Problems of adhesion between support and ground layers in polychrome wooden sculptures in Guatemala

Abstract

Bibliographical research and scientific analysis of samples obtained from five polychrome wooden sculptures of the colonial tradition in Guatemala were used to study the techniques and the materials used. The methodology involved qualitative analysis of the samples and microscopic examination of cross-sections. Scanning electron microscopy (SEM) was used to identify pigments and to ascertain the composition of the gilding. It was hypothesized that the deterioration of the sculptures, particularly the separation of the ground layers from the wooden support, was due to the action of secondary products of Cedrela odorata L. The loss of adhesion of the animal glue used in the preparation may be partly related to the precipitation of the protein of the gelatin due to the action of the tannins present in the wood.