Process for acylation of a solid material (3, 9) bearing hydroxyls (-OH), referred to as reactogenic hydroxyls, which are accessible and capable of reacting with a fatty acid chloride in the gaseous state, in which: - at least one fatty acid chloride is distributed at least on the surface of said solid material (3, 9) using a distributor device having an application surface suitable for depositing said at least one fatty acid chloride at least on the surface of said solid material (3, 9) from said application surface; - said at least one fatty acid chloride distributed at least on the surface of said solid material (3, 9) is heated, at a temperature, referred to as acylation temperature, below the vaporization temperature of said at least one fatty acid chloride, so as to enable an acylation of said solid material (3, 9) by reaction of at least one fatty acid chloride in the gaseous state over at least one of said reactogenic hydroxyls of said solid material (3, 9), and; - a stream of a gaseous composition is directed over said solid material (3, 9) at said acylation temperature, so as to entrain at least one portion of gaseous hydrochloric acid formed by the acylation reaction; characterized in that the application surface of the distributor device is a velvet provided with velvet filiform elements that are non-reactive with respect to said at least one fatty acid chloride and are suitable for: ∘ taking up said at least one fatty acid chloride by contact with said at least one fatty acid chloride, and; ∘ releasing said at least one fatty acid chloride by bringing the filiform elements of the velvet into contact with said solid material (3, 9); the distribution step (12, 14) being carried out so as to distribute over said solid material (3, 9) an amount of said at least one fatty acid chloride of between 20 mg/m 2 and 1 g/m 2 surface area of said solid material (3, 9). - at least one fatty acid chloride is distributed at least on the surface of said solid material (3, 9) using a distributor device having an application surface suitable for depositing said at least one fatty acid chloride at least on the surface of said solid material (3, 9) from said application surface; - said at least one fatty acid chloride distributed at least on the surface of said solid material (3, 9) is heated, at a temperature, referred to as acylation temperature, below the vaporization temperature of said at least one fatty acid chloride, so as to enable an acylation of said solid material (3, 9) by reaction of at least one fatty acid chloride in the gaseous state over at least one of said reactogenic hydroxyls of said solid material (3, 9), and; - a stream of a gaseous composition is directed over said solid material (3, 9) at said acylation temperature, so as to entrain at least one portion of gaseous hydrochloric acid formed by the acylation reaction; characterized in that the application surface of the distributor device is a velvet provided with velvet filiform elements that are non-reactive with respect to said at least one fatty acid chloride and are suitable for: ∘ taking up said at least one fatty acid chloride by contact with said at least one fatty acid chloride, and; ∘ releasing said at least one fatty acid chloride by bringing the filiform elements of the velvet into contact with said solid material (3, 9); ∘ taking up said at least one fatty acid chloride by contact with said at least one fatty acid chloride, and; ∘ releasing said at least one fatty acid chloride by bringing the filiform elements of the velvet into contact with said solid material (3, 9); the distribution step (12, 14) being carried out so as to distribute over said solid material (3, 9) an amount of said at least one fatty acid chloride of between 20 mg/m 2 and 1 g/m 2 surface area of said solid material (3, 9).