Almost three hundred Spanish colonial missions—or their remains—are scattered over the vast state of Chihuahua in northern Mexico. A few of them still display painted decorations on the wood ceilings and walls. The decorated areas vary greatly, from the whole ceiling of the main aisle to just a few square meters in a lateral chapel, and so does the conservation state of the paintings. In this context, the information regarding the paintings’ composition plays a key role in the restoration and conservation processes. For the gathering of such information, we propose a combined methodology for a fast, non-destructive and non-invasive characterization of such paintings with a minimum of techniques. This methodology includes false color infrared imaging as a first approach to determine the composition of large areas of the paintings and the homogeneity of the materials used in the painted areas, followed by small area analysis by X-ray fluorescence and fiber-optics reflectance spectroscopy. This methodology was applied to characterize the elemental and molecular composition of the decorations for four missions in Chihuahua in a fast and specific manner, revealing the use of a mix of mineral and organic materials including indigo and cochineal, and detecting differences between the missions. The methodology presented here can be easily applied for the study of a wider number of missions in Chihuahua and other regions to provide outstanding information of materials, pictorial techniques and deterioration conditions.

This article presents the early ATR-FTIR and FORS results of the analysis carried out in five polychrome wooden ceilings from different Jesuit Spanish colonial mission churches. These mission churches date between 1674 and 1723 and are located in the rural villages of Santa Maria, Cusihuiriachi, Coyachi, La Joya, and Rosario in the Northern Mexican State of Chihuahua. The decorative motifs in all five church sites were executed using a similar color palette and painting technique although the pictorial quality differs from one site to the next. The samples collected from the interior of the La Asunci on de Santa Mar ıa de Cuevas are of considerable importance as this site is one of the most significant models of colonial architecture, containing some of the oldest examples of colonial figurative art in Northern Mexico. The scope of this research is to identify and compare the pigments and techniques used in the decorative surfaces of these five selected mission churches. Preliminary FTIR results have unexpectedly determined the presence of indigo and cochineal (not traditionally used among Chihuahua natives) and possibly a mixture of both to produce different tones to decorate the wooden ceilings and choirs of the five missions studied.

An interdisciplinary and multi-institutional group of science and art conservation specialists has provided new insight into the painting materials used in the polychrome walls and wooden ceilings in four seventeenth century Spanish colonial churches of Nueva Vizcaya (Chihuahua, Mexico). A multi-analytical study of the decorative surfaces was performed in situ using spectroscopic approaches (XRF, FORS), False Colour Infrared Reflectography-IRFC, as well as micro sampling for ATR-FTIR, LM and GC/MS laboratory analyses. A survey of natural resources were also studied by ATR-FTIR and LM to elucidate the natural occurrence of a select number of materials found in the surrounding areas of the churches. The present paper presents a multi-analytical study and characterization of green, red-orange and black colour pigments and binders selected from the decorative surfaces. The aim of this study is to highlight relationships between local materials and those from the original polychrome ceilings, in order to understand the material and technological influences that converged in the Spanish colonial architecture of northern Mexico.