Thursday, December 15, 2011

Ultramarine Blue

Author Eve Ashcraft, in her informative book I recommended a few weeks ago, gives more information about early painters' steps necessary to obtain precious and expensive colors.

"For centuries, color---and the pigments to create it---was as precious as gold. Imagine if I, as a color expert, held the secret formula to the perfect sky blue paint and, to my colleagues' chagrin, only my clients could have access to that hue for their walls.

This kind of scarcity and level of secrecy was once common in the world of color. Artists would go to great lengths to protect and keep secret their color formulations. Costly pigments were held under lock and key. Even the most prominent artists relied on wealthy patrons to front them the money to procure expensive pigments. For example, if Vermeer had a client who commissioned a painting containing a certain amount of costly ultramarine blue (lapis lazuli, ground as pigment) that patron would have to advance the money so the artist could buy the precise amount of the pigment needed. And, Vermeer would have to accept visits from financial auditors who would make sure that the pigment was being used as contracted and that none was being squirreled away by the artist or his helpers."

Vermeer's 'Girl with the Pearl Earring,' also called 'The Mona Lisa of the North' pictured above included the vibrant ultamarine blue in her face-framing turban or scarf. The color sets off her skin tones very beautifully.

Today we artists are privileged to have at our fingertips almost any color at a relatively affordable cost. I will never gripe about the cost of paint or art supplies again.

On another note, just wanted you to know the difference in angels depicted in old paintings.

Cherubs are those portrayed as  winged infants with  chubby, rosy faces. They are depicted in western art from the 15th century onwards.  Putto, "little boy" in Italian, is the chubby, naked child represented in art since classical times, often as a decorative feature. Often, putti are adorable, cherubic heads with wings and no bodies.

 by Raphael

 Originally derived from ancient representations of Eros, the Greek god of love, since the Renaissance putti have often been associated with his Roman counterpart, Cupid. Cupid is normally represented as a naked, winged boy with bow and arrows.

From: The Concise Oxford Dictionary of Art Terms.

Tuesday, December 13, 2011

Luxurious Lapis Lazuli

Taken as a whole, lapis lazuli means "stone of L─üzhward/Afghanistan".
The name of the place came to be associated with the stone mined there and, eventually, with its color. The English word azure, the French azur, the Italian azzurro, the Polish lazur and the Spanish and Portuguese azul are cognates.  From Wikipedia

I recently heard a wonderful lecture given by Brian Baade, "Secrets of the Old Masters," at the Philbrook Museum of Art. He is a painting conservator and artist. He not only analyzes, but actually reconstructs paintings using historically accurate techniques.  I found the history of lapis lazuli especially intriguing.

Freshly mined and polished Lapis Lazuli, an opaque amalgam of minerals, is a magnificent blue, prized for millenia. Ground up and mixed with linseed oil, early painters used this magnificent hue to designate the Virgin Mary by painting her cloak this signature color. Christ is also depicted during his earthly ministry wearing a blue cloak.

This pendant was made in Mesopatamia 3900 BC. Highly prized and enormously expensive,  lapis jewelry became status symbols worn by the wealthy.

Mined in Afghanistan for centuries, it has always been rare and expensive. Pre-Renaissance painters' cities had to buy the mineral and keep it safely stored. If a painter received a commission to depict the Virgin Mary and infant Christ, for instance, the contract between the artist and his patron was shown to the magistrates who apportioned the lapis to the artist. Because it was so precious, perhaps costing $10,000 per pound, the artist put an undercoat of cheaper color under the lapis. Through time, some brilliant blues have oxidized into darker blue shades.

Egg tempera painted on wooden panels seemed to preserve the brilliance of the color. Southern European artists usually used poplar wood for panels, northern ones used oak panels. Lapis varies from azure-blue to deep-blue gemstone of lazurite.

Today, this magnificent color has been produced synthetically, like all earlier, costly colors, making it accessible to painters everywhere.

Thursday, December 8, 2011

Do Animals See Colors?

Can our fellow creatures see colors the way we can? I have pondered that question awhile. The following article and pictures supply the information thoroughly.

By Dr Ivan R. Schwab

 Dogs see colors, but their span of color vision closely resembles the array of colors seen by “color blind” males.
About 8%, or 1 out of 12 males (humans) and about 1 out of 200 females are “color blind.” We use that term to describe individuals who are color deficient, but they are not truly color blind. The eye has cells that perceive color and these are called cone photoreceptors or “cones.” We use another set of photoreceptors called “rods” for the black and white vision of dim light or nighttime. Our cones contain three visual pigments each of which responds to a different spectrum of wavelengths of light. It is these three visual pigments that combine their signals to permit us to have color vision by blending the signals, depending on the wavelengths received. Although it is an over-simplification, and misleading to some extent, we can describe our visual pigments as blue, green, and red. The brain receives the input from these three channels and then interprets the color we see. At least two different color channels are needed for color vision because the brain needs to “compare” these two different channels to determine color.
Color blindness in humans is caused by the genetic deficiency or loss of either the green or the red photopigment hence that input into the brain. So, the brain learns to see only those colors that can be interpreted or constructed by combining the input from the other two remaining visual pigments. The result is a less robust spectrum of colors, but colors are still seen. True color blindness in humans does exist when two of the three visual pigments are genetically unavailable, but it is exceedingly rare. If only one visual pigment channel is coming to the brain, say the blue cone input, it isn’t seen as blue but rather as on or off—hence that is “real” color blindness and would be a black and white world.
So, almost all color blindness in humans is not true color blindness but would be better described as color deficiency.
Now, let’s go back to your dog. Normal dogs have two different visual pigments in their cones, and much like humans afflicted with so-called “color blindness.” But they would see color. The color input would be weaker to some extent because dogs have fewer cones than we do because they are evolutionarily closer to their nocturnal ancestors. Cones are needed less, if at all, at night.
So, what about the other pets in the household? Your cat will have a similar color distribution as your dog although there are some subtle differences.
Birds, on the other hand, possess rich color vision, in many cases better than our own. Most birds have four cone visual pigments, although this varies. In general, birds have an additional ultraviolet pigment in their cones and many more cones than we have. Furthermore the visual pigments that would be similar to ours span different wavelengths. Their visual experience is richer than our own in ways impossible to describe or understand. Not only do they see more colors, but the interpretation of colors would be different. Think of combining different colors of paint—if you combine more colors radiating from the same object, like a flower, you will see different colors. A hummingbird, then, would see a red flower as a different color because of the ultraviolet channel input.
You may ask what good are these extra color channels in birds? Of course, it’s hard to know completely since we can’t even understand the perception of the color “ultraviolet,” but here is an example. When a mouse is being hunted by a hawk, it will often urinate out of fear and to make itself as light as possible for escape. Mouse urine radiates ultraviolet and that actually helps the hawk follow the mouse trail. Fresher urine radiates more ultraviolet light. The ultraviolet arrow will point to lunch for the hawk.
For those of you who have aquaria, the story gets even more interesting. There are at least 28,000 species of fish on earth, not to mention the staggering number of invertebrates. Although no one will have that large of an aquarium, commercially available animals for aquaria are quite numerous and it is harder to generalize about them. Many fish have four visual pigments or channels and, like birds, even the three that would resemble our own, span different wavelengths and provide more robust color vision. That is a very different story.
Hence, the answer to the question of “Does my dog see in color?” is “yes” although not as well as you probably do.
The next question you might ask is “Does my octopus sees in color since it can change into so many different colors?” Surprisingly, the answer is no, because octopuses have but one visual pigment. But that is a story for another day.
Dr. Ivan R. Schwab, a professor at the University of California, Davis, is the author of Evolution’s Witness: How Eyes Evolved. He also has a blog which you can find here.