Glossary

aggregate

The solid part of the plaster that contributes to its durability, aids the carbonation process, and determines the hue of the plaster.

al fresco

The technique of painting on fresh plaster.

al fresco painting

See headword painting on a wet surface.

al secco

The technique of painting on dry plaster.

al secco painting

See headword painting on a dry surface.

animal glue

An organic water-soluble binder obtained from animal skins, parchment, or fish bladders.

animal-based black dyes

Natural organic dyes made from the charcoal of animal matter, mainly bones.

applications

Additions to paintwork, such as relief applications, gilding, semi-precious stones, incisions, and pouncings.

arriccio

A coarse layer of plaster mixed with lime as a binder and coarse sand as aggregate.

artificial colours

Colours resulting from various chemical or physical preparation processes.

azurite

A natural inorganic blue pigment with a slight greenish hue derived from the mineral of the same name.

bazzeo

The medieval term for verdaccio, used in Siena.

bianco sangiovanni

A natural inorganic white-coloured pigment.

binder

An organic or inorganic substance that surrounds and binds together the aggregate or pigment particles, making the mass flexible and thus enabling it to be applied to the support.

caput mortum

a) An inorganic pigment of brownish-red or purple to brownish-purple colour. b) A brownish-red or purple underpainting under the pigments, also called morello.

carbonation

The chemical process of slaked lime reverting to its original state, limestone.

cardboard

A thicker paper on which the preparatory drawing is made in a 1:1 ratio compared to the mural.

casein

An organic binder obtained from skimmed milk using a specific process.

chromatography

An instrumental method for analysing materials.

cinabrese

The Italian term for a natural inorganic pink pigment obtained by mixing two parts of red earth with one part of the bianco sangiovanni pigment.

combined techniques

A combination of several painting techniques on a single mural.

day’s work

A layer of fresh plaster of a size that the painter should be able to paint in one day or while the plaster can still bind with colours.

Destructive analytical methods

Methods that destroy or severely modify the collected sample.

dye

A liquid coloured substance in the form of tinctures, soluble in water or certain liquids, mostly of plant or animal origin.

EDX

See headword scanning electron microscopy with energy dispersive X-ray analysis.

emulsifier

A substance that allows for the temporary mixing of water-insoluble substances with water-soluble ones.

emulsion

The fine distribution of a water-insoluble substance in a water-soluble substance (or vice versa) using a specific emulsifier.

engraving

An incision, one of the final decorations in mural painting.

fresco

The English term for a mural made in the al fresco technique, i.e. by applying pigments to fresh plaster. Not every mural is a fresco!

grasello

The Italian term for rested slaked lime with a creamy texture, which is of extremely high quality and has a strong binding power.

green earth

A natural inorganic green-coloured pigment.

grid

A system of equal squares used to divide a painting composition and transfer it to the wall in an enlarged aspect ratio.

gum arabic

A water-soluble, natural, organic, plant-derived binder and glue extracted from the sap of various species of Indian and African acacia trees.

a) Lines or individual elements such as halos, crowns, draperies, and figures, incised into fresh plaster to aid in the production of a mural; b) A way of transferring a preparatory sketch from cardboard to intonaco; c) Engraving, application decorat

infrared photography

A special photographic method that can record infrared waves, which are otherwise invisible to the eye.

infrared rays

Electromagnetic radiation just below the visible range, invisible to the eye.

infrared reflectography

An instrumental method based on recording waves of infrared rays, which are invisible to the eye.

Infrared spectroscopy

An instrumental method based on the interaction between infrared rays and the analysed material/sample.

inorganic colours

Colours made from natural or synthetic inorganic substances.

instrumental methods

Natural-scientific technological procedures based on evaluating the physical or physical-chemical properties of materials using more or less sophisticated instruments.

intonaco

The top, outermost layer of plaster, which contains the finest sand and the largest amount of lime and is therefore also the smoothest and most suitable for painting.

invasive analytical methods

Methods requiring the collection of samples.

ivory black

A natural organic dye of animal origin made from charred elephant tusks.

lampblack dyes

Natural organic dyes obtained by burning various plant substances or plant oils.

lapis lazuli

A semi-precious stone imported to Europe from Asia. It is used to produce the blue pigment called ultramarine.

lead red

Minium. A synthetic inorganic pigment of a vivid orange-red colour.

lead white

A synthetic inorganic white-coloured pigment.

lead yellow

Massicot. A synthetic inorganic yellow-coloured pigment.

lead-tin yellow

A synthetic inorganic yellow-coloured pigment made from a blend of lead and tin.

lime

A white, creamy, inorganic material composed primarily of calcium oxides and hydroxides, usually calcium oxide and/or calcium hydroxide.

lime milk

An inorganic binder obtained by diluting lime with a lesser or larger quantity of water.

lime painting

Painting on fresh, still damp limewash, applied in one or more layers on dry plaster, either old or new.

lime water

An inorganic binder obtained by diluting slaked lime with a large quantity of water.

limestone

Calcium carbonate, CaCO₃; the basic carbonate rock from which lime is extracted.

limewash

A white coating made from slaked lime.

local tone

A uniform monochrome underpainting limited to a specific part of the entire scene (usually a figure, drapery, or architecture).

malachite

A green-coloured natural inorganic pigment obtained from the mineral with the same name.

marmorino

a) Finely crushed marble or marble flour. b) A painting technique used to imitate marble.

massicot

See headword lead yellow.

microchemical analysis

Procedures for identifying pigments, plasters, and binders based on chemical reactions.

mineral black pigments

Natural inorganic black-coloured pigments obtained from various mineral substances such as black chalk, black earth, and black shale.

minium

See headword lead red.

mixed colours

Colours made as a mixture of mineral and organic pigments.

mixed techniques

The use of multiple painting techniques on a single mural.

morello

A reddish-brown or purple underpainting under some pigments that require a base due to chemical reactions with alkaline lime, poor opacity, or high price.

morphological analyses

Procedures applied to understand the structure of the material/sample, plaster layers, and colour layers.

mural painting

A painting made on a wall as the support for the colour layers.

natural colours

Colours derived from substances found in nature, such as earths, minerals, and plant or animal matter.

natural-scientific technological analyses

Various methods of laboratory research, allowing for more accurate characterisation and identification of both inorganic and organic substances.

non-destructive analytical methods

Methods that do not destroy or modify the collected sample.

non-invasive analytical methods

Methods that do not require a sample to be taken; they are usually used in situ.

oil

An organic binder of plant origin, insoluble in water.

OM

See headword optical microscopy.

optical microscopy (OM)

llows for the optical analysis of a sample using transmitted or reflected light under various magnifications.

organic colours

Colours obtained from plant and animal-based substances or synthetically produced organic compounds.

painting base

priming. The preparation of the painting base for the al secco technique.

painting on a dry surface

Painting on dry plaster.

painting on a wet surface

Painting on fresh, still-damp plaster, i.e. al fresco.

paratacamite

A green or greenish-black mineral with a chemical composition similar to azurite and malachite, except that it also contains chlorine.

pastiglia

An addition of a relief decoration in mural painting.

pigment

Coloured solid particles or coloured powder applied to a painting base using a binder.

pit black

A natural organic dye of plant origin.

plant-based black dyes

Natural organic dyes extracted from charred wood or other plant matter, which must be ground and washed well to remove any impurities.

plaster

A mixture of lime as the binder and sand or crushed marble (marmorino) as the aggregate.

polishing

The final process in painting on fresh plaster, when a hard, flat object is used to smooth the painted surface.

pontata

A sizeable horizontal band of fresh painting plaster applied along the entire surface to be painted.

pounce

See headword pouncings.

pouncing

See headword pouncings.

pouncings

Decorations of certain elements of the mural, such as crowns, boxes, bands, or architectural elements.

preparatory drawing

a) All preparatory sketches drawn before the actual painting work on the support; b) an underdrawing made on intonaco.

priming

See headword painting base.

quicklime

Calcium oxide (CaO), a solid porous substance produced by burning carbonate rocks, especially limestone, at temperatures above 800 °C.

radiography

A natural-scientific technological method used to record X-rays, which appear as a collection of light and dark spots on the radiographic plate.

Raman spectroscopy

A spectroscopic method where a sample is irradiated with a laser (of various wavelengths) while observing the inelastic scattering of light, which is converted into a spectrum.

red ochre

A natural inorganic pigment of earth origin.

resin

An organic binder of plant origin, insoluble in water. It is thicker than oil and rarely used in mural painting.

sample

A representative part of the plasters and colour layers of a specific mural.

sand

Sand serves as the aggregate for the plaster and is crucial for its durability.

Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (SEM–EDX)

A combined instrumental method of material analysis, where a beam of electrons is used to observe the surface of a sample and identify its elemental composition.

SEM–EDX

See headword scanning electron microscopy with energy dispersive X-ray analysis.

Sienese earth

A natural inorganic pigment, a special type of yellow ochre.

sinopia

a) A natural brick-red-coloured inorganic pigment named after Sinop, a city by the Black Sea; b) A preparatory sketch drawn on arriccio (the lower layer of plaster).

slaked lime

Thick white paste, calcium hydroxide, Ca(OH)₂.

smalt

Blue-coloured synthetic inorganic pigment.

spolvero

A manner of transferring a preparatory drawing to the painting base.

stencil

An element cut in positive or negative from cardboard, tougher paper, parchment, leather, or metal, used to apply the same design to a wall multiple times in succession, thus producing a uniform and repeating pattern.

stratigraphy

A cross-section of a sample.

sulphatisation

The chemical transformation of limestone to gypsum, usually caused by the harmful effects of air polluted with sulphur dioxide (SO₂).

support

The foundation on which the mural is painted. In mural painting, the support is a wall made of stone, brick, or a combination of stone and brick bound together with mortar.

synthetic colours

See headword artificial colours.

TEM

See headword transmission electron microscopy.

tempera

Types of painting techniques where pigments are mixed with an organic binder.

thin foil

An extremely thin cross-section, usually less than a millimetre thick.

transmission electron microscopy (TEM)

An instrumental method allowing for even greater magnifications than scanning electron microscopy (SEM).

transparent paper

Thin translucent paper enabling the composition or the individual parts of the mural to be transferred onto the wall in the same proportions as they appear on the preparatory drawing.

tratteggio

The Italian term for painting using thin parallel lines, allowing for fine colour transitions.

ultramarine

A natural inorganic pigment of a warm blue colour with a violet hue, produced by grinding a semi-precious stone called lapis lazuli.

ultraviolet fluorescence

A non-invasive instrumental method of mural analysis based on fluorescence, one of the reactions caused by UV rays when they collide with matter.

ultraviolet photography

A special photographic method capable of recording ultraviolet waves, which are invisible to the eye.

ultraviolet rays

Electromagnetic radiation just above the visual field that is invisible to the eye.

umber

A natural inorganic brown-coloured pigment. Its chemical composition is iron oxide with traces of manganese, Fe₂O₃.

underdrawing

A preparatory drawing under the colour layer. See also headwords sinopia and preparatory drawing.

underpainting

A monochrome colour application serving as a base for colour modelling.

veneda

A grey underpainting under some pigments that require a base due to chemical reactions with alkaline lime, poor opacity, or considerable price.

verdaccio

A green underpainting used as a base for figures and carnations and as the first modelling layer.

vine black

A natural organic dye of plant origin (charcoal made of vine wood, which gives the colour a bluish-black hue).

water-soluble binders

Binders soluble in water, such as eggs, milk, starch, and animal glue.

wax

An organic binder, insoluble in water and used mainly for the encaustic painting technique in the Antiquity.

X-ray diffraction (XRD)

See headword X-ray diffraction analysis.

X-ray diffraction analysis (XRD)

An instrumental method of material analysis based on the interaction of X-rays with the matter they strike.

X-ray fluorescence (XRF)

An instrumental method used to determine the elemental composition of various materials, mainly inorganic ones.

X-rays

Electromagnetic radiation, invisible to the eye.

XRD