PVC pipe that is exposed to sunlight should be painted to prevent sunlight from destroying the plastic. But what if you need to repair the PVC pipe later? You can’t glue pipe that has paint on it. In fact, you need to remove all of that paint from the area to be glued, even a small amount may cause leaks in the glued joint.
Using a small brush “paint” acetone onto the area of pipe where you want to remove the paint. (PVC primer will also work as a replacement for acetone, but the purple color makes it hard to make sure all the paint is off.) Allow the acetone to soak in for a few seconds then scrape off the paint with a knife blade or other metal edged tool like a putty knife. If some of the paint doesn’t easily come off re-coat the paint with more acetone. Once most of the paint is off, apply another coat of acetone. This time use a paper towel to wipe off the remaining paint. You may need to wipe down the PVC pipe 2-3 times with fresh paper towels to get a nice clean white surface. Now you can glue your joint using the normal method for gluing PVC pipe as described on the cement/glue can. The acetone will leave the pipe surface feeling sticky, that’s OK, you don’t need to wait for it to dry before you glue the joint. The primary ingredient in the purple PVC primer that is used to clean and prepare PVC pipe for gluing is acetone.