09/25/2023
To prepare your walls for paint remove any loose, peeling paint with a paint scraper and/or sandpaper. Sand all edges to smooth the surface. Fill small cracks and nail holes with spackling compound using a putty knife. Let dry and then sand smooth. Remove any dust with a moist cloth. For larger holes and/or cracks use mesh joint tape, covering it with joint compound, Consider lightly sanding the entire surface to ensure good paint adhesion. Scrub all surfaces with a mild detergent and a sponge or cloth to remove dirt, grease, oil, etc. Rinse the surface well and allow it to dry. Apply a primer to the surface. Avoid "spot priming," which can result in a non-uniform appearance between primed and unprimed areas.
Click for more. https://www.calres.ca/why-proper-surface-preparation-is-important-for-residential-painting-projects/