Couple aux têtes pleines de nuages
Salvador Dali, 1936
During its recent conservation treatment it was noted that in some areas the upper part of the paint layers had become transparent and was covered with little droplets. These transparent areas were first interpreted as a separate, transparent layer. However the material was identified as a mixture of zinc soaps and zinc sulphides. In fact the transparent areas contained severely degraded zinc white.
Secondly, concentric rings were noted in the shoulder of the woman. These phenomena strongly disturb the appearance of the painting. Remarkable are the inhomogeneous distribution (droplets and concentric rings), the high degree of zinc white degradation, and the relative short period of time in which the degradation has taken place. The history of the painting is known. While placed behind glass in a frame, it was incidentally exposed to relative high temperatures.
More insight needs to be gained into the influence of environmental factors on zinc soap-related degradation processes for the preservation of the painting.