This invention provides a method of increasing adhesion of radiation-cured, inner primary coatings on glass optical fibers. A glass optical fiber drawing tower has a controllable variable amperage electron beam for exposing different sections of a glass optical fiber with different amperage levels of electron beam radiation. The different sections of the glass optical fiber after being exposed to the selected amperage levels of electron beam radiation are then coated with an inner primary coating composition which is finally cured by exposure to actinic radiation. Later formed sections of the same glass optical fiber can be exposed to different amperage levels of electron beam radiation and then coated and cured. The different sections of the glass optical fiber which have been coated with an inner primary coating using this method demonstrate correspondingly different degrees of coating adhesion. Reduced levels of adhesion promoter are required for inner primary coating compositions when using this method.