Thanks everybody for sharing all that you know. Thanks to Sandy for bringing the practical answer into the thread. This is good news that plain white paint is as good as anything else. I really did not want to get into attempting to line the box with mirror like material.
As an aside.....
I caught Sandy's answer to a question on ABC Pyro on Tuan's site. I just want to say that we are indeed blessed not only to have Sandy's wealth of knowledge shared here, but the crown jewel is that he has the wisdom and maturity to temper his responses with a great deal of practical common sense.
A personal trait I fear that is often sorely lacking from some of the answers I have seen throughout the years. (of course nobody here comes to mind) I cannot sing my praises loud enough in respect for Sandy and how an answer like that has moved him very high on the ladder in regards to being listened to and believed when he offers a candiate opinion.