Fibrous material, e.g. cotton, silk, viscose rayon and nylon, is coated with a phenolicaldehyde resin-containing rubber latex other than a butadiene-styrene-vinyl pyridine latex and then with a brominated butyl rubber cement containing sufficient bromine to improve the adhesion of the fibrous material to natural and synthetic rubber. The phenolic-aldehyde resin-containing rubber latex, which may be a natural rubber, butyl rubber or polyhaloalkadiene rubber latex, is preferably adjusted to a pH of 7-13 and aged at 40-150 DEG F. for 20 minutes to 30 hours before application, and the latex-coated fibrous material may be dried, preferably with stretching, for 0.05 to 30 minutes at 200 DEG to 550 DEG F., whereby the resin is partially set and the volatile materials driven off. The dried, coated fibrous materials are then treated with the brominated butyl rubber cement which preferably contains at least 0.5% by weight of combined bromine but not more than 3 combined atoms of bromine per double bond in the polymer and preferably contains fillers such as silica, clays, alumina, diatomaceous earth, calcium carbonate, silicaalumina and carbon black, with or without curatives such as sulphur, zinc oxide, derivatives of thiuram or carbamic acid, quinoid compounds, primary or polyfunctional amines, phenol-dialcohol resins of the polymethylolphenol type, benzothiazyl disulphide, mercaptobenzothiazole, mercapto imidazoline and sulphonamides. The brominated butyl rubber may be dissolved in a C5 to C10 hydrocarbon or halogenated hydrocarbon such as ethylene dichloride, chloroform or carbon tetrachloride, and after application of the solution the fibrous material may be dried at 150-300 DEG F. for 0.5-30 minutes. The material may then be imbedded as by calendering in an unvulcanized rubber matrix such as natural rubber, butyl rubber, chlorinated or brominated butyl rubber, neoprene rubber, GR-S rubber, "Buna-N" rubber ("Buna" is a Registered Trade Mark), vinyl pyridine-butadiene copolymers and tripolymers of butadiene-acrylonitrile-vinyl pyridine and vulcanized in situ for 0.5 to 90 minutes at 200 DEG to 450 DEG F. Butyl rubber comprises a copolymer containing 85 to 99.5% of a C4 to C8 iso-olefin, e.g. isobutylene, the remainder being a C4 to C10 multiolefin, preferably a C4 to C10 conjugated diolefin such as butadiene, dimethyl butadiene, piperylene or isoprene, and the butyl rubber latex may be prepared by dissolving butyl rubber in a hydrocarbon solution which is then emulsified with water using non-ionic, anionic or cationic emulsifiers and the hydrocarbon solvent removed by stripping; alternatively, the latex may be prepared in intensive mixing equipment, e.g. colloidal mills or sanic mixers, a protective colloid, e.g. polyvinyl alcohol, being added. Methods of brominating butyl rubber are described, and a number of reagents for this purpose are specified. The treated fibrous material may be used in constructing tyre carcasses, conveyer belts, transmission belting, rubber hosing, e.g. steam hose, air springs and other products built up of a plurality of laminations of cord and rubber. Specifications 243,016 and 565,974 are referred to.ALSO:Fibrous material, e.g. cotton, silk, viscose rayon and nylon, is coated with a phenolicaldehyde resin-containing rubber latex other than a butadiene styrene-vinyl pyridine latex and then with a brominated butyl rubber cement containing sufficient bromine to improve the adhesion of the fibrous material to natural and synthetic rubber. The phenolic-aldehyde resin-containing rubber latex, which may be a natural rubber, butyl rubber or polyhaloalkadiene rubber latex, is preferably adjusted to a pH of 7-13 and aged at 40 DEG -150 DEG F. for 20 minutes to 30 hours before application, and the latex-coated fibrous material may be dried, preferably with stretching, for 0,05 to 30 minutes at 200 DEG to 550 DEG F., whereby the resin is partially set and the volatile materials driven off. The dried, coated fibrous materials are then treated with the brominated butyl rubber cement which preferably contains at least 0,5% by weight of combined bromine but not more than 3 combined atoms of bromine per double bond in the polymer and preferably contains fillers such as silica, clays, alumina, diatomaceous earth, calcium carbonate, silica-alumina and carbon black, with or without curatives such as sulphur, zinc oxide, derivatives of thiuram or carbamic acid, quinoid compounds, primary or poly-functional amines, phenoldialcohol resins of the polymethylol-phenol type, benzothiazyl disulphide, mercaptobenzothiazole, mercapto imidazoline and sulphonamides. The brominated butyl rubber may be dissolved in a C5 to C10 hydrocarbon or halogenated hydrocarbon such as ethylene dichloride, chloroform or carbon tetrachloride, and after application of the solution the fibrous material may be dried at 150 DEG -300 DEG F. for 0,5 to 30 minutes. The material may then be embedded as by calendering in an unvulcanized rubber matrix such as natural rubber, butyl rubber, chlorinate or brominated butyl rubber, neoprene rubber, GR-S rubber, Buna-N rubber ("Buna" is a Registered Trade Mark), vinyl pyridine-butadiene copolymers and tripolymers of butadieneacrylonitrile-vinyl pyridine and vulcanized in situ for 0,5 to 90 minutes at 200 DEG to 450 DEG F. Butyl rubber comprises a copolymer containing 85 to 99,5% of a C4 to C8 isoolefin, e.g. isobutylene, the remainder being a C4 to C10 multiolefin, preferably a C4 to C10 conjugated diolefin such as butadiene, dimethyl butadiene, piperylene or isoprene, and the butyl rubber latex may be prepared by dissolving butyl rubber in a hydrocarbon solution which is then emulsified with water using non-ionic, anionic or cationic emulsifiers and the hydrocarbon solvent removed by stripping; alternatively, the latex may be prepared in intensive mixing equipment, e.g. colloidal mills or sonic mixers, a protective colloid, e.g. polyvinyl alcohol, being added. Methods of brominating butyl rubber are described, and a number of reagents for this purpose are specified. The treated fibrous material may be used in constructing tire carcasses, conveyer belts, transmission belting, rubber hosing, e.g. steam hose, air springs and other products built up of a plurality laminations of cord and rubber. Specifications 243,016 and 565,974 are referred to.