Vinylester resins (VE resins) are produced by esterifying epoxy resins with unsaturated carboxylic acids, usually (meth) acrylic acid. As epoxy (EP) and polyester resins (UP), VE resins are used as a matrix in composites, where their strength and other properties are between those of epoxy and polyester resins. The viscosity of the VE resins is lower than that of EP and UP resins (VE about 200 cps, UP about 500 cps, EP about 900 cps). They are characterised by high chemical resistance, which makes them interesting for industrial applications. Because of their chemical structure, they are very resistant to hydrolysis and are therefore often used as a protective layer for polyester laminates in contact with water.