The invention relates to a ventilation insert (1, 1') for arranging in or on textiles, comprising at least one layer (2), which is covered at least partially by an absorption material (3) and has ventilation openings (4), which ventilation openings (4) can be at least partially closed under the influence of liquid as the result of a swelling of the absorption material (3), obtainable by a method comprising the following steps: a) treating a layer (2) having ventilation openings (4) with a mixture, containing a monomer or oligomer that can be polymerised and a cross-linking agent, as a preliminary stage for the absorption material (3), and containing a wetting agent and an initiator and b) polymerising the monomer or oligomer to form the absorption material (3) while forming a bonded connection between the absorption material (3) and the layer. With regard to the aim of designing and developing a ventilation insert in such a way that the ventilation insert has a relatively low thickness and a low weight per unit area and high flexibility permanently and independently of moisture after economical production, can be designed with one layer, closes ventilation openings in a self-sealing manner, and captively comprises the absorption material, the ventilation insert is characterised in that the absorption material (3) is connected to the layer (2) in a bonded manner at least in some regions.