Weld

(schijtgeel)

Origin, History and Characteristics

Weld (in Dutch, wouw or woude) is a natural dyestuff obtained from the cultivated plant Dyer's Rocket, a tall growing relative of the garden mignonette. It is the oldest European dye plant in the world. The color of weld is derived from the flower of the weld plant. Weld was used for dying silk and woolen materials as well as for making paints. Since weld is soluble in oil it must first be precipitated onto alum and then kneaded with chalk to give it bulk. Since weld is very transparent it is and ideal pigment for glazing.

Dyer’s mignonette or weld produces an outstanding primary yellow on all protein fibers and cotton. This yellow is clear and intense, the yellow that all other yellows are judged against. The substance responsible for producing this color is luteolin and is present in all the green parts of the plant. Compared to other plant sources for yellow available to the home dyer, weld is very concentrated. Six or seven weld rosettes or two weld plants in bloom will dye a pound of wool an intense primary yellow color.

Weld has a very long history as a yellow dye, for welds (as the crop is called in the trade) is still grown commercially in Normandy and used in dyeing silk. No synthetic dye has been able to replace it in this function. The whole plant, flowers, stems and all, is dried and sold in bundles, and for dyeing and color-making it is broken up and stewed in water or a weak solution of alum. Medieval color-makers considered weld lakes with high esteem when opaque, and preferred buckthorn for transparency. Sometimes weld lakes were precipitated on a base of egg-shells, sometimes on white lead. When white lead was used, the color was a pure, light yellow, as brilliant as orpiment.

Weld in Vermeer's Painting

Weld has been detected only once in Vermeer painting during a recent study of the Girl with a Pearl Earring. In the 1994 restoration of the painting it was discovered that Vermeer had glazed the whole background, initially painted in black, with a mixture of indigo and weld which together, produced a deep transparent green. Both pigments are adapted for glazing since they are very transparent. The background of the painting was originally a smooth, glossy translucent hard green paint. Vermeer probably wanted to convey "a perfect illusion of a precious object made of enamel." 1

It is likely that Vermeer used weld in other paintings. Perhaps the exquisitely modeled satin gown of the seated mistress in the Love Letter was glazed with weld over a monochrome underpainting. Its color is appreciably different that the typical yellow lemon (lead-tin yellow?) of the jacket worn by the same sitter and has a depth that denotes glazing.