Many of the best supports don’t provide a surface which is suitable for the direct application of paint. This is particularly true of egg tempera and oil paints on wood panels or stretched fabrics, some of the most important combinations for professional artists over the centuries. So, from ancient times on, it has been common to apply a ground to the support, which will ensure good adherence of the paint.
The traditional ground for both egg tempera and oils consists of an initial sealing layer of size, such as ‘rabbit skin’ glue, then a series of layers of semi-absorbent chalk or gypsum known as gesso. Formulae for the gesso mixture vary, but usually include more glue and may include pigment, which can be coloured rather than white. For use on stretched canvas, some drying oil such as linseed is often added as it is thought to increase mechanical flexibility.
This paint section cut by Elizabeth Steele from a painting by Honoré Daumier made on wood panel shows the relatively thick white layer of ground underneath layers of pigment-rich oil paint.
In traditional painting practice, the ground is never seen, and is always covered by paint: leaving ground exposed in a finished painting would have been as shocking as exposing your underwear in public. Other than during conservation work, the only time that you should see the ground in such a painting is during its early stages. We are fortunate enough to have a few works by old masters which have been abandoned while their ground was still visible.
Michelangelo’s abandoned ‘Manchester Madonna’ was being painted in egg tempera on wood on which a traditional gesso had been laid as the ground. Those are the off-white areas at the left, over which he had painted a characteristic green earth underpaint where there was to be flesh. Applied with care and in many thin layers, the gesso provided a perfect semi-absorbent smooth surface on which egg tempera or oils adhered well and could take fine detail.
A few years earlier, Leonardo da Vinci had abandoned his Adoration of the Magi at a slightly earlier stage, when he left Florence. Although he has applied relatively little paint yet, there is already fine detail appearing in his underdrawings and tonal modelling.
Most artists used white gesso grounds, but the practice of adding pigment to them, at least in the final layers applied, wasn’t uncommon. When Velázquez was establishing his reputation before going to the Royal Court in Madrid, he followed standard practice among the provincial painters of the day in Spain, and used grounds which were usually deeply tinted with earth brown.
At other times, carbon black was added to generate black grounds, for example when the finished painting was going to use chiaroscuro. However, studies in the choice of colour for grounds have found many examples where there seems little or no correlation between the colour used and the subject, style or nature of the finished painting.
By the sixteenth century, some painters were reducing the number of layers of gesso and applying oil primings on top of them, often using lead white as a pigment in linseed oil binder, sometimes bulked out with an inferior white powder such as chalk. By the seventeenth century, many of those painting in oil on canvas had abandoned traditional gesso grounds in favour of thinner and simpler ‘oil grounds’ based on lead white and linseed oil. These could also incorporate other pigments to form different coloured grounds according to the painter’s preferences.
One of the characteristic techniques of the Pre-Raphaelites was the use of ‘wet white grounds’, in which oil paints were applied to lead white paint which had not yet dried. This was used by Millais in his painting of Ophelia (1851-2). To ensure that the white ground didn’t dry before coloured glazes were applied into it, it is believed that the Pre-Raphaelites painted small sections at a time. Some who tried this technique abandoned it because it proved too difficult, and all acknowledged that it made later corrections almost impossible.
The Pre-Raphaelites claimed that this technique was responsible for the bright and lustrous colours of their work, although others achieved similar effects without ever using wet white grounds.
In the latter half of the nineteenth century, changing painting style allowed some to apply the thinnest of grounds – usually oil grounds of lead white – to allow the texture of the underlying fabric to show through in the surface of their finished painting. Böcklin’s Sirens is unusual as he applied this same principle but for painting in egg tempera, which historically had almost exclusively been applied to the smooth absorbent surface of chalk and glue gesso.
Some artists used the thinnest of preparatory layers, or even applied diluted oil paint directly to canvas, as in József Rippl-Rónai’s study for a full-length portrait, which shows the fine texture of the canvas support.
Degas and some of his contemporaries developed an unusual if not paradoxical practice which they termed peinture à l’essence. Tubed oil paints can be a bit oily, and these artists experimented with reducing the amount of oil in their paints. Squeezing paint out of the tube onto blotting paper or rag and removing excess oil should not cause any problems, but peinture à l’essence took that to an extreme, in blotting out as much oil as possible, and restoring viscosity and flow by adding turpentine.
This was also used on very thin oil grounds, and in some cases it appears was applied to unprimed canvas.
Degas’ Danseuse dans sa loge (Dancer in her Dressing Room) (c 1879) is one of his experimental paintings which uses both pastel and peinture à l’essence applied to canvas. The detail view below shows how thinly he applied his paint to the ground, although it is impossible to judge how well it is adhering.
In the last couple of decades of the nineteenth century, and into the twentieth, avant-garde painters broke the last taboo in letting their ground show through. In Tom Thomson’s oil sketch of Tea Lake Dam, this was because of the speed at which the work had been painted over his ochre-tinted ground, here on a wood panel. Others, though, revealed their grounds in works painted more slowly and deliberately, even in the studio. What had once been a well-concealed secret was now on display to the world.
Other changes include the substitution of zinc white for lead white in oil grounds, now controversial in view of the tendency for zinc salts to saponify in the presence of water, and the introduction of acrylic grounds, often referred to incorrectly as gesso. The latter became common in commercially-manufactured canvases during the late twentieth century. Finally, oil grounds now sometimes use titanium and zinc white pigments in alkyd resins, which dry quickly and may prove even more durable than those using linseed oil binder.