When and if you paint anything aluminum and want it to stick, use something like this.
Clear coat is unnessasary and the more material you put on the chances of it chipping will be higher, just use a quality spray enamel and follow instructions. Use a red scotchbrite pad and throughly rough up alminum prior to prime and paint.
http://www.westmarine.com/1/1/27913-...ay-primer.html