Gesso is the white primer applied before painting to seal and prepare the surface. Learn its history from medieval gypsum grounds to modern acrylic gesso and how to use it.
Before a painter puts color to canvas, someone has to put gesso to canvas. That white coating is the layer that makes painting possible. It seals the surface, creates a paint-ready ground, and provides the right amount of absorbency and texture for the paint to adhere to. Without it, oil paint would rot the canvas fibers, acrylic paint would soak in and lose its vibrancy, and tempera would have no ground to bond with. Gesso is the invisible foundation of every painting, and most viewers never think about it.
Gesso is a white coating applied to a painting surface to create a ground for paint. The word comes from the Italian "gesso," meaning chalk or plaster, derived from the Latin "gypsum." Traditional gesso is a mixture of animal glue binder (usually rabbit skin glue), chalk or gypsum, and white pigment, applied in multiple layers to rigid surfaces like wood panels. Since the mid-20th century, the term has also been used for acrylic gesso, a commercial primer made from acrylic polymer, calcium carbonate, and titanium white pigment, which can be applied to both rigid and flexible surfaces. Despite sharing a name, traditional gesso and acrylic gesso are chemically different materials.
This entry covers the history of gesso from medieval panel painting to modern acrylic formulations, the difference between traditional and acrylic gesso, how gesso works, and how to use it.
Gesso does three things. It seals the surface, preventing paint from soaking into the raw material beneath. It creates a ground with the right level of absorbency, giving the paint something to bond to. And it provides a consistent white or off-white surface that affects how colors appear when applied over it. A white gesso ground makes oil and acrylic colors appear brighter and more luminous because the white reflects light through the paint layers.
The preparation of a painting surface follows a specific sequence. First, the surface is sized, which means sealing it with a glue or polymer to prevent the gesso or paint from penetrating the fibers. Then gesso is applied in one or more layers. For oil painting, the gesso ground must be slightly absorbent so the oil binder can grip the surface, but not so absorbent that it sucks the oil out of the paint. For acrylic painting, the ground can be more absorbent because acrylic binder adheres well to porous surfaces. For egg tempera, the ground must be highly absorbent, because tempera bonds by sinking into the surface rather than forming a film on top of it.
Traditional gesso predates stretched canvas as a painting support. It was developed for panel painting, where a hard, smooth ground was needed to prepare wood for tempera and gilding. Use of gesso grounds is documented since medieval times. Italian painters used a gesso made from gypsum (calcium sulfate) and animal glue, applied in multiple layers. The initial layer, called gesso grosso, contained coarse gypsum particles and provided bulk. The final layers, called gesso sottile, contained fine gypsum particles slaked in water, which produced a smooth, opaque, reflective surface that could be sanded and polished to an ivory-like finish.
In the 14th century, Giotto used a finishing gesso of parchment glue and slaked plaster of Paris. Medieval tempera painters also used gesso duro (hard gesso), a less absorbent composition used for building up low-relief decoration in areas intended for gilding. Patterns were pressed into the gesso with small carved woodblocks before the gilding was applied. The Britannica entry on gesso documents these historical formulations in detail.
In northern Europe, a different gesso tradition developed. Rather than gypsum, northern painters used chalk (calcium carbonate) mixed with animal glue. This produced a slightly different surface quality, and the distinction between southern (gypsum) and northern (chalk) gesso grounds is one of the technical differences that art conservators use to distinguish paintings from different regions.
Traditional gesso is hard and brittle. This is fine for rigid supports like wood panels, but it cracks and flakes on flexible surfaces like canvas. When canvas replaced panel as the dominant painting support in the 16th century, painters adapted by using thinner gesso layers or switching to oil-based primers that remained flexible. The traditional glue gesso continued to be used for icon painting and on panels, but most easel painters on canvas used a combination of animal glue size and oil-based primer.
The major 20th-century development was the invention of acrylic gesso. In 1957, the art supply company Utrecht created one of the first acrylic dispersion painting grounds, called New-Temp Acrylic Gesso. This was a revolutionary product. Before acrylic gesso, preparing a canvas for oil painting was a two-week process: apply glue sizing one day, wait, apply slow-drying lead-based oil primer the next, wait two weeks for it to cure. Acrylic gesso served as both sizing and primer in one step, dried in hours rather than weeks, and contained no toxic lead. The Blick Art Materials guide to the evolution of gesso documents this history.
By the 1950s, titanium white and zinc white had mostly replaced lead white in commercially prepared primers. Today, acrylic dispersion gesso is the most common ground used by contemporary painters. Even in Italy, the modern product is known as "gesso acrilico." The word "gesso" is now widely accepted as a generic term for water-based acrylic primer, though traditionalists note that acrylic gesso is chemically different from traditional glue gesso and cannot serve as a substitute for tempera painting.
Traditional gesso is made from animal glue (usually rabbit skin glue), chalk or gypsum, and white pigment. It is mixed hot, applied in multiple layers (sometimes as many as 12 to 20 for icon painting), and sanded between layers to create a smooth, hard surface. Traditional gesso is very absorbent, which makes it the correct ground for egg tempera and water gilding. It is also used for oil painting on panel, where its absorbency helps the oil paint bond to the surface. Traditional gesso should only be applied to rigid supports. On canvas, it will crack and flake as the fabric flexes. The Museum of Fine Arts Boston CAMEO database provides technical specifications for traditional gesso formulations.
Acrylic gesso is a mixture of acrylic polymer emulsion, calcium carbonate (for texture and absorbency), and titanium dioxide (for whiteness and opacity). It is flexible, dries quickly, and adheres to almost any surface: canvas, wood, hardboard, paper, and even some metals. It serves as both sizing and primer, eliminating the need for a separate glue size layer. Acrylic gesso can be applied to canvas without cracking, which is its main advantage over traditional gesso. It can be thinned with water, cleaned up with water, and tinted with acrylic paint to create a colored ground. The main drawback is that acrylic gesso is less absorbent than traditional gesso, which makes it unsuitable for egg tempera. There is also a theoretical concern about long-term adhesion of oil paint over acrylic gesso, because the flexibility of the acrylic layer differs from the rigidity of dried oil paint. The Painter's Handbook notes that this mismatch could cause oil paint to delaminate over time, though in practice this has not been a widespread problem for paintings made since the 1960s.
Oil primer, sometimes called oil ground, is a traditional alternative to gesso for canvas preparation. It consists of lead white or titanium white pigment bound in linseed oil, applied over a glue size. Oil primer creates a smooth, non-absorbent surface that is the traditional ground for oil painting. It is more flexible than traditional gesso and more compatible with oil paint than acrylic gesso. However, it is slow-drying (two weeks or more) and, in the case of lead white formulations, toxic. Modern oil primers using titanium white are safer but still require long drying times.
For acrylic gesso on canvas, start with a clean, stretched canvas. Apply the gesso with a wide brush or a painting knife in thin, even layers. Two to three coats are standard, with sanding between coats if you want a smoother surface. The first coat should be thinned slightly with water to help it penetrate the canvas weave. Subsequent coats can be applied full strength. Allow each coat to dry completely before applying the next, which takes about 1 to 2 hours depending on humidity. For a very smooth surface, sand the final coat with fine-grit sandpaper.
For traditional gesso on panel, the process is more involved. Rabbit skin glue is soaked in water, then heated (not boiled) until liquid. Chalk or gypsum is added to create a paste, which is applied warm in multiple layers. The first layers (gesso grosso) use coarser particles. The final layers (gesso sottile) use finer particles. Each layer is sanded smooth before the next is applied. The result is a hard, white, polished surface ideal for tempera or gilding.
For oil primer on canvas, first apply a glue size (rabbit skin glue or PVA size) to seal the canvas fibers. Then apply one or two coats of oil primer with a brush or knife, allowing each coat to dry for at least a week. The surface can be lightly sanded between coats. Oil-primed canvas is the traditional choice for professional oil painters who want the smooth, non-absorbent ground that old master paintings were made on.
Gesso is rarely visible in finished paintings, but you can see its effects. The smooth, luminous surfaces of Renaissance panel paintings at the National Gallery in London or the Uffizi in Florence are the result of carefully prepared gesso grounds beneath tempera and oil. The MITRA (Materials Information and Technical Resource for Artists) guide to grounds and primers provides detailed technical information about historical and contemporary ground layers, including analysis of how different grounds affect paint aging and conservation.
For more on the surfaces that gesso prepares, read our entries on canvas and canvas panels. For the tools used to apply paint over gesso, see our entries on the brush and palette knife. And for a deeper understanding of how surface preparation affects painting, read our post on oil painting techniques.
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