Publication Type:Journal Article
Source:Studies in Conservation, Volume 53, Number 2, p.81-92 (2008)
A thirteenth-century sacred and profane wall painting has been rediscovered during renovation work in a city castle in Krems, Lower Austria. A frieze with alternating blue circles and green diamonds attracted attention to the unusual green colour. Several analyses by means of light microscopy, scanning electron microscopy–energy-dispersive X-ray analysis and laboratory and synchrotron X-ray diffraction show that the green colour stems mainly from clinoatacamite, a copper trihydroxychloride polymorph of Cu2(OH)3Cl which has probably been synthesized for this masterpiece. The pigment has been mixed in a lime matrix.