Abstract: This invention relates to a process for coating mineral, organic or metallic substrates, said substrates being either microscopic, such as pigment, filler, cement or metal particles, or macroscopic, such as large sized materials.The process according to the invention comprises a first step consisting in coating said substrate with a first layer of a composition comprising a liquid medium containing a polyhydroxylated polymer and a transition metal selected among the metals of the IB, IIB, IIIB, IVB, VB, VIB, VIIB and VIIIB groups of the periodic arrangement of the elements, capable of forming a polymer/metal complex, preferably a complex of polyvinyl alcohol and copper II, a second step consisting in applying on the first layer a polymerizable material capable of being grafted on the first layer and a third step consisting in causing said polymerizable material to become grafted to the first layer by polymerization thereon. The polymerizable material contains preferably acrylic or methacrylic unsaturations.