<p>A process for increasing the hydrophobicity of a porous product by treating the product or a composition providing the product, with a water repellent material, characterised in that the porous product or a composition providing the product is treated with an aqueous suspension of microcapsules, where the microcapsules comprise a water repellent organopolysiloxane core material and a shell of a silicon-based network polymer comprising silica units.</p>
