Colorimetric study of the tiles in Patio de las Doncellas of the Real Alcazar of Seville (Spain)

Colorimetric and goniocolorimetric measurements of 187 tiles in the lower gallery of Patio de las Doncellas (14^th Century) have been performed. They can be grouped around 5 main colors: white, black, blue, green and orange. Conventional color measurements proved to be insufficient for most of the samples whose goniochromatic nature requires the use of goniocolorimeters for proper characterization. The main color changes appeared from -15 degree (close to the specular direction) to +45 degree centigrade (direction perpendicular to the sample) and consisted of a lightness (L*) decrease and a chroma (C*_ab) increase. For the black samples, there was also a pronounced decrease of hue-angle (hab), as well as a high value of 16.0 for the lightness-flop index. The black and orange samples had a metallic appearance, as indicated by average metallic index values greater than 5.0. Considering a displacement between the two extreme angles of -15 degree centigrade and +110 degree centigrade, the average CIELAB color differences were considerably high, ranging from 4.1 (white group) to 31.2 (orange group). Current methods and results for the tiles in Patio de las Doncellas may be useful for future work of conservators. (Author)