Spray paint can adhere to many different types of surfaces, but getting it to stick to aluminum requires a little bit of extra prep work. First, the surface must be cleaned with a degreaser or soap and water. Next, if the aluminum is bare, it needs to be sanded with fine-grit sandpaper until it's dull. Once the surface is prepped, you can apply a primer designed for use on metal surfaces. Finally, once the primer is dry, you can apply your topcoat of spray paint.