TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The acidic aqueous solution is a solution of acetic acid, formic acid, oxalic acid, nitric acid, sulfuric acid or hydrochloric acid. The acidic aqueous solution is applied to the glass-containing surface with organo silane glass fiber anchoring agent, or applied to surface of a fiber-containing composite material by spraying. The organo silane anchoring agent is organo silane having 1-3 readily hydrolyzable groups and containing at least one organic group attached directly to silicon atom, the corresponding silanes, silanols and/or polysiloxanes. The organo silane anchoring agent is (3-aminopropyl)trimethoxysilane, N-(2-aminoethyl)-3-amino-propyltrimethoxy silane, and/or 3-amino-propyltriethoxysilane. The surface of a fiber-containing composite material is a glass fiber reinforced plastic surface. The fiber-containing composite material is epoxy/glass fiber composite material. The organo silane anchoring agent is aminosilane of formula R1O-Si(OR1)2-R2. The object comprising glass fiber reinforced composite material is wind turbine blade.R1=hydrocarbon;andR2=amino-substituted 1-6C alkyl radical.Preferred Contents: The acidic aqueous solution has pH less than 3, preferably 1.8-2.2. The binding strength between laminate or interconnected objects is more than 10, preferably more than 20 MPa, as measured by single lap shear tests using universal tensile test equipment. Preferred Processes: The method further comprises subjecting surface of a fiber-containing composite material to a plasma gas treatment and/or flame treatment to etch the surface and/or to increase the amount of functional groups, e.g. hydroxyl groups on surface. The organo silane anchoring agent is used in aqueous solution, with organo silane anchoring agent at amount of 0.5%, preferably 0.1-0.15%. The coating provides functional layer on the surface of the fiber-containing composite material with a thickness of 10-30 nm. The at least two objects made of fiber reinforced composite material and further coated with adhesive are bound together on the surface of the coatings.