The wall paintings (1519-1526) on the side walls of the cloister (a Franciscan convent) at Schwaz, Tyrol, were in such poor condition after a short time, that they were completely repainted in 1687 and again in 1898. After removing repaint, only the original and underdrawing is now left. It is possible to distinguish between the original and later paintings using crosssections for pigment analysis; the appearance and technique of the original secco wall painting has been determined. Rising damp has been destructive to two of the four side-walls. An early sulfur dioxide attack is blamed for the damage, too. At Schwaz a lot of sulfur dioxide was emitted during roasting of copper and silver ores. The peak production was during the time when the side walls of the cloister were originally painted. The vaults of the cloister were decorated later (probably about 1600) and never repainted. The appearance of the paint is now like a (glue) water paint, typical of the 19th century. But from the pigments used (smalt and malachite) this could be recognized as an old wall painting and the conversion of lime into gypsum was found as reason for its atypical appearance.