Compared to oil painting, pastels required less time and fewer tools, but the application of the colors was complex and making corrections was difficult. Pastels are most often executed on paper, though vellum was occasionally used for portraits of royal sitters, such as those by Jean Étienne Liotard (Swiss, 1702–1789). The paper used was usually the same type made for wrapping objects; it was relatively strong and coarse and thus well suited to withstand rubbing with pumice, a technique that artists used to produce a weak bond, or tooth, to hold the pastel powder to the support. These papers were generally blue (the color was rarely left visible because the sheet was fully covered with pastel) and they were mounted on canvas tacked to a strainer to provide a good working surface.
The tools of the pastelist were basic, the most important being stumps, or tight spirals of paper or leather—or simply the artist’s finger—that were used to spread the pastel powder. Most portraits were executed with dry pastel, the artist either stumping or “sweetening” the color into smooth continuous masses without ready evidence of individual strokes, as in the example of Jean Marc Nattier’s portrait of Madame Royer, or with a network of discrete strokes that the eye would optically blend, as in Jean Baptiste Greuze’s portrait of Baptiste aîné.
Many artists also incorporated wet techniques: either using pastel powder mixed with water or a gum and applying it by brush or blending it with the finger (as in Rosalba Carriera’s Young Woman with a Pearl Earring) or wetting the tip of the pastel and applying it thickly to create an impasted effect comparable to oil, as seen in the lace details of John Russell’s Portrait of Mrs. Robert Shurlock and Her Daughter Ann.
In the portrait of Lady Rushout and her children, Daniel Gardner employed a distinctive mixed-media technique using pastel for the flesh tones and watercolor and broad thick strokes of gouache for the background and clothing. The overall effect of these works, rendered as if by brush and surrounded by a gilt frame, succeeded in evoking the presence of an easel painting.