Painting technique
From the early 18th century, “color men” appeared on the scene to provide artists with ready-made paints. Watercolor painting also became a fashionable pastime among the wealthy. In 1766, William Reeves set up a business supplying watercolor cakes. Reeves’ watercolors were a significant improvement on those of his competitors, since he discovered that the addition of honey to the colors prevented the cakes from cracking in storage. In 1783, the wigmakers Thomas and Richard Rowney abandoned the declining wig trade and began preparing and selling artists’ colors. Constable and Turner were among the famous artists they supplied with materials.
Palette
In terms of artist colors, the 18th century was the watershed between the traditional color palette of the Renaissance and the new palette of the modern era. That said, many of the advances in color chemistry that took place in the 19th century were based on research conducted in previous years. Therefore, early 18th century oil painters - painting in the late Baroque, Rococo, or Neo-Classical art styles - were still using the basic color palette of the Renaissance era and there were only two primary new pigments in the 18th century color palette: Prussian blue and cobalt green.
Sir Joshua Reynolds (1723-1792)
Sir Joshua Reynolds dominated English artistic life in the middle and late 18th century and he drew British painting toward the continental Grand Style.
Today many Reynolds’s portraits show pale faces. It’s known that even in his lifetime his paintings began to fade. Using transparent glazes over a monochrome under painting, he tried to reproduce the effects of Italian old masters, but the pigment he used for his flesh tones was not permanent and faded. Furthermore, in the 1760s, Reynolds began to abundantly add coal substances to pigments, producing still more unstable paints.
Although too fond of varying his practice by the introduction of many dangerous compounds, and by the use, in the same picture, of incompatible media and methods, Sir Joshua Reynolds executed many works between the years 1770 and 1775. He restricted his palette to seven colors: lead white, yellow ochre, ultramarine, orpiment, carmine lake, Naples yellow, and vermilion.