Any organic or inorganic substance (or material) used in a very small quantity and mixed with paint, plaster, mortar or cement as an accelerator, plasticiser, stabiliser, fluidiser or retarder (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Granular material (sand, pozzolan, brick powder, marble dust, calcite), inert or reactive, used in combination with a binder (e.g. lime) to prepare mortars. The addition of aggregates helps to give volume to the mix so that it can be used also in thick layers, to increase setting, and to balance the shrinkage related to the setting of lime (Resta di Stucco Project).

Expression used to indicate a sculpture that can be seen from all sides or that emerges from the background with the fullness of its volume (Treccani.it vocabulary, translated, ad vocem).

Animal glue is a protein substance, extracted from animal tissues, which has an adhesive function. There are different types of animal glues depending on the raw material and the animal from which it is extracted: tendons or skin (skin glue), bones (bone glue), various parts of fish (fish glue), etc. (Resta di Stucco Project).

Armatures (usually iron bars or nails, sometimes wooden sticks) are used in the support structure of a stucco to build the skeleton of a figure or as an anchor to attach highly projecting three-dimensional figures to the wall structure behind (Resta di Stucco Project).

Mortar with a special mix and working process that simulates the appearance of a natural stone. From the second half of the 19th century it was extensively used for decorative elements for façades and architectural surfaces (Resta di Stucco Project).

Type of sculpture in which the figures are represented on a background, from which they protrude in reduced relief (Treccani.it vocabulary, translated, ad vocem).

Material that provides stable bonds between several loose components (i.e. aggregates). The most commonly used binders for stuccoes are lime and gypsum (Resta di Stucco Project).

See “Quadrello”.

Powder obtained from the crushing of bricks (roof tiles, bricks, etc.). It is part of a mortar mix as a reactive aggregate (Resta di Stucco Project).

A widespread mineral, chemically composed of calcium carbonate (CaCO₃), the main constituent of limestones (Resta di Stucco Project).

Lime obtained by firing limestone (Resta di Stucco Project).

Chemical reaction in which calcium hydroxide (Ca(OH)₂, slaked lime) reacts with carbon dioxide (CO₂) to form insoluble calcium carbonate (CaCO₃). This reaction, with the loss of water, allows a lime-based mortar to set (Resta di Stucco Project).

Organic binder obtained from milk (e.g. curd or cheese) (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Imprint of a sculpture or inscription or coin, made in wax, clay, plaster to draw copies of the original object from the shape thus obtained (Treccani.it vocabulary, translated, ad vocem).

Elemental concave molding with a profile approximately a quarter-circle (Treccani.it vocabulary, translated, ad vocem).

Layer of coarse-grained plaster that defines the volumes of a stucco. The mixture is usually composed of lime, aggregates and sometimes gypsum. Sometimes this layer consists of several layers with different composition and can reach substantial thicknesses, up to several centimeters (Resta di Stucco Project).

See “Coarse layer”.

Architectural part that is located at the end of a wall in connection with the elements of the ceiling (Treccani.it vocabulary, translated, ad vocem).

A discontinuity in an architectural surface or wall painting, resulting in a visible separation of one part from another, that extends through one or more layers (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Network of thin minor cracks usually affecting the final layer of a surface (Resta di Stucco Project).

Preparatory drawing technique using a pointed tool or other sharp instrument to scratch a plaster surface (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Lime obtained by burning dolomitic limestones containing varying amounts of magnesium (Resta di Stucco Project).

A substance of crystalline, filamentous, or powdery appearance that forms on the top of a surface, caused by the migration of soluble salts and evaporation of water (Resta di Stucco Project).

Section of wall or ceiling corresponding to a flat area in the decorative design, having the shape of a strip (Treccani.it vocabulary, translated, ad vocem).

Mortar mix with a high percentage of binder (Resta di Stucco Project).

Painting technique used to imitate different types of marble (Resta di Stucco Project).

The last, fine-grained, thin and well-evened layer of plaster (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Last finishing of a stucco decoration with an application of lime milk, to give the surface a uniform appereance. Finishes can also be polychrome or made with metal leafs (Resta di Stucco Project).

Polished plank of hardwood, or rectangular steel blade, fitted with a handle on one of the faces, used to level and smooth mortars and other mixes on flat surfaces (plaster, floors) (Treccani.it vocabulary, translated, ad vocem).

Application of a coat of metal or powders to a surface. The very thin gold leaves were laid on the completely dry stuccoes. Silver leaves were rarely used because of their tendency to oxidize. Sometimes the effect of gold was obtained with less valuable metals (bronzine or porporin) or imitated with yellow pictorial layers (Resta di Stucco Project).

An area of fresh plaster (intonaco) applied as one part of a fresco (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Gouache gilding consists of applying a gold leaf on a clay layer of bolus. The bolus provides a flexible surface that allows the gold to be polished with an agate burnisher, resulting in a shiny, very smooth effect (ARTEnet.it glossary, ad vocem).

Grain size of an aggregate, often selected with a sieve according to the function of mortar to be produced or the surface effect sought by the plasterer (Resta di Stucco Project).

Soft mineral composed of calcium sulfate dihydrate (CaSO₄·2H₂O). Finely ground it is used as an aggregate, while heated (calcinated) it becomes a binder. Depending on the temperature to which it is exposed, a material with different characteristics is obtained: fired at 120-180 °C --> calcium sulfate hemhydrate (CaSO₄•1/2 H₂O, plaster of Paris), fired at 180-250 °C --> soluble anhydrite (CaSO₄(α)), fired above 250 °C --> insoluble anhydrite (CaSO₄(β)). Gypsum can be used as a binder also without aggregates because during setting, unlike lime that shrinks, it expands in volume (Resta di Stucco Project).

Sculpture form subordinate, like bas-relief, to a background, but with stronger relief, i.e. tending toward the all round in the modeling of figures, with plastic rather than pictorial effect (Treccani.it vocabulary, translated, ad vocem).

Design transfer from a cartoon onto a plaster employing a point or stylus (also called the stylus method) (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Gathering information using analytical techniques that require the taking of samples from the artwork (Resta di Stucco Project).

Mechanical roughening (e.g. hammering, scoring, scraping) of a surface in order to prepare for an additional layer of plaster (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Mix with a high percentage of aggregate (Resta di Stucco Project).

A binding material resulting from the calcination (burning) of limestone. In Italian Switzerland the term “calcina” is used for limestone, lime, lime putty (Vocabolario dei dialetti della Svizzera italiana, ad vocem, 1952). See also “Lime cycle”.

Limestones (CaCO₃, calcium carbonate) are fired at a temperature of about 800-1000 °C to obtain “quicklime” (CaO calcium oxide, CaCO₃→CaO+CO₂); by adding water, through the process of hydration, the quicklime is converted to slaked lime (calcium hydroxide CaO+H₂O→Ca(OH)₂); once in place, through reaction with carbon dioxide (CO₂) in the air, the process of “carbonation” takes place whereby calcium carbonate (CaCO₃) is formed again (Ca(OH)₂+CO₂→CaCO3+H₂O) (Resta di Stucco Project).

Dispersion of calcium hydroxide (Ca(OH)₂) in water. It can be used as a binder in lime paint (Resta di Stucco Project).

Quicklime slaked with a slight excess of water, material with the consistency of a cream (Resta di Stucco Project).

Paint composed of lime and water (Resta di Stucco Project).

Saturated aqueous solution of calcium hydroxide (Ca(OH)₂) (Resta di Stucco Project).

Quicklime particles that have not been completely slaked during the mortar manufacturing process. They hydrate on contact with water or moisture in the air, expanding their volume (Resta di Stucco Project).

Fine powder made from crushed and ground marble chips, of calcitic or dolomitic origin (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

A lime and marble dust-based finish used for cladding (also called stucco lustro). The glossy surface effect is given by soap added directly unto the mixture or as a final coat, heated with a hot iron. Sometimes a final layer of wax or oil is added (Resta di Stucco Project).

Visual observations and scientific characterization of the materials that constitute an artwork to obtain information about their composition and condition. These informations may be useful in dating, in understanding the techniques by which they are made, or in defining a conservation intervention (Resta di Stucco Project).

Laying of a gold leaf over an adhesive (the mission, usually oil-resin based) that can be applied with a brush (Resta di Stucco Project).

A mixture of binders, water, aggregates and maybe additives/admixtures (organic and/or inorganic) in different ratio to obtain suitable working and physical-mechanical properties. A mortar is defined as 'non-hydraulic' or 'hydraulic' in relation to its ability to setting by carbonatation (exposure to carbon dioxide in the air) or in the presence of water (hydraulic mortar). Mortar is used to bind elements of a masonry (bedding mortar), to protect masonry (plaster) or to shape decorative elements (stucco) (Resta di Stucco Project).

A cavity or matrix in which a fluid or plastic substance is poured (casted) into a desired finished product or a reverse moluld that is beaten in the lime plaster to give the decorative shape (Resta di Stucco Project).

Decorative architectural element modeled with recesses and reliefs (Resta di Stucco Project).

Natural hydraulic lime (NHL) is produced by heating (calcining) limestone that naturally contains clay and other impurities i.e. containing silica and alumina: it can set both in air or water. The raw materials are fired at 1100-1200 °C. During firing, part of the calcium oxide (CaO) combines with silica and alumina to form calcium silicates and aluminates (Ca₂SiO₄ e Ca₃Al₂O₆), components with hydraulic properties (Treccani.it vocabulary, translated, ad vocem).

Gathering information directly on the artwork, using techniques that do not require sampling and do not modify or damage the material (Resta di Stucco Project).

The decorations are not made directly on site but in the workshop or in the building site and then mounted on site and joined together to compose the desired decorative pattern. This technique is used to overcome the difficulties of some working processes or to meet the need for serial production (Resta di Stucco Project).

Tool used to detect the presence, direction and diameter of reinforcing bars present inside concrete or mortar elements (Resta di Stucco Project).

Protective and/or decorative coat which is applied to architectural surfaces (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Siliceous or silica-aluminous (Ca₂SiO₄ e Ca₃Al₂O₆) material used as a reactive aggregate. When finely ground and in the presence of water, it reacts by hydraulic setting with aerial lime (Resta di Stucco Project).

The first definition of a work on the wall made with brush or charcoal (Resta di Stucco Project).

Holes purposely made in a wall to support a suspended scaffolding platform (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Sacred vessel in the form of a cup with a lid, intended to hold consecrated hosts (Treccani.it vocabulary, translated, ad vocem).

The bricks, called in Lombardy “quadrelli” or “pianelle” depending on their size, were used to build the supporting structure of altars, pilasters, entablatures, and of all the projecting architectural or decorative elements. The "flat tiles," in particular, small and thin paving slabs, were well suited for composing different profiles (Resta di Stucco Project).

Calcium oxide (CaO) obtained by calcination at 800-1000 °C of limestone, a reactive material that easily reacts with water (Resta di Stucco Project).

A relatively coarse plaster coat applied before the plaster layer for levelling the unevenness of the support (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

Running mould are metal templates made by sheet zinc mould, fixed to a timber framework, known as a horse, which is able to “run” or glide along the wall, via horizontal or vertical timber battens temporarily fixed to the wall (Resta di Stucco Project).

One of the most common aggregates in the composition of a mortar. In the archival documents consulted during the research, sand is usually referred to by the generic term “sabbione”, a coarse-grained sand. In several works examined, the grain size of the sand used for the floating layers is actually coarse, mixed and unselected (Resta di Stucco Project).

Technique used to imitate decorative stones (e.g., marble, breccia, porphyry) with a mixture of plaster, animal glue and pigments (Resta di Stucco Project).

The process during which the mixture of a binder (lime, cement) with water, and possibly other materials (sand, crushed stone, gravel), gets harder through a carbonation or hydration reaction (Resta di Stucco Project).

Last layer of mortar that is used to finish the surface of a stucco decoration, making it smooth and homogeneous. The mixture is usually composed of lime and fine aggregates (marble dust or other whitish stones); the thickness is usually a few millimeters (Resta di Stucco Project).

See “Setting coat”.

Calcium hydroxide (Ca(OH)₂ obtained by mixing quicklime and water (Resta di Stucco Project).

Method of applying a straight lines of a drawing onto plaster, by stretching a piece of string soaked in pigment (or without, when the line is impressed into fresh plaster), pulling back and releasing it so that it snaps against the painting, leaving a mark (Resta di Stucco Project).

Metal or wooden stick, with flat ends generally used for modeling soft materials (Resta di Stucco Project).

Very shallow relief sculpture with carving only millimetres deep. To give the illusion of greater depth, the thickness of the carving gradually decreases from the foreground to the background. In some ways it is more similar to a two-dimensional image than a three-dimensional sculpture (Wikipedia.org, ad vocem).

Wooden or flexible steel spatula used for painting, plastering, modelling (Treccani.it vocabulary, translated, ad vocem).

Moldable material in its fresh state, used to coat architectural elements (such as masonry, columns, capitals, cornices, etc.) and/or to model bas-relief, high-relief or full-round sculptures, cornices and moldings. The mortar is composed of binders (lime and/or gypsum), aggregates (sand, spatic calcite, pozzolan or cocciopesto) and any additives used to modify its properties (e.g., plasticity or setting time) (Resta di Stucco Project).

Usually a stucco decoration is formed by a supporting structure, iron or wooden armatures, and plaster applied in several coats (a first coarse, a setting and a finishing layer) (Resta di Stucco Project).

A “stucco forte” is defined as a mixture composed mainly of lime as a binder (Resta di Stucco Project).

Structure supporting the stucco decoration projecting from the wall, made of stone or bricks of different sizes (Resta di Stucco Project).

In architecture, carved male figure used in place of column or pillar to support overlying architectural members (Treccani.it vocabulary, translated, ad vocem).

Spatula characterized by the presence of teeth on the blade (Resta di Stucco Project).

Tool used by masons to take and distribute mortars during masonry construction or plaster laying (Resta di Stucco Project).

The process of removal of various overlying paint layers from a surface (Resta di Stucco Project).

In the technique of carving and sculpture, especially in bas-relief, denomination of the deepest grooves which form an acute angle with the plane formed by the bottom of the work (Treccani.it vocabulary, translated, ad vocem).

Described by Cherubini (Milanese-Italian vocabulary) as a “kind of iron bar or strapping struck in the plane in imitation of a wavy ribbon”. It is a bar of iron forged and riveted in an alternating direction, with a square section of different sizes. This particular metalwork ensured better adhesion of the mortar and allowed the plasterers to bend the bars as they worked, obtaining the desired shapes (Resta di Stucco Project).

Painting done directly on the architectural surface, either “a fresco” (on wet plaster) or “a secco” (on dry plaster) (Resta di Stucco Project).

A solid or semi-solid, slightly greasy, water-insoluble, organic substance, principally containing compounds of high molecular weight. They are derived from animals, plants, petroleum or are synthetic in origin (EwaGlos - European Illustrated Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces, ad vocem, 2016).

A white surface coating (usually a mixture of slaked lime and water) applied to the stucco decorations to return them to a white colour (Resta di Stucco Project).

In payments associated with a construction site, wine was always purchased in large quantities because it was part of the wages paid to workers of all grades: from the simple apprentice to the painter (Resta di Stucco Project).