Colorimetric Evaluation of Pictorial Coatings in Conservation of Plasterworks from the Islamic Tradition

A colorimetric evaluation of protective treatments for traditional Islamic plasterworks revealed that consolidants, including barium hydroxide, acrylic copolymer, polyvinyl butyral, ethyl silicate, and bacterial carbonatogenesis, induced average color differences of 10.7 and 6.7 CIELAB units when compared to untreated specimens aged indoors and outdoors, respectively. These differences were consistent across two binders (animal glue and gum arabic) but varied among pigments, with blue and red pigments showing the highest changes. No statistically significant differences were found among the five consolidants or the two binders when outdoor-aged samples without consolidants served as a reference. Polyvinyl butyral emerged as the most effective consolidant for the tested paints, followed by ethyl silicate. The study analyzed 56 test specimens prepared to mimic original pictorial plaster remains from the Courtyard of the Maidens in the Real Alcázar, Seville and subjected them to natural ageing for one year.

Collado-Montero, F. J., Calero-Castillo, A. I., Melgosa, M., & Medina, V. J. (2018). Colorimetric Evaluation of Pictorial Coatings in Conservation of Plasterworks from the Islamic Tradition. Studies in Conservation, 64(2), 90–100. https://doi.org/10.1080/00393630.2018.1460924