Aluminum Foil

[Seamazter]

http://en.wikipedia.org/wiki/Aluminium_foil

While many believe that the different properties keep heat out when wrapped with the matte finish facing out, and keep heat in with the matte finish facing inwards, the actual difference is imperceptible without instrumentation.

Originally Posted by zoaElite

So the better question to ask is;
Why does tinfoil really have 2 different colored sides?

Its just part of the proccess used to create the foil.

"The shiny side is produced when the aluminium is rolled during the final pass"