What type of paint to use for popcorn ceiling?
practical, so if you roll it use a 1 to 1 1/4 inch nap roller.
Go gently and carefully.
The problem with using water-based paints is that it will soften the compound used to create the popcorn finish and make it easier to come off. It also could absorb through the material and fall off due to gravity. However, if you never touch it (e.g. by using a sprayer and not a roller), then it will harmlessly dry with the paint. Moreover, spraying it will prevent "rubbing" the paint into the popcorn. With a sprayer, it will likely stay on the surface and not absord deeply into the popcorn. Indeed, the paint "dries" just a bit while being sprayed through the air, which reduces drying time.