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.1 It is a biennial and grows up to five feet in height. The long spikes with small pale yellow flowersbegin to appear in early June, and attract bumble bees and other insects. Weld was used for dying silk and woolen materials long before ti was used for making oil 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.

Reseda luteola
Reseda luteola
is a plant species in the genus Reseda. Common names include dyer's rocket, dyer's weed, weld, woold and yellow weed.

"Weld belongs to a class o pigments called lakes which, unlike earth pigments, are organic in origin made from plants or insects. Lakes have very little bulk and need to be processed so that they can be transformed into a paste suitable for oil painting tehcnique. However, the coloring component for lakes could be obtained from sheerings of dyed cloth or other textile waste as well as from the raw materials themselves. The soluble dyestuff components extracted from organic substances were then converted into the insoluble lake pigment by the addition of alum. In the case of yellow lakes, some form of calcium carbonate, such as chalk, was frequently a major ingredient. Lake pigments have a long history in decoration and the arts. Some have been produced for thousands of years and traded over long distances. Yellow lakes were often used in a more unobtrusive manner than for coloring yellow object: it was mixed with a variety of blues to give greens and duller yellow pigments, such as a yellow earth, more life." 2

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."3 Identifying the dyestuff used in a lake pigment can be problematic as it may be present in very small amounts.

The Love Letter (detail) by Johannes Vermeer
The Love Letter (detail)
Johannes Vermeer
c. 1667–1670
Oil on canvas, 44 x 38.5.cm.
Rijksmuseum , Amsterdam

It is likely that Vermeer used weld in other paintings as well. Perhaps the exquisitely modeled satin gown of the seated mistress in The Love Letter was glazed with weld over a monochrome light brown or lead-tin yellow underpainting.

In a recent analysis, a large amount of chalk, along with the base lead-tin-yellow pigment, was detected in a paint sample taken from the yellow sleeve of The Guitar Player. The chalk most likely was employed in the preparation of the yellow lake pigment which has now markedly faded.4 The garment, thus, may have been originally more strongly colored that it presents itself today.

  1. Dyes are molecular coloring substances that normally require mordants so that the color will deeply penetrate the textile or hair fibres The color is applied by immersing the item being dyed in the liquid colored substance. The dye "color"' by staining the object being colored and penetrating beneath the surface.
    from: "Paint characteristics Paint, inks and dyes," Paintmaking.com. http://www.paintmaking.com/characteristics.htm
  2. Helen Howard, David Peggie and Rachel Billinge, "Pigments," Vermeer's Palette, National Gallery website. http://www.nationalgallery.org.uk/paintings/research/meaning-of-making/vermeer-and-technique/vermeers-palette#yellowlake
  3. Scientific Examination of Vermeer's "Girl with a Pear Earring," Karin M. Groen, Inez D. van der Werf, Klaas Jan van den Berg, and Jaap J. Boon, in Vermeer Studies, eds. Ivan Gaskell and Michiel Jonker, National Gallery of Art Washington D.C., New Haven and London: Yale University Press, 1998, 175.
  4. Helen Howard, David Peggie and Rachel Billinge, Vermeer's Palette, "Pigments," National Gallery website. http://www.nationalgallery.org.uk/paintings/research/meaning-of-making/vermeer-and-technique/vermeers-palette#yellowlake