Why Foil Is Shiny on One Side
Aluminum foil has a shiny side and a matte side. The shiny side is produced when the aluminum is rolled during the final pass. It is difficult to produce rollers with a gap fine enough to roll a single sheet of foil. For the final pass, two sheets are rolled at the same time, doubling the thickness of the roll. When the sheets are later separated, the two inside surfaces are matte, and the two outside surfaces are shiny.