Stonework that has previously been painted should be less difficult to paint than stone that has never been painted. Because stone is porous, it typically soaks up colour and requires more paint than other surfaces to complete the job. Stone that has already been painted has a foundation from which to work, and the job will require less effort. You can change the colour of your stonework or simply touch up the existing colour.
Cover any flooring underneath the stone with a tarp. Remove any pictures, mirrors or other wall hangings from the stonework. Remove nearby furniture and rugs.
Mix trisodium phosphate and water in a bucket according to the package instructions. Submerge a sponge into the mixture and scrub the stone to remove all residues. Rinse with clean water. Allow the stone to dry completely.
Sand any peeling or chipping paint with medium-grit sandpaper. Sanding will create a smooth surface foundation for the new coat of paint. Remove all rough or peeling paint with the sandpaper. Wipe away all sanding debris with a tack cloth. If your original painted stonework is in good shape, skip this step.
Apply masonry primer between the cracks in the stone, using a paintbrush.
Paint the face of each stone with the primer. Allow it to dry completely.
Apply latex paint between the cracks in the stone with a paintbrush. Masonry paint will adhere well to the stones. For exterior applications, choose a paint formula for outdoor use.
Paint the face of each stone with the latex paint. Allow the first coat of paint to dry to the touch. Apply a second coat of paint using the same techniques, and allow it to dry completely.
Exterior stonework is painted using the same techniques used to paint interior stone. Choose a paint formulated for outdoor use.