A cosmetic or dermocosmetic agent consisting of galactomannans with molecular masses in a range from 1 to 150 kDa obtained from Caesalpinia spinose and cross-linked sulfated galactans with molar masses in a range from 1 to 150 kDa obtained from Kappaphycus alvarezii. Non-therapeutic cosmetic methods in which the agent is applied on the skin in order to tens the skin and/or to form a film on the skin.