Abstract: The present invention relates to a method for producing a layer of self-adhesive composition at least partially foamed with microballoons, wherein a foamable layer of self-adhesive composition comprising expandable microballoons and disposed between (i) two liners, (ii) a liner and a carrier, or (iii) a liner and a further layer of self-adhesive composition which (a) is not foamable or (b) is foamable and typically comprises expandable microballoons, is heat-treated at a temperature suitable for foaming for a period such that after the subsequent cooling of the layer the desired degree of foaming is attained, characterized in that the two liners or the liner during the foaming remain or remains adhering substantially completely on the respective surface of the foamable layer of self-adhesive composition on which they or it are or is disposed.