Among the things archaeologists have found in Pompeii are little bowls of painters' pigments.
These have been found in several houses, all of which seemed to be undergoing restoration or redecoration.
They have been studied for a long time, but early investigations were uncertain and contradictory. Now there is
a new study from a bunch of Italian chemists who used both powerful microscopes and spectoscopy to study numerous samples.
The main finding is the complexity of some of these mixtures, and also their diversity, with different mixtures producing the same or similar colors. The authors also observe that besides the mixing that took place before the fresco was painted, pigments were also mixed by being applied in multiple overlapping laayers.
It is reminder of the astonishing riches of Pompeii, which holds more knowledge of the past than ten thousand ordinary archaeological sites.
The main finding is the complexity of some of these mixtures, and also their diversity, with different mixtures producing the same or similar colors. The authors also observe that besides the mixing that took place before the fresco was painted, pigments were also mixed by being applied in multiple overlapping layers.
ReplyDeleteGiven that the Romans didn't have chemistry, and didn't make decisions based on the chemical compositions of rocks and minerals, rather than just... their color... this is hardly surprising.
Ancient pigments are stupendously simple. You take a colorful rock. You grind it up into powder. Whatever color it is as a powder is more or less what color the paint will have, once you mix the powder into a liquid binder like oils. If you desire a different color than any of the powders you already have, you start combining powders of different colors.
If you have a shade of blue and want a lighter blue, you combine it with a whiter powder. If you want a darker blue, you combine it with a blacker powder. If you want more of a blue-green, you add green powder. It's basic color theory stuff. You start with a limited set of colors, and make more by combining them in different proportions. You don't give any thought to the chemical makeup of any of them, you just eyeball it and experiment.
That’s not really how color mixing works with pigments. If you want a lighter blue, you have to find a pigment that is lighter blue. Mixing white pigment in gives a pastel blue at best, and dull gray more probably. It’s a good way to ruin the expensive blue pigment you have managed to acquire.
DeleteA better approach would be to thin the pigment in a binder and apply as a wash or glaze, distributing the particles of pigment across the surface/canvas.