Subject: What happens to the heat reflective value of aluminium when it is painted?

I have a home made air tight cooler built of plastic lumber, solid thermo 
insulation and covered on the outside with sheet aluminium.  The aluminium 
oxidizes and doesn't clean easily.  For these reasons, I would like to paint 
it.  It is very important that the cooler not lose more than a small percentage 
of its ability to reflect heat because of painting.  Does the aluminium reflect 
the heat back through a white paint just as it does into air?

Re: What happens to the heat reflective value of aluminium when it is painted?