A ventilation insert for textiles, with at least one layer, covered at least partially by an absorption material and having ventilation openings, the openings being at least partially closeable via a liquid by swelling of the absorption material, obtainable by: a) treating a layer having ventilation openings with a mixture, containing a wetting agent, initiator, polymerizable monomer or oligomers, and a cross-linking agent, as a preliminary stage for the absorption material; and b) polymerizing the monomer or oligomer to form the absorption material while forming a bonded connection between the absorption material and the layer. The ventilation insert has a relatively low thickness, a low weight per unit area, and high flexibility permanently and independently of moisture after economical production, via one layer, self-sealingly closing ventilation openings, and containing the absorption material. The absorption material is connected to the layer by bonding, at least in some regions.