciopesto Plaster” directly on the bricks before applying normal lime-based plaster. It helped to protect the finish of the wall against the damp of seawater.

The addition of terracotta to slaked lime makes the slaked lime hydraulic, that is, it can harden even in the presence of water. The antique Romans were the first to discover it and used it widely.

Concrete

 

Concrete is a construction material composed of cement (commonly Portland cement) , aggregate (generally a coarse aggregate such as gravel, limestone, or granite, plus a fine aggregate such as sand) and water.

The word concrete comes from the Latin word "concretus", which means "hardened" or "hard".

Cotto

This is the Italian word used for bricks and other materials made of terracotta.

Dry Wall

A board made of several plies of fiberboard, paper, or felt bonded to a hardened gypsum plaster core, is used as a divider and for covering internal walls.

Dye

A water or oil soluble substance which gives color to other materials.

Encaustic

This is an ancient technique which also goes by the term "hot wax painting". The artist heats beeswax to the liquid stage; then mixes in pigmentation. The resulting medium is applied to a surface and reworked once it has dried. The word comes from the Greek meaning ‘engrave with fire’ which describes this painting technique which uses hot wax as a binder for pigments.

Epoxy Resin

This compound came into use in 1949. It is composed of an epoxide resin, therefore its name) and a polyamine hardener which, when mixed together, harden at room temperature releasing heat (for this reason these resins are called thermal hardeners). Yellowing occurs when exposed to sunlight.

Fresco

See “Affresco”.

FRP – Fully Refined Paraffin

Mineral Wax with an oil content of less than 0.5%

Gesso di Bologna (Plaster Gipsum of Bologna)

 

CaSO44 +2 H2O, calcium sulfate hydroxide. It is found in its natural state as a mineral and is used in the preparation of plasters. It is the main component in Spatolato Veneziano.

It is also known as white plaster of Meudon, plaster of Spain and plaster of Vilt. It is a calcium carbonate that comes from sea shell deposits. It is the stable form of chalk. It can be mixed with any binder without changing its characteristics.

Glitter

Small mineral, metallic or plastic particles similar to fish scales that reflect light or sparkle.

Glue - Natural

 

Natural Glue: Glue is a substance used for joining materials.

Before 1930 all the glues were of natural origin: animal glue is obtained by boiling bones and hides (For example, “Lapin” glue comes from rabbit hides).

One of the strongest natural glues is Casein which is obtained from milk.

Another type of glue is derived from fish.

These glues were often used when finishing walls: in the preparation of paints and plasters such as Spatolato Veneziano. Even today, they are used in restorations.

Vegetable glues, which are very weak, were derived by boiling flours and starches in water and adding garlic juice.

Grassello

The Italian word for slaked lime. There is also a modern wall finish called grassello made of a material which is predominantly slaked lime.

Gypsum

 

Gypsum is one of the more common minerals in sedimentary environments. It is a major rock forming mineral that produces massive beds, usually from precipitation out of highly saline waters. Since it forms easily from saline water, gypsum can have many inclusions of other minerals and even trapped bubbles of air and water.

Gypsum has several variety names that are widely used in the mineral trade.

  • "Selenite" is the colorless and transparent variety that shows a pearl like luster and has been described as having a moon like glow. The word selenite comes from the Greek for Moon and means moon rock.
  • Another variety is a compact fibrous aggregate called "satin spar". This variety has a very satin like look that gives a play of light up and down the fibrous crystals.
  • A fine grained massive material is called "alabaster" and is an ornamental stone used in fine carvings for centuries, even eons.

Crystals of gypsum can be extremely colorless and transparent, making a strong contrast to the most common usage in drywall. The crystals can also be quite large. Gypsum is a natural insulator, feeling warm to the touch when compared to a more ordinary rock or quartz crystal. Sheets of clear crystals can be easily peeled from a a larger specimen.

Gypsum crystals can be extremely large - among the largest on the entire planet.

  • Color is usually white, colorless or gray, but can also be shades of red, brown and yellow.
  • Luster is vitreous to pearly especially on cleavage surfaces.
  • Transparency crystals are transparent to translucent.
  • Crystal System is monoclinic; 2/m
  • Crystal Habits include the tabular, bladed or blocky crystals with a slanted parallelogram outline. The pinacoid faces dominate with jutting prism faces on the edges of the tabular crystals. Long thin crystals show bends and some specimens bend into spirals called "Ram's Horn Selenite" Two types of twinning are common and one produces a "spear head twin" or "swallowtail twin" while the other type produces a "fishtail twin". Also massive, crusty, granular, earthy and fibrous.
  • Cleavage is good in one direction and distinct in two others..
  • Fracture is uneven but rarely seen.
  • Hardness is 2 and can be scratched by a fingernail.
  • Specific Gravity is approximately 2.3+ (light)
  • Streak is white.
  • Associated Minerals are halite, calcite, sulfur, pyrite, borax and many others.
  • Other Characteristics: thin crystals are flexible but not elastic, meaning they can be bent but will not bend back on their own. Also some samples are fluorescent. Gypsum has a very low thermal conductivity (hence it's use in drywall as an insulating filler). A crystal of Gypsum will feel noticeably warmer than a like crystal of quartz.
  • Notable occurrences include Naica, Mexico; Sicily; Utah and Colorado, USA; and many other localities throughout the world.
  • Best Field Indicators are crystal habit, flexible crystals, cleavage and hardness.

(Source: Article by Amethyst Galleries, Inc.)

Hydraulic Lime

 

Hydraulic lime is a variety of slaked lime used to make lime mortar. 'Hydraulicity' is the ability of lime to set under water. Hydraulic lime is produced by heating calcining limestone that contains clay and other impurities. Calcium reacts in the kiln with the clay minerals to produce silicates that enable the lime to set without exposure to air. Any unreacted calcium is slaked to calcium hydroxide. Hydraulic lime is used for providing a faster initial set than ordinary lime in more extreme conditions (including under water).

(Source: Wikipedia)

Intonachino

A traditional Italian plaster usually made of lime and marble grains. It is colored by the addition of pigments, but can also be obtained by adding colored marble grains.

Lime

 

Calcium oxide is also known as burnt lime, quicklime or unslaked lime; Calcium hydroxide is also known as slaked lime, slack lime or pickling lime; Hydraulic lime.

Lime, which is a solid white substance, is produced by baking calcareous rock. When treated with water, the lime swells, heats up and becomes calcium hydroxide or spent lime. Wetting it with a quantity of water which is two and a half times its weight, you obtain slaked lime or lime putty, which is the binder for mortar. By mixing the spent lime together with excess water you get a white liquid called lime milk, which is used as a base for various methods of dry painting. Lime can be either rich or poor. Rich or fat lime is derived from pure, or very nearly pure, limestone whereas poor lime comes from magnesium or argyllic (clay) limestone which is less pure. The rich limes are more suitable for painting. They become spent faster, give a high quality shine and set well.

Lime Paint

See Whitewash.

Lime Putty

See Lime.

Lime Water

The common name for saturated calcium hydroxide solution.

Magnesium

Magnesium in its form, MgCO3 is part of the rock from which lime is extracted and can make up 20% of it.

Marble

Marble is a metamorphic rock composed primarily of calcium carbonate (CaCO3). Used since antiquity for sculpting statues, it has always been used in the building trade for the construction of decorative and load bearing elements.

Marmorino

A finishing plaster with a base of spent lime and powdered rock. It is called Marmorino because it is the most natural imitation of marble in terms of both composition and its final appearance.

Marsiglia Soap / (Marseille Soap)

It is unrefined soap and therefore contains more alkaline than regular soap.

Mica

The word mica comes from micare, the Latin word for shine. The term mica stands for a group of phyllosilicates. These minerals tend to form pseudo-hexagonal crystals. The characteristic exfoliating of mica is due to the laminating disposition of these sheets of juxtaposed crystals. The main producers of mica are China, The United States, South Korea and Canada.

Micro-crystalline Wax

This wax, obtained from a mixture of heavy lubricating oil distillates, has an ill-defined crystalline structure and a dark color. It generally has a higher melting point and viscosity than paraffin. Depending on its elemental composition, it can range from soft and sticky to hard and brittle.

Mother of Pearl

This is an organic-inorganic composite material which some mollusks produce as an inner shell layer. It is very strong, resilient, and iridescent.

Nacre

Synonymous with Mother of Pearl.

Paraffin

 

Obtained from petroleum distillates, it is composed of about 90% short chains of hydrocarbons (from 20 to 30 carbon atoms). Some of its properties are:

  • Waterproof
  • Nontoxic
  • Non-reactive to other components
  • Burns with a clean flame
  • Transparent
pH

pH is a measure of the acidity or alkalinity of a solution. It means ‘part or power of Hydrogen”. pH can be measured if an electrode is calibrated with solution of known hydrogen ion concentration. Pure water is said to be neutral. The pH for pure water at 25° C is close to 7.0. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are said to be basic or alkaline.

Pigment

A powdered substance, either natural or artificial, which colors another material. It is notsoluble in water. Substances which are soluble in water are dyes and colorants.

Pittura a Calce

The Italian word for lime wash.

Plaster of Paris

Plaster of Paris is made by heating gypsum to about 300 degrees Fahrenheit, which drives 75% of the water out of the mineral. This reaction absorbs energy, enabling a sheet of drywall containing it to be fire resistant. Heating further to about 350° F drives out the remaining water and results in conversion to the mineral, anhydrite.

Portlandite

The mineral name of Lime.

Pozzolana

This sandy, volcanic ash is a siliceous material which reacts with calcium hydroxide in the presence of water to form hydraulic cement. It was often used in Ancient Rome to produce plasters. In Venice, terracotta was substituted for it.

Primer

This liquid product is applied by brush or roller on surfaces to be painted. This insure good paint or plaster adhesion. Another reason to use primer is to join two substances which are normally difficult to bind together, like plaster and mortar (because of their opposing pHs).

Punica Wax

See: Cera Punica.

Puntinato

The Italian word for some wall finishes which show speckling caused by the presence of black quartz sand.

Quartz

Silicon dioxide, SiO2, from the German, quarz is a mineral which is found mainly in the Earth’s crust (making up about 12% of its volume).

Rasato di Calce

A traditional interior finish used in Venetian construction consisting of liquid lime. It is applied with a brush on lime plaster and sand, and smoothed with a metal trowel. Originally it was applied in up to six or seven layers.

Resina

A class of polymer substances used as a principle component in paints.

Restoration

Conservation of a work of art, returning it nearest to its original condition when there has been deterioration.

Sand

Granular material composed of the detritus which results from the pulverization of rock which is carried to streams, rivers or seas or lies in caves. It is used in mixtures as an aggregate.

Scagliola

A decorative technique used on walls or floors. In Italy it is also called meschia, marble paste or artificial marble. In Germany it is called Stuckmarmor. And in England it is known as Bossi work (from the Italian craftsman who worked in Dublin in the 1700’s). There was a gradual diffusion of this technique throughout Europe between the 17th and 19th centuries. The word Scagliola come from the kind of plaster used which comes from mixing glue made of bones and colored pigments. See: Scagliola Gypsum.

Scagliola Gypsum

A finely powdered plaster which when mixed with water solidifies to a hard porous mass. It solidifies in 15-20 minutes and is useful for making molds or forms, but it is not strong enough to be used as wall plaster. When borax is added to the water during the mixing process, the plaster becomes more resistant.

Semi-refined Paraffin Wax

Wax with an oil content of 1 to 3%

Slack Wax

Mineral wax (it can be paraffin or micro-crystalline) with a high content of oil.

Slaked Lime

A thixotropic material composed of calcium hydroxide Ca(OH)2 and water. This process involves slaking baked calcium hydroxide, with an ample amount of water and aging it in a pit for a minimum of 3–4 months until it becomes fully hydrated.

Spatola

A small trapezoidal-shaped tool with a flat blade, made of wood or metal used by masons, plasterers, and painters for missing or spreading mortar, plaster, or paint.

Spatolato Veneziano

This is a traditional, polished Venetian plaster. It is composed of plaster of Bologna, naturalLapin glue, linseed oil and colored pigments.

Sponge Float

A trowel with a small palette covered with a layer of sponge which is attached to a handle. It is used for smoothing out plasters.

Stucco

The Italian word for finishing plaster made of lime and powdered marbled or a base of plaster. The wore stucco can also mean wall decoration in relief.

Stucco Lustro / Stucco Lucido

Polished Stucco is a plaster made of 1 part plaster, 5 parts grassello, 5 parts of fine marble powder, and glue. It is often confused with Marmorino because they are both shiny.

Stucco Mantovano

A traditional finishing plaster coming from the city of Mantua. It is made of lime putty colored with pigments and applied in several layers with a trowel.

Stucco Romano

The Roman plaster, similar to today’s Marmorino, was composed of up to seven layers of plaster made of lime putty and rock powder with a final smoothing which gave it a slight sheen.

Tadelakt

Tadelakt is a shiny, lime wall coating which is water resistant. It can be used for both interiors and exteriors. It is the traditional coatings of the palaces, hammams and baths of the riads in Morocco. This finish is polished with river stones and treated with a soft, black soap to acquire its water resistance. Tadelakt has soft look with undulations caused by being worked with the river stones. This gives it great decorative capacities.

Terracotta

This is produced by baking clay at temperatures of about 950°C. Its color varies from light yellow to deep red. Dishes, vases, pots, bricks and tiles are made of terracotta.

Thixotropy

The property of a material which is a gel when in repose and which liquefies when it is agitated.

Travertine

This is a calcareous, sedimentary rock which was often used for building, particularly in Rome, until the first millennium BC.

Trowel

A special kind of spatula which has a rectangular shape and a handle. It is used to apply mortars and plasters. It can be made of a variety of materials, but is usually metallic.

Venetian Plaster

Stucco Veneziano.

Wax

 

The term wax indicates an organic substance, natural or synthetic, such as plastic, which is solid at room temperature and becomes liquid when melted. The common characteristics of waxes are:

  • A solid state at 20° C (68° F)
  • A liquid state above 40° C (104° F)
  • A relatively low viscosity, just above the point of fusion
  • A combustion capacity (during which it produces a yellow flame)
  • Impermeable and insoluble in water
  • The capacity to form creamy or gelatinous substances by being dispersed in solvents or waterproofing emulsions.

A catalog of existing waxes:

With the technological evolution, the products on the market termed wax have multiplied, and have a variety of chemical compositions and characteristics.

The cataloging is done in general terms according to their origins:

Natural waxes:

  • Animal (bees’ wax, lanolin, tallow)
  • Vegetable (carnauba, candelilla)
  • Fossil or Mineral (ceresine, montan, ozocherite)
  • Petroleum (paraffin, microcrystalline, petrolatum)*

Synthetic waxes:

  • Ethylene polymers (polyethylene and polyol ethers-esters)
  • Naphthalene chlorates
  • Fischer-Tropsch waxes

*Waxes derived from petroleum:

Unrefined petroleum extracted from underground is a mix of various hydrocarbons and results from the decomposition of small aquatic plants and animals that lived in the oceans millions of years ago.

After the raw material is taken to the refinery, it is undergoes a series of complex processes to obtain a variety of finished products. One of these derivatives is lubricating oil from which we get wax.

Wax Paint

See Encaustic.

White Wash

A type of paint made from slaked lime. Chalk (whiting) can be added along with various other additives.