Projection and Photoluminescence
More than 200 years before the camera was invented, Italian Renaissance artist Caravaggio (1571-1610) employed photographic techniques to develop his
renowned light and shadow paintings, according to Roberta
Lapucci, a teacher and researcher at Studio Art Centers
International (SACI) in Florence, Italy.
There is evidence to suggest that the 16th-century artist
and his contemporaries to some extent experimented with
optics – including lenses, the concave mirror and the camera
obscura – as aids in their creative process, Lapucci said. Caravaggio, for example, is known to have worked in a darkened
room and to have illuminated his models through a hole in the
ceiling, and he did not use preliminary drawings, she added.
Lapucci’s recent research, which she presented at the Brera
Museum in Milan in February 2009 and at the Collegio Ghis-lieri in Pavia in January 2009, both in Italy, provides evidence
that Caravaggio may have projected images onto a canvas
and used photosensitive materials to fix their outlines. The
process may have helped him to better portray the relationships between the models in a dramatic scene.
By the use of photosensitive materials such as mercury
salts, a permanent image could be produced within the darkened studio, which functioned as a camera obscura, Lapucci
said. “After the projection of the image, a luminous monochromatic simulacrum could remain visible on the canvas,
similar to a black-and-white photograph, for about 40 minutes to two hours – only in darkness; a light exposure could
have made it vanish,” she explained. “During this time,
within the darkened room, the painter could have fixed, with
a luminescent white paint, a monochrome (brown priming
and white paint) sketch of the projected figures.”
“To trace the main shapes of the highlights in his composi-
tion, Caravaggio used a lead white sketch, which seems to
confirm his attempts to block a snapshot composition on the
canvas before it vanished, or to assemble more figures to-
gether in a sort of patchwork,” Lapucci said, adding, “To fix
the poses of his models, he always traced some scoring.”
Lapucci said that there is a “Venetian white” paint that was
available in the 17th century that was made of 50 percent
lead white and 50 percent barium sulfate. “Its use by the
Venetian artists and by Caravaggio could be connected to the
camera obscura and should be viewed in this new perspective: as a fluorescent material which allowed the artist to
paint in the dark within the camera obscura,” Lapucci said.
Light-sensitive and photoluminescent substances were men-
tioned in the field of natural science by Giovan Battista Della
Porta, a 16th-century Italian scholar, scientist and playwright,
according to Lapucci.
These photoluminescent substances could be magnesium,
silver, mercury or arsenic, in combination with chlorine, sulfur and iodide. She added that salts of these substances could
be vaporized, nebulized or mixed to the priming components
(usually based on gypsum, animal glue, oil or pigment). She
said that nondestructive tests have been used to try to identify
these substances in the artwork but that these tests are limited: X-ray fluorescence, for example, identifies only heavy
metals and cannot recognize iodide, arsenic or sulfur.
“X-ray fluorescence did not find magnesium in Caravag-
gio’s artwork, and only a small amount of silver, but it did
detect mercury everywhere,” Lapucci said.
Lapucci said that, consequently, it can be supposed that
mercury is located in the priming layer. However, to position
mercury with certainty, cross sections (requiring destructive
testing) or a new kind of analysis would be needed – a sort of
x-ray fluorescence that scans for the presence of the element
micron by micron to understand where the mercury is located
and, consequently, whether the artist exposed the primed canvas to mercury vapors (such as mercury iodide), or mixed the
materials with the priming components, or applied these
materials over the priming as jelly emulsions.
Caren B. Les
Shown is an
x-ray image of
St. John the
from the artwork.
Background: Art historian Roberta Lapucci noted that there is a higher than
average number of left-handed models in works painted by Caravaggio
during an early stage of his career. This observation suggests that he may
have been unable to reverse the projected image from left to right with the
system he used at the time, she said. The photo represents Caravaggio’s
painting of St. Catherine.