Systematic alteration survey and stone provenance for restoring heritage buildings: Punta Begona Galleries (Basque-Country, Spain)

摘要

Punta Begona Galleries (Getxo, Spain) are a fine example of early twentieth century architectural heritage. Built during the early years of reinforced concrete usage, they were decorated inside with ornamental stones to project an image of exclusivity and luxury. After years of neglect, it is essential to characterise construction materials, including the determination of their origin, current state of conservation and restoration options, before undertaking a recovery project respectful with the original edifice. With this aim, a detailed study was made of the current state of conservation of the lithologies that decorate the salon of the building using an alphanumerical matrix of alterations to define the type of existing disturbances and assess their intensity. Complementarily, a petrological, isotopic and mineralogical study of these materials was made in order to determine their provenance. They include Carrara marbles and a local limestone (Red Ereno) which was internationally renowned, in particular being used in buildings such as St. Peter's Basilica in the Vatican. In this paper a first complete description of this stone has been made. By combining the two sources of information, guidance on the most appropriate restoration options in each case is given. The option of polishing materials includes a specific study of the degree of wear. By means of which it is verified that small wear ( 350 mu m) is sufficient to produce high gloss values (100GU).