Protective treatment for porous materials

The invention relates to a method for treating a surface of a porous material in an environment, said method comprising the steps of: I. Setting the temperature of said surface to a value T1 and setting the pressure of said environment to a value P1, II. contacting said surface with a fluid having a solidifying temperature at said pressure value P1 above said value T1 and having a vaporizing temperature at said pressure value P1 below 80°C, thereby solidifying said fluid in pores of said material, thereby sealing said pores, III. treating said surface, wherein said treatment is preferably an etching or a modification of said surface, IV. Setting the temperature of said surface to a value T2 and setting the pressure of said environment to a value P2 in such a way as to vaporize said fluid,