An Artist’s Secrets?
Projection and Photoluminescence
More than 200 years before the camera was invented, Italian Renaissance artist Caravaggio (1571-1610) employed photographic techniques to develop hisrenowned light and shadow paintings, according to RobertaLapucci, a teacher and researcher at Studio Art CentersInternational (SACI) in Florence, Italy.
There is evidence to suggest that the 16th-century artistand his contemporaries to some extent experimented withoptics – including lenses, the concave mirror and the cameraobscura – as aids in their creative process, Lapucci said. Caravaggio, for example, is known to have worked in a darkenedroom and to have illuminated his models through a hole in theceiling, and he did not use preliminary drawings, she added.
Lapucci’s recent research, which she presented at the BreraMuseum in Milan in February 2009 and at the Collegio Ghis-lieri in Pavia in January 2009, both in Italy, provides evidencethat Caravaggio may have projected images onto a canvasand used photosensitive materials to fix their outlines. Theprocess 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 dark-
ened studio, which functioned as a camera obscura, Lapucci
said. “After the projection of the image, a luminous mono-
chromatic simulacrum could remain visible on the canvas,
similar to a black-and-white photograph, for about 40 min-
utes 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 perspec-
tive: 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 couldbe vaporized, nebulized or mixed to the priming components(usually based on gypsum, animal glue, oil or pigment). Shesaid that nondestructive tests have been used to try to identifythese substances in the artwork but that these tests are limited: X-ray fluorescence, for example, identifies only heavymetals and cannot recognize iodide, arsenic or sulfur.
“X-ray fluorescence did not find magnesium in Caravaggio’s artwork, and only a small amount of silver, but it diddetect mercury everywhere,” Lapucci said.
Lapucci said that, consequently, it can be supposed thatmercury is located in the priming layer. However, to positionmercury with certainty, cross sections (requiring destructivetesting) or a new kind of analysis would be needed – a sort ofx-ray fluorescence that scans for the presence of the elementmicron by micron to understand where the mercury is locatedand, consequently, whether the artist exposed the primed canvas to mercury vapors (such as mercury iodide), or mixed thematerials with the priming components, or applied thesematerials over the priming as jelly emulsions.
Caren B. Lescaren.email@example.com
Background: Art historian Roberta Lapucci noted that there is a higher thanaverage number of left-handed models in works painted by Caravaggioduring an early stage of his career. This observation suggests that he mayhave been unable to reverse the projected image from left to right with thesystem he used at the time, she said. The photo represents Caravaggio’spainting of St. Catherine.
Shown is anx-ray image ofCaravaggio’spainting TheBeheading ofSt. John theBaptist andcross-sectionanalyses takenfrom the artwork.