Don safety equipment. Early popcorn mixtures contained asbestos, so it’s advisable to protect yourself from the possibility of coming into contact with the carcinogen by donning rubber gloves, a mask and safety goggles.
Cover your floor and any furniture underneath the damaged popcorn with a tarp. This will protect them from falling popcorn and any spray that doesn’t end up on your ceiling.
Remove popcorn from the damaged section of the ceiling. Popcorn comes off easily by simply spraying warm water on the damaged portion, then scraping it off with either a putty knife or scraping trowel.
If the popcorn has been painted over, water will not soften it, so you will need to use a chemical paint stripper.
Apply a primer, such as Kilz or BIN. They will cover any stains on the ceiling and are usually available in quick-drying and spray-on formulas.
Spray a thin layer of the ceiling popcorn over the damaged area, then go back and spray it again. Repeat the layers until the area matches the surrounding popcorn.