Water-repellent properties of fluoroelastomers on a very porous stone: Effect of the application procedure

摘要

A fluorinated elastomeric material with enhanced hydrophobic properties has been studied as a protective coating on Lecce stone. The polymer has been applied, as a butyl acetate solution, on stone specimens according to two different methodologies, i.e. brushing and capillary absorption. The application performed by brush (amounts equal or greater than 50 g/m~2) induces the formation of a superficial film, which prevents condensed water from penetrating but, at the same time, considerably reduces the vapour permeability. On the contrary, when the fluoroelastomer solution is applied by the capillary absorption technique (amounts in the 25-75 g/m~2 range), reduction of vapour permeability is acceptable but a poor protection against water penetration is observed. It can be due to a deeper penetration of the polymeric material, which is more homogeneously dispersed in the stone without forming a hydrophobic coating on the surface.