The ancient gypsum mortars of the historical facades in the city center of Valencia (Spain)

In the historical center of Valencia (Spain), the brick facades of the civil and residential buildings which were built or modified in the end of the XVIII century and the beginning of the XX century, have been protected and decorated with continuous renderings. According to the constructive tradition, the renderings had to be made with lime mortars, but the recent studies allowed to know their real nature: they are gypsum mortars.