Effect of the impregnation treatment with Paraloid B-72 on the properties of old Portuguese ceramic tiles

Abstract

In this work, the effect of the impregnation with Paraloid B-72, using the protocol commonly followed in museum restoration departments, on the mechanical and water absorption properties of Portuguese tiles from XVI to XXth centuries, was studied. Mineralogical characterization of the biscuit was made from X-ray diffraction patterns. Microstructural features (pore size) were determined using scanning electron microscope (SEM) photographs. Mechanical strength was determined with four-point bending tests. The absorption coefficient and the total amount of water retained were obtained from water absorption essays, which also allowed the estimation of the open porosity. The impregnation treatment, in general, increases the mechanical resistance, reduces the porosity and modifies the water absorption behaviour of the tiles.