Abstract: Hydrogel foamsa) based on gelatin and water,b) optionally containing polyvinyl alcohol,c) containing a crosslinking agent selected from the group comprisingca) the compounds of at least trivalent metals or semimetals, for example boric acid, borates, aluminium salts, titanates and alkyl titanates, and/or from the group comprisingcb) organic and/or inorganic acids and/or salts thereof, for example gallic acid, gallates, phosphoric acids, phosphates, dihydroxybenzoic acid and dihydroxybenzoates,d) and optionally containing organic plasticizers, and/or auxiliary agents and/or additives.