I tried to paint the chipped paint on my aluminum door. Of course, I sanded off the old paint. I think it's good for small spots. However, don't expect it to have the same texture and shade as the old paint on your door. So it will look like a small patch. If there are many chips in the paint of your aluminum, it's better to sand it all down and repaint it from scratch. I did it as a temporary solution until summer comes to take the door off and spray paint it