Lectures are in the Play House: 10.45 for morning members: 13.30 for afternoon members.

Thursday 18 October 2018
Alchemy and Adventure: A History of Exotic Colours and Poisonous Plants.
Speaker: Lynne Gibson

COMPLETED – Late 2019 programme available mid 2019

This lecture explored how colours used in our most beautiful and valuable paintings were often poisonous and derived from alchemy. The colour red has been the most desirable through history. Pliny, the Roman, was said to have made the colour from the blood of two monsters; the elephant and a basilisk which was a mythical snake like dragon. The blood of both was supposed to have been combined together to form a red colour pigment ground into small particles and mixed with water to make paint.

Crimson was made from the parasitic insects on an Indian oak tree called kermes which were boiled and this gave off an acid. It was used to dye wool and silk. In Pompeii a bright orange red was used in mosaics which was made from Cinnabar; a costly and toxic mineral combining mercury and sulphur. Red lead was used in medieval manuscripts for the red lettering under an illustration. This was important lettering, usually a title, and thus the phrase “red letter day” came into being.

Roger Van der Weyde also used Cinnabar to paint St.Jerome’s cloak and this colour became known as vermilion. When mixed with oil, the pigment is protected from the atmosphere. The Virgin wears a bluey red cloak made from Cotswold wool. The cloth itself is called scarlet!

Van Eyck’s Arnolfini portrait shows the lady wearing a dress in scarlet green blue dye from Toulouse which was very expensive to produce so this colour is showing wealth. Raphael painted Pope Julius 11 wearing a silk cloak dyed in Kermes and this colour became known as Cardinal’s purple .The original recipe for this was lost so  whelks from Tyre were used, boiled with stale urine to make Tyrian Purple! The Romans were passionate about purple as it was so expensive to make and laws were passed proclaiming only the highest senators or imperial families could wear it. Cochineal was a better paint than Kermes but extremely expensive as it was made from the Coccus cacti insect found in Mexico and it required 2000 insects to make a gram of dye.

 Blue became an expensive dye for cloth and was represented on canvas by ultramarine made from lapis lazuli. This was ground up, mixed with wax and then flushed with water. Ground up gold leaf was used by Duccio as a background for the Virgin Mary’s cloak. The nearest cheaper pigment to gold was Orpiment but it had a high arsenic content in it so it destroyed the actual colour and any other colour near it. Turner and Vermeer used yellow ochre which was derived from the droppings of cattle fed mango leaves mixed with mud!

 Fortunately modern paints will be made from modern chemical dyes!