To paint a popcorn ceiling, protect the work area from paint with a plastic sheeting, and apply at least two coats of paint to the ceiling using a paint roller or an airless spraying tool. Allow the paint to dry between the coats.
Start by gathering necessary tools and material, including paint, a tray, a segmented paint roller, a plastic sheeting and a dust mask. Replace the paint roller with an airless spraying device if you prefer to spray paint the ceiling. Cover the walls, floor and other items in the room with the plastic sheeting, and secure the sheeting in place with a masking tape. Wearing the dust mask, fill the tray basin with paint, soak in the segmented paint roller, and clear the roller of excess paint using the paint tray's textured surface to ensure even painting. Paint the ceiling, moving the roller in one direction. Allow the paint to dry, and paint again.
As for spray painting, protect the work area just as in hand painting, fill the holding compartment of the spray device with paint, taking care to slightly dilute the paint with 10 to 20 percent water in case the paint is thick. Spray the whole ceiling in one direction, and allow the coat to dry. Add another coat, this time painting in the opposite direction to the initial coat. For a porous ceiling, repeat the process as needed until you achieve an even texture.