I have just spent an interesting 10 minutes on a pot growers site. I now know all about Mylar, Foylon, Panda film, Orca etc etc.you were right about mirrors it seems not a good idea and the dull side of foil is better than the shiny side although foil is considered poor at best
Hammered style of films are best.
A very intesting 10 minutes..wow..and the Drs wanted me to go on it a couple of years ago, still do as a matter of fact, maybe I can claim a new the grow system on my taxes