Elsa Arroyo

Non Destructive In Situ Study of Mexican Codices: Methodology and First Results of Materials Analysis for the Colombino and Azoyu Codices

Little is known about manuscript writing and painting practices in pre-Hispanic Mesoamerica. Around the world, only 16 codices from pre-Hispanic Mexico survived the Spanish conquest, most of them preserved in European collections. Even though the manufacture of codices was widespread during the post-Classical period (1325–1521 AD), the features of the surviving pre-Hispanic and Early Colonial documents show some technical differences that can be related to local traditions. The only pre-Hispanic codex held at a Mexican Collection is the Colombino Codex from the Mixtec coast in the south of Mexico. Nevertheless, many manuscripts produced in New Spain preserved the indigenous codices traditions and practices. These manuscripts are an outstanding information source in terms of the materials used in the writing and colouring traditions. Usually, organic colours obtained from local plants and carbon inks on calcium-rich preparation layers were employed. However, there are few studies of original manuscripts, carried out on a limited number of samples (Gonzalez Tirado 1998), and scarce information has been made available on this subject to date.

The Grolier Codex: A Non Destructive Study of a Possible Maya Document using Imaging and Ion Beam Techniques

The Grolier Codex has been a controversial document ever since its late discovery in 1965. Because of its rare iconographical content and its unknown origin, specialists are not keen to assure its authenticity that would set it amongst the other three known Maya codes in the world (Dresden, Paris Codex and Madrid Codex). The document that has been kept in the Museo Nacional de Antropologia in Mexico City, after its exposure in 1971 at the Grolier Club of New York, has been analyzed by a set of non-destructive techniques in order to characterize its materials including paper fibers, preparation layer and color compositions. The methodology included UV imaging, IR reflectography and optic microscopy examinations as well as Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS) using an external beam setup for elemental analysis. All the measurements were carried out at 3MV Pelletron Accelerator of the Instituto de Fisica, UNAM. The aim of this work is to verify if the materials in the Grolier Codex match those found in other pre-Hispanic documents. From the elemental composition we concluded that the preparation layer shows the presence of gypsum (CaSO4), color red is due to red hematite (Fe2O3) and black is a carbon-based ink. These results agree with previous analyses carried out by Scanning Electron Microscopy (SEM-EDX) on few samples. However, the presence of Maya Blue in the blue pigment cannot be assured. The examination using UV and IR lights shows homogeneity in the inks and red color but dark areas that contain higher amounts of K in the preparation layer. This paper discusses the results obtained for the UV-IR examinations and the elemental analysis. A comparison with other studies on pre-Hispanic and early colonial codex is presented.

DAVID A. SIQUEIROS: HIS MODIFICATION OF OIL- AND CELLULOSE NITRATE-BASED PAINT AND HIS ADVOCACY FOR INNOVATION, 1931–1949

Abstract Although the use of cellulose nitrate paint by David A. Siqueiros (1896–1974) is well documented, when and how he used it is not well established. This article focuses on a technical examination of six paintings Siqueiros made between 1931 and 1949. The paintings analyzed come from two collections: Museo Nacional de Arte in Mexico City and The Museum of Modern Art in New York. Findings presented here show that Siqueiros did not use cellulose nitrate for a painting he made in 1933, despite having made that claim decades later. Rather, evidence indicates Siqueiros used it in Mexico City just prior to his trip to New York in 1935 where he established a workshop to further explore innovation in painting technique and focus especially on ways to paint without a brush. Examination of a small work from 1936 or 1937 by Jackson Pollock (1912–1956), who attended the workshop, confirms he also experimented with the medium. Afterwards, in 1939, Siqueiros again altered his technique and materials in a way to suggest that rendering specific details in his paintings was more important than being restricted to the innovative “brush-free” effects developed in the workshop.