Please help to keep this site free. If you like the info provided here for you, please click the link below and donate any amount you like. Thank you for helping!
Plaster wall treatment is used in older style homes and high end expensive homes being built today. This process is constructed in three layers. First a base coat, second a thick coat for strength and a skim coat for a finished look. It may be applied over wood lath, metal mesh, special gypsum wallboard or masonry and a variety of textured or slick finishes can be applied.
First the crack must be grooved out to about 1/8-inch with a screwdriver or a mud knife. Clean out the loose debris and wipe with a damp cloth. Next using a drywall mud knife, apply the fresh mix into the groove moving the knife in all directions removing all the excess from the wall as this will reduce your sanding time. After the material has dried completely it is ready for sanding. Sand using a wood block wrapped with fine grade sandpaper, sanding in a circular motion. Once finished it is now ready for priming and painting.
Patching larger crack is basically the same process except that you can only fill the crack about halfway, let it dry and then you must score or scratch the new surface so that the next coat will have better bonding. Fill with a finishing mix and scrape with a straight edge to remove excess plaster. You will need to experiment with different ways to achieve a good match for existing textures.