1. Prepare the Crack Prev Next Cut away loose plaster with utility knife. Turn knife to make opening wider and more clean-lined. Remove debris while preserving structural integrity of surface around it. Clean away loose plaster and dust with vacuum cleaner. Up Next Why do drywall screws pop out? How to Texture a Ceiling How far apart should you place drywall screws? How do you estimate the number of screws in drywall? Do black drywall screws rust?