Abstract:
In this communication we walk through the streets of Lisbon to review the degradation of the 19th century tiled façades and assess its causes. The communication opens with a synthesis of overall principles derived from the observations and proceeds to discuss the causes of the detachments from the façades, which are a degradation of the tile coverings and not of the azulejos themselves. The adherence of the glaze to the ceramic body is then shown to be a capital factor underlying azulejo decay. Within this heading crazing, spalling and blistering are successively discussed. In the conclusive notes, the glaze adherence is presented as a time dependent propriety whose chemical decay is a subject open for research.
