UCLA/Getty Conservation Program

A graduate conservation training program focusing on the conservation of archaeological and ethnographic materials


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The Significance of Surface in Central African Masks: Pigment Identification of Polychrome Wood Masks from the Congo

This past Saturday, three of our 1st year students, Brittany Dolph, Geneva Griswold, and Casey Mallinckrodt, presented a poster at the Southern California Society for Microscopy and Microanalysis (SCSMM) meeting on a project they and their classmates conducted to identify pigments on a group of Kuba masks from the Fowler Museum at UCLA. The project was undertaken as part of a course on microscopy and microanalysis offered in the conservation program. The analysis of the pigments and binders used on the masks was done not only by students in the UCLA/Getty Program but was truly a collaborative effort involving students from UCLA’s Dept. of Material Science and Engineering, UCLA’s Archaeology Graduate Interdepartmental Program, UCLA’s Dept. of Bioengineering, and the Dept. of Anthropology, CSU, Fullerton who all took the class and lent their different expertise to the project.

Geneva Griswold and Brittany Dolph discuss their poster with attendees of the SCSMM meeting.

Abstract
The treatment of surfaces in African masking traditions reflects the adaptation of materials for cultural ritual and use. This poster presents a study of polychrome surfaces using microscopic and microanalytical techniques, whose results provoke questions regarding the masks’ methods of manufacture, material adaptation, dating and provenance. The coloring materials of different chemical composition and microstructure were sampled from a group of eight polychrome wood masks from the Kuba region of the Democratic Republic of Congo and now in the collection of the Fowler Museum at UCLA. Following a thorough non-invasive investigation employing forensic imaging, X-ray fluorescence (XRF) spectroscopy and ultraviolet, visible, near infrared (UV/Vis/NIR) spectroscopy, dispersion and cross-section samples of the wood and paint layers were analyzed using polarized light microscopy (PLM), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) in order to ascertain their chemistry and composition. The results indicated that while all eight masks analyzed shared common iconographic and stylistic characteristics, six masks exhibit similar materials with only two of the masks being outliers.

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Project News: Research and treatment of flaking arsenic containing paint layers on a Ptolemaic mummy cartonnage

The work described in this poster was conducted as part of a Master’s thesis project for the UCLA/Getty Conservation Program and presented at the Annual Conference of the Association of North American Graduate Programs in Conservation (ANAGPIC), Buffalo State College, April 24-25, 2009.

A Ptolemaic mummy cartonnage, belonging to the Robert V. Fullerton Museum at California State University, San Bernardino, seemed to be suffering from an alteration of the paint layers found on the object. The pigments used to decorate the mask had darkened and several areas, primarily those a dull yellow in color, displayed severe flaking. The flaking yellow pigment was found on alternating squares of the checkerboard pattern on the head, on the double headed cobra on the back, on the areas of the wig, above and below the headband, and on the face of the standing figure on the PL side of the mask. The aims of this project were to identify the cause of the flaking and treat the cartonnage.

In order to determine the causes of alteration to the dull yellow pigment, a technical study was conducted to identify the materials used in the manufacture of the mask, focusing on the pigments and binders applied to the areas now flaking. X-ray fluorescence (XRF), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), polarized light microscopy (PLM), gas chromatography-mass spectroscopy (GC-MS) and ultraviolet (UV)-fluorescence were employed to characterize the cartonnage. The ground was found to be made primarily of calcite (CaCO3) and the binder used for the pigments was a gum. Fatty acids identified in a brown material covering areas of the surface were thought to possibly be from the embalming material used for the mummy. The flaking paint was composed of the arsenic-containing pigment orpiment (As2S3), in addition to possible altered forms of the pigment such as arsenolite (As2O3) and pararealgar (AsS). Comparison of the flaking yellow squares on the head to the non-flaking yellow squares showed they both contained arsenic, but the quantity of arsenic in the flaking squares was higher.

Though the preliminary results of this research have helped to identify the materials used in the decoration of the cartonnage, no clear answer has been found to explain why some areas painted with arsenic-containing pigments are flaking while others are not. Further analysis will be undertaken to try and determine the cause of the flaking and whether the differences in the amount of arsenic in the yellow paint may be influencing the condition of the pigment in those areas. Treatment will also be conducted on the cartonnage to reduce the glossy material found on the surface, identified as Paraloid B-72 (an acrylic co-polymer resin), and to consolidate the areas of flaking paint.

Egyptian cartonnage images courtesy of Robert V. Fullerton Art Museum, gift of the Harer Family Trust, 2001

Egyptian cartonnage images courtesy of Robert V. Fullerton Art Museum, gift of the Harer Family Trust, 2001