Coated Fibrous Substrates The present invention provides a method of improving the adhesion of coatings to fibrous base materials. The method comprises treating a fibrous base material with one or more salt(s) of receptor species to provide a pre-coated fibrous base material comprising specific inorganic receptor sites within the fibrous base material. The one or more salt(s) of receptor species is selected from the groups comprising: (a) aluminium salts; (b) titanium salts; (c) zirconium salts; (d) iron salts; (e) soluble alkali silicates; or a combination thereof. The method further comprises coating the treated fibrous base material with a coating formulation comprising one or more compound(s) containing epoxy and alkoxysilane groups. The coating formulation acts as an adhesion promoter and cross-linker.