Last week, we were talking about oil paints and the media used to generate durable paintings. However, colour is really the important component of paint. It provides what we see and more importantly how we see it.
Some modern paints rely upon organic compounds synthesized in chemical laboratories. Tweaking the shape, size, and constituents in a molecule can modify the colours perceived.
But long before we had modern synthetic pigments, artists relied upon the earth around us to provide colours. Paints were made of finely ground minerals or metal ion containing compounds pulled from the earth. Indeed, all minerals are composites of cationic metal ions and some anionic component such as sulphides, oxides, carbonates, or other species.
The richness of colours obtained from metal ions is seen in the names of the elements. Chromium, for example, provides a wide variety of different colours depending upon what anion is present. It is a chameleon, able to take on a variety of hues.
If we go far enough back in history to the cave walls of Altimira and Lascaux, we find there red and yellow pigments obtained from the iron oxide haematite crystallized with varying numbers of waters of hydration. Modern versions of these pigments can be seen in rusted metal which can range across the reds and yellows, and can be altered by the simple process of heating. The browns the cave painters used were derived from manganese oxide while the greens came from the aluminosilicate clays celadonite and glauconite. White was available from chalk or calcium carbonate but also from ground up dried bones which are a mineral called hydroxyapatite.
All of these colours are inorganic and permanent, which is one of the reasons the artwork has stood the test of time. The only organically derived component of cave paintings was the charcoal used to provide black lines. Carbon is intrinsically black and not susceptible to simple oxidation so it was a suitable and long lasting pigment.
Essentially, our ancestors in Europe had available a palette consisting of red, yellow, black, and white, which is common to most ancient cultures. They had a few extra colours in the greens and browns but they worked with a very limited palette.
Because they were working in primitive conditions and with these primordial hues, it is easy to dismiss the artistry and ingenuity that went into these cave paintings. Yet they have lasted over 30,000 years and provide a record of life long before the written word.
The paintings also demonstrate a sophisticated understanding of both colour and the methods of painting. Our artistic ancestors ground up haematite into a fine powder in a mortar-and-pestle-like apparatus. They mixed it with a binding medium, such as vegetable oil, and in at least some locations employed spray painting techniques by perhaps blowing paint from a hollowed out reed. They left behind incredible outlined handprints on the walls much as you might see in an elementary school classroom today.
Around 12,000 years ago, the artists at the Niaux caves of the Pyrennes devised new methods. By adding neutral materials called extenders, they were able to make their precious pigments go further while also improving the properties of the paint itself. A similar process is employed in any modern paint store where a neutral white paint is tinted by the addition of colour prior to purchase.
They also discovered they could alter their pigments. For example, the addition of potassium feldspar to haematite red results in a darker, richer colour and a paint which is less prone to cracking. A better recipe was obtained some 1,500 years later by the addition of biotite to the feldspar extender.
These early artists didn't just copy the techniques of their predecessors. They experimented with different materials and explored new methods. The one thing they didn't do was come up with a very good version of blue.
These ancient artists principally relied on physical modification of their stock material. Grinding stones into powders and mixing the resulting pigments to make colours was about the limit of their abilities. However, eventually, they learned to employ the single transformative agent they had available - fire.
Heat is a powerful agent. It has been argued our modern dentation and the structure of our skulls with our comparatively large brains would never have evolved if we hadn't learned how to tame and utilize fire over a million years ago. But in order to use heat to create new pigments, the temperature had to be much hotter than provided by an open flame.
It wasn't until the rise of modern city states in Babylonia and Assyria that furnaces capable of transforming colours were built. Invariably every culture around the world developed a richer artistic palette as they experimented with the generation of higher temperatures.
More on the development of pigments next week.