Chemical techniques in the service of art. Researchers have analyzed UNED Paleolithic paintings in the caves of Tito Bustillo and El Buxu (Asturias) to determine its composition. The study reveals that its main component is the mineral hematite and the grain of the pigments are so fine as the one used today.
“It is surprising that the grain size of pigment found in some paintings of the cave of Tito Bustillo is similar to that used today,” says Antonio Hernanz, researcher at the Department of Science and Technology, UNED Physicochemical and author of the study.
Science, UNED, University of Castilla la Mancha and University of Alcala de Henares have analyzed the composition of different localized Paleolithic cave paintings in the caves of Tito Bustillo in Asturias and the Buxu.
The main component have found that hematite is the mineral, with three granular size: less than one micron to 10 microns and 30 microns. “They’re very small sizes, and the finer the grain, the greater the power of paint to cover a surface,” says Hernanz.
The study, published in Journal of Raman Spectroscopyreveals that the oldest representations (belonging to the Aurignacian culture, with an estimated age of 30,000 years) have a smaller grain than the rest, less than one micron. This size suggests that “the oldest paintings we have used a technique developed to prepare the pigment,” adds the researcher.
Spectrum of the sample
The study was made possible by the use of different microscopic and spectroscopic techniques. This results, images of the microparticles which are the pictorial material, sets of signals (spectra) to identify chemical and mineralogical composition.
With these tools, experts have been able to confirm that the red color of the paintings was produced with hematite, a mineral consisting of one form of iron oxide. They also found hydroxyapatite, another mineral that makes up bones, suggesting that the paint is added small amounts of charred bones, associated perhaps with some kind of ritual.
The darker motives were achieved by adding pigments to the paint as the mineral wüstita (another iron oxide), charcoal and manganese compounds. As fillers (complementary), Palaeolithic artists used calcite, quartz and clay minerals. We also found anatase (a titanium oxide) in two of the pictographs.
It so happens that in the cave of Tito Bustillo there is a deposit of ocher, a clay material rich in hematite. However, the study, this was not used ocher for paints. “They had to use other veins or deposits of red pigment than those that arise in the cave itself,” the investigator at the UNED.
In the shadow of Altamira
The discovery of the paintings of Altamira in 1879 was the first proof of the existence of Paleolithic art in the Cantabrian area. To date, we have cataloged over a hundred caves with paintings of this extended period, among which are Tito Bustillo and El Buxu, located in the Asturian municipalities and Cardes Ribadesella respectively. The residents of these areas drew abstract signs or animals of the Ice Age.
Tito Bustillo, discovered in 1968, is considered one of the jewels of this art, surpassed only by Altamira. Its walls are decorated with hundreds of representations of animals and symbols. The Main Panel is the most important houses of the cave and overlays that can extract a diachronic sequence. For example, there are depictions of horses in shades of black, red and purple. The dating of these reasons stands at between 14,000 and 10,000 years ago.
The Cave of The Buxu, discovered in 1916, recorded shows on the walls of a bison, wild goats, horses, deer, schematic signs (painted, plus prints). According to Mario Menendez, a researcher at the UNED and coauthor of this study, the representations in question could have been made between 17,000 and 14,000 years ago.
Antonio Hernanz, Joseph M. Gavira-Vallejo, Juan F. Ruiz-Lopez, James Martin, Angel Maroto-Valiente, Rodrigo de Balbin-Behrmann, Mario Menendez, Jose J. Alcolea-Gonzalez. “Spectroscopy of Palaeolithic rock paintings from the Tito Bustillo Caves and The Buxu, Asturias, Spain.” Raman Spectroscopy Journal of , November 2011. DOI: 10.1002/jrs.3145.
|Category: Chemistry||Tags: Palaeolithic caves|