Gesso (; "

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. C ...

", from the la,

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywa ...

, from el, γύψος) is a white

paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...

mixture consisting of a binder mixed with

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

, or any combination of these. It is used in painting as a preparation for any number of substrates such as wood panels,

canvas Canvas is an extremely durable plain-woven fabric used for making sails, tents, marquees, backpacks, shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handbag ...

and sculpture as a base for paint and other materials that are applied over it. Gesso acrylic brush

Description

"''Gesso''", also known "glue gesso" or "Italian gesso", is a traditional mix of an animal glue binder (usually rabbit-skin glue), chalk, and white pigment, used to coat rigid surfaces such as wooden painting panels or masonite as a permanent absorbent

primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...

substrate for

painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and a ...

. The colour of gesso is usually white or off-white. Its absorbency makes it work with all painting media, including water-based media, different types of

tempera Tempera (), also known as egg tempera, is a permanent, fast-drying painting medium consisting of colored pigments mixed with a water-soluble binder medium, usually glutinous material such as egg yolk. Tempera also refers to the paintings done ...

and

oil paint Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and ...

. It is also used as a base on three-dimensional surfaces for the application of paint or

gold leaf Gold leaf is gold that has been hammered into thin sheets (usually around 0.1 µm thick) by goldbeating and is often used for gilding. Gold leaf is available in a wide variety of karats and shades. The most commonly used gold is 22-kara ...

. Mixing and applying it is a craft in itself, as it is usually applied in ten or more extremely thin layers. The hide glue mixture used to make the traditional gesso is rather brittle and susceptible to cracking, thus making it suitable for rigid surfaces only.

Variations

Half-chalk ground

For priming flexible

, an

emulsion An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Alth ...

of gesso and

linseed oil Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, also called "half-chalk ground", is used.

Acrylic gesso

Acrylic gesso is a mixture of white pigment and some kind of filler (chalk, silica, etc.) and

acrylic resin 186 px, Polyhydroxyethylmethacrylate is a typical acrylate resin. An acrylic resin is a thermoplastic or thermosetting plastic substance typically derived from acrylic acid, methacrylic acid and acrylate monomers such as butyl acrylate and or ...

dispersed in water. It produces a soft, flexible non-absorbent surface that is technically not ''gesso'' (although it is commonly called that by its manufacturers). It can contain calcium carbonate (CaCO₃) to increase the absorbency of the primer coat as well as

titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insolu ...

or "titanium white" as a whitening agent. It is sold premixed for both

sizing Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorptio ...

and priming panels and flexible

for

. Art supply manufacturers market canvases pre-primed with acrylic gesso. Acrylic gesso can be colored, either commercially by replacing the titanium white with another pigment, such as

carbon black Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid ...

, or by the artist directly, with the addition of an

acrylic paint Acrylic paint is a fast-drying paint made of pigment suspended in acrylic polymer emulsion and plasticizers, silicone oils, defoamers, stabilizers, or metal soaps. Most acrylic paints are water-based, but become water-resistant when dry. ...

. Acrylic gesso can be odorous, due to the presence of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous ...

and/or

formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...

, which are added in small amounts as preservatives. Acrylic gesso's non-absorbent acrylic polymer base makes it incompatible with media that require an absorbent substrate, such as egg tempera. ''The Painter's Handbook'' notes a problem with using oil paints over an acrylic gesso ground instead of a traditional oil ground, citing a mismatch in flexibility that over time could cause the oil paint to delaminate.

Use in sculpture

Gesso is used by

sculptors Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

to prepare the shape of a final sculpture (fused bronze) or directly as a material for sculpting. Gesso can also be used as a layer between sculpted wood and gold leaf. In this case, a layer of refined and coloured clay called 'bole' is used to cover the gesso before applying the gold. Bole is usually red in colour.

References and sources

; References ; Sources
"The Technique of Raised Gilding"
by Jerry Tresser, 1992.

External links

* {{Commons category-inline, Gesso Gilding Painting materials Italian words and phrases