Water repellent based on methyl siliconic resin, transparent impregnating impermeable non-skin barrier for horizontal supports. Ideal for the hydrophobing of stone materials with natural (natural stones: tuffs, sandstones, limestones, etc.) and lithoids (bricks, tiles, fired bricks, etc.). Transparent waterproofing liquid, not pellicular, for tiled balconies, terraces and flights of stairs, to be applied without demolishing the existing flooring. IDROSTOP gives an excellent water repellency without altering the normal vapor permeability to the substrates on which it is applied, such as: tiles, natural stones, marbles, granites, tuff.