In a method for preparing a mosaic luminescent screen, islands of dry precoating material are adhered to a glass support surface at the sites of the mosaic parts of the screen. Then, the mosaic parts of the screen are deposited on the islands by the slurry-direct photographic method, including development with a turbulent aqueous developing medium. The use of islands provides the necessary adherence during development of the mosaic parts with a substantial reduction in the amount of precoating that must later be removed.