A method for preparing the surface of a glass substrate so that resist maial may be directly applied to the surface and adhere thereto. The invention is particularly useful in the fabrication of relief masks used for pattern generation in planar thin film overlays, which masks are used to provide intimate contact between a photoresist surface and a masking pattern during exposure of the photoresist surface. The present method comprises cleaning of the glass substrate, boiling the substrate in trichloroethylene, and heating the substrate to between 160.degree. and 200.degree.C. Resist material may then be applied directly to the glass substrate.