If you're looking to repair cracks in plaster walls, here are five steps to help you get the job done:
1. Prepare the area: Before you begin any repairs, clear the area around the crack of any debris and dust. Use a putty knife or scraper to remove any loose plaster around the crack. This will help ensure that the repair will adhere properly.
2. Apply joint compound: Use a putty knife to apply joint compound to the crack. Start at one end of the crack and work your way down, pressing the compound into the crack as you go. Make sure to apply enough compound to fill the entire crack.
3. Smooth the compound: Once you've applied the joint compound, use a skimmer tool to smooth it out. Feather the edges of the compound so that it blends seamlessly with the surrounding plaster.
4. Sand the area: Once the joint compound has dried completely, use sandpaper to smooth the surface. Start with a coarse grit sandpaper and work your way down to a finer grit to get a smooth finish. During this step I would encourage the use of proper respiratory gear. The fine particles that are released can caused trouble breathing or eye irritation.
5. Paint or finish the area: Once the surface is smooth, you can paint over it to match the surrounding area. If you're repairing a larger area, you may need to apply texture to match the surrounding wall. If you have peeled back the layers of wallpaper only to discover never been painted plaster you will need to use an oil based primer in order for proper paint application.
By following these steps, you should be able to repair cracks in plaster walls and restore them to their former glory.