US Patent 10378153 Method for hydrophobing a cellulose substrate

Method for hydrophobing a cellulose substrate (1), which comprising a first side and a second side, which faces away from the first side. The method comprising the steps of drying a cellulose substrate (1) to a dry content above 80%, preferably above 85%, adding a vaporized fatty acid halide, to the first side of the cellulose substrate, and, at the same time perform vacuum sucking at the second side of the cellulose substrate, such that, the vaporized fatty acid penetrates the cellulose substrate (1) in a predetermined direction through the substrate.