We didn’t get time to ask all the #SciCulture Twitter question on the April show. But never fear, Mark Bockrath has taken the time to answer all the questions for the blog. And some of the answers are quite strange. Who had any idea that mango-leaf chewing cows were used to make a pigment?
If you missed “Alchemy’s Rainbow: Pigment Science and the Art of Conservation,“ you can watch it here.
A: Many modern pigments are more stable than older pigments of similar color, but not all. Some modern paintings are painted with dyes and fluorescent pigments that fade faster than many old pigments.
A: Earth colors such as ochres, umbers and sienna. Also, most mineral pigments, natural or artificial, like cinnabar, cobalt colors, ultramarine, cadmium and chrome colors are stable. Titanium and zinc whites are quite stable. Dye-based and organic pigments are the least stable.
Q: Arcanian@GrandArcanian: How does the type of oil used affect the paint? What other oils can be used?
A: Linseed is the most important oil historically, but poppy oil, walnut oil, safflower oil and other drying oils have been used. The latter oils were used to avoid the yellowing of linseed oil but they often don’t form as durable a film as linseed oil. Softer oils may lead to damage to the paint film when it is cleaned; oils that yellow will darken the painting’s color.
Q: Patricia @Hard2get_who was the most famous alchemist to make pigments? Newton? Boil? Brahe? Aristotle?
A: I don’t know this one.
Q: Kevin Brandon@Kev_nBrandon How much was known about UV light dulling colors and what was done to prevent it if anything
A: People have known for centuries that light fades paintings, fabrics, etc., even if they didn’t know that the UV portion of the spectrum is the biggest cause of the damage until perhaps the mid 20th century. In the past, materials that faded easily were kept out of direct sunlight, were covered with curtains attached to frames, or kept in closed albums (esp. watercolors).
Q: Patricia @Hard2get_isnt there a really rare yellow that comes from a plant only found in vietnam?
A: I can’t think of one.
Q: Arcanian@GrandArcanian Did pigment availability have an effect on the development of painting techniques?
A: For most European painters since the Renaissance, a wide array of similar pigments were available throughout Europe, so a French painter was not restricted to a different palette than an Italian painter. However, as each new pigment was developed and found widespread use, palettes changed from period to period. The use of drying oils like linseed oil didn’t change much after oil painting became important in the 16th century. The technique of oil painting changed mostly as a result of stylistic choices–early painters using the oil medium thinly and in a detailed manner almost like earlier tempera layering (Van Eyck), and later painters using thicker paint and looser handling (Rembrandt). Artists could only choose from available pigments, so Old Master painters made do with duller yellows and mixed greens, unlike the Impressionist painters, who had so many newly-developed bright yellows, clear greens and blues and violets than had ever been seen before, so this allowed them to paint with much greater brilliance of color.
Q: Arcanian@GrandArcanian Were certain regions/countries better at producing a certain pigment than others?
A: Yes, especially pigments that were found in ores that were plentiful in certain areas-ultramarine blue from Afghanistan, graphite from England, umbers and sienna from Umbria and Sienna areas in Italy, which had particularly fine deposits of those pigments. Many of these pigments are found world-wide, but some countries had especially rich deposits or had been mining them for long times before they were found elsewhere. Also, some countries had pigment industries that were very particular to their location- mummy brown is only from Egypt, cochineal was made from red insects found in South America after it was colonized, and Indian yellow was produced from Indian cows fed on mango leaves (until it was prohibited in the 20th century).
A: Earth pigments were comparatively inexpensive, as were some dye-based colors made from local plants. Natural ultramarine blue was extremely expensive because of transportation costs, as it was found in large deposits in Afghanistan. Manufactured pigments like litharge, white lead orpiment were more expensive than earth colors. Minerals like cinnabar that needed to be refined were costly. For most European painters in early modern times, the earth colors, some dyes, the refined mineral pigments and manufactured pigments were widely available for purchase. The farther away the source of the pigment, the more it cost.
(Image from Wikimedia Commons)