Materiales de Construcción, Vol 50, No 258 (2000)

Cleaning of stone materials in the Cathedral de Valladolid (Spain)

R. Fort
Instituto de Geología Económica (CSIC-UCMF), Spain

M. C. López de Azcona
Instituto de Geología Económica (CSIC-UCMF), Spain

F. Mingarro
Instituto de Geología Económica (CSIC-UCMF), Spain


Two types of black crusts showing gypsiferous and calcareous compositions are recognized on the front-walls of the Valladolid Cathedral. On the basis of several petrophysical parameters, in particular compacity, sorption and desorption kinematics of carbonate rocks used building the cathedral, we conclude that the most appropriate cleaning method of the ashlars is washing with water. Highest efficiency of the method is attained with water at 90ºC and at a pressure of 120 bars. This assessment is valid for most of the carbonate rocks of the cathedral except for detrital pelmicrites because of their low compacity which makes that water pressure for cleaning must not exceed 50 bars. The processing of cleaning with water should be preceded by alkaline treatment (NaOH and EDTA) of the rock surface.


cleaning methods; limestones petrophysics; chromatic parameters; monuments conservation; architectural heritage

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