Why is aluminium foil shiny one side, dull the other

Aluminum foil is made by rolling sheets of 98.5 percent pure aluminum metal between pairs of polished, lubricated steel rollers. Successive passes through the rollers squeeze the foil thinner. Household aluminum foil is so thin (0.0005 of an inch) that the rollers can't handle it without tearing it. The final rolling is therefore done on a sandwich of two sheets, face to face. The outer surfaces emerge with a finish as smooth as the rollers, while the two face-to-face inner surfaces emerge with a matte finish. Hence, a shiny side and a duller side.