The vegetal pigments used in botanical illustrations


Plants that provide colorants have always played an important role in artistic techniques, contributing to their development and perfection.
The introduction of colour increased the artistic value of botanical engravings, which were considered not only as illustrations but also as works of art. The colour of the flowers aided in identifying medicinal plants. Natural colorants were extracted from plants using maceration or machination: the most important quality of the colorants was to be resistant but not too acidic, so as not to damage the paper.

Blue pigments were obtained from woad (the common name for Isatis tintoria), a plant known since antiquity also for its medicinal properties and spread across Europe. In Italy it was cultivated predominantly in the Marche. In the area around Aboca woad was used to dye cloth made in Florence.
Its blue was often substituted by indigo, which was extracted from Indicofera tintoria, a plant from India that gives a very stable and concentrated pigment.

The most commonly used greens were given by the pigment extracted from the sap of iris flowers, which, though blue to look at, give off a brilliant green substance when crushed in a mortar. A dark green, however, was extracted from the berries of rhamnus.

The most popular yellows were obtained from extracts of turmeric or saffron. Both these oriental spices were also widely used in cooking.

The most resistant of red pigments come from Brazilian red wood (Caesalpina brasilensis) and domestic madder.

Blacks were obtained from vine black. This was prepared by burning vines or very resinous woods in special ovens, then collecting the black ash from which the pigment was made.