The right light can save art
The technology that applied to lighting helps to keep the ancient paintings longer.
The main enemies of the works of art are the external agents that damage them. Looking closely at a painting, for example, cracks can be seen on the surface of the canvas, especially if the painting is very old. This damage is caused by light, by radiant energy that hits the surface of the painting and causes irreversible damage to the work of art.
However, all is not lost. A research, published in The Journal of the Illuminating Engineering Society, shows how through the optimization with intelligent lighting systems it is possible to drastically reduce the damage to the paintings, preserving their chromatic aspect.
The dilemma: usability of the works against safeguarding
The problem of injury to works of art caused by infrared, ultraviolet and visible radiation (light) is well documented. When a photon (a particle of elemental light) is absorbed by a paint pigment, the pigment molecule rises to a higher energy state and the chemical composition of the molecule changes. What happens is called photochemical action.
Viewed from a human point of view, the photochemical action is manifested by cracks, discoloration or surface hardening.
Daylight, which includes infrared and ultraviolet radiation, is highly harmful to paintings. In museums, it is common practice for lighting to use incandescent diodes and, more recently, light-emitting diodes (LEDs), to reduce damage.
However, a team of researchers has shown that light can cause color degradation regardless of lighting technology. The bright yellow colors in Van Gogh’s famous Sunflowers are turning dark brown due to the absorption of blue and green light from the LEDs. Research into the conservation of works of art makes it appear that this is a lost battle.
One might think that the best method of preserving the paintings is the complete absence of light, but we need light to appreciate the beauty of these works.
This leaves us with a dilemma: visibility or harm?
The solution is to optimize the light
Lighting technology itself may not be enough to deal with this dilemma. However, the way we use technology can make a difference.
According to the University of Sydney, this problem could be addressed with an approach based on three key facts:
light triggers photochemical actions only when it is absorbed by a pigment
the reflectance factor of a pigment, i.e. its effectiveness in reflecting light, determines the amount of light absorption
the light power, i.e. composition of the light spectrum and light intensity, of lighting devices, such as LEDs, can be precisely adjusted.
It is possible to measure the reflectance factor of a painting and optimize lighting to reduce absorption. Results of some research have shown that optimizing light to reduce absorption can significantly decrease energy consumption and without loss of visual experience. Objects look equally natural and attractive under optimized light sources compared to normal white light sources.
In this new study, we optimized the LEDs for five paintings to reduce light absorption. By using a genetic AI algorithm, light absorption can be reduced by between 19% and 47%. In addition to the benefits for painting, this method has also almost halved the energy consumed by lighting.
In addition to greater sustainability and conservation of the art, the color quality of the paintings was another parameter that was held up against in this optimization process. The chromatic aspect and brightness of the paintings have been kept constant in order not to reduce the appreciation of the work of art. This happening happens because of an oddity in our visual system. Photoreceptor cone cells, the cells of our retinas that allow color vision, are not equally sensitive to the entire visible spectrum.
Different combinations of wavelength and intensity can cause identical signals in our brain. This allows some flexibility in the use of different light sources to facilitate identical color aspects.
This intelligent lighting system requires scanning the graphics to obtain color information. Thus, a projection system accurately emits light optimized for painting.
This method offers a solution to extend the life of works of art, without the need to leave them in the dark.