Correct use of the contact angle in the evaluation of the protective action induced from polymer coating on the stone

The control of the protective efficacy obtained on the stone by treatments with polymers is commonly performed though the measure of the static contact angle. The measurement of the true equilibrium angle obtained through a new technique called VEICA, and the measure of the receding contact angle give more coherent parameters which better correlate with the data of absorption of awter by capillarity. The equilibrium contact angle corresponds to an average description of the surface, the receding angle corresponds, by excess, to the condition of maximum penetration of the liquid by capillarity.