Reconversion of altered lead pigments in alpine mural paintings

Techniques of mural painting in middle and northern Europe differ from those of the classic type of Italian fresco. After a brief comparison of documentary evidence with actual alterations in colours on thirteenth- to eighteenth-century murals, the first complete reconversion of darkened lead white on northern secco painting is described. The vault at Castle Strechau in Styria was painted in fine secco colours over a priming layer of lead white and chalk in about 1580. The lead pigments have altered progressively over the last 120 years. The reasons for the chemical reactions are discussed and the results of reconversion using the Florentine method are reviewed.