Prepare the slick backsplash by washing it thoroughly with grease-cutting detergent and water. Backsplashes may have a build-up of dust and grease, which must be removed before the surface can be prepared for painting. After you have washed the back splash, rinse it thoroughly with clean water, either with a clean, wet rag or with a spray bottle filled with clean water. Dry the backsplash with towels.
Put fresh, medium-grit -- 200-grit -- sandpaper in the electric sander. Sand the entire surface of the slick backsplash with the sander to roughen the surface. This step gives the primer and paint a textured surface to grip, which greatly improves the longevity of the paint job. Continue sanding the backsplash until the entire surface feels rough to the touch.
Use a polyester paintbrush to apply a thin but even coat of glossy surface primer. Read the can carefully to make sure the primer is intended for glossy surfaces because regular latex primer will not provide as much adhesion to slick surfaces. If, after you have finished the first coat, you can still see streaks of the original color beneath the new primer, wait two hours and apply one more coat. Rinse out your paint brush thoroughly, and allow it to dry while the primer dries.
Apply a coat of exterior semi-gloss or high-gloss paint. Exterior paint is designed to handle humidity and water, which are conditions your kitchen walls experience. Use the polyester brush again to apply the exterior paint because the polyester brush will show fewer brush marks. Let the first coat dry for two hours before applying a second coat. If you wish to add a contrasting design to the walls, now is the time to add it. Paint a design directly on to the backsplash with a contrasting color, or use stencils to add a design. Let the paint dry overnight.
Add a coat of clear polyurethane to the backsplash. Use a paint brush or a small paint roller for this step, whichever you prefer. The clear polyurethane adds a layer of protection to the paint and provides extra durability, which is especially important in the kitchen.