Which side up when using Aluminium cooking foil?

The shiny side is slightly better reflector of heat. Face that side of the foil in the

appropriate direction. To keep things cold, put the shiny side on the outside -- that

will reflect incoming heat. To keep things warm, face the shiny side inward toward the

hot food -- to reflect the heat that is trying to escape back into the food.

Note that people often bake potatoes with the shiny side out -- that is because it makes

for a better (prettier) presentation. In reality, baking them that way reflects the

incoming heat on the outside, slightly slowing the cooking process.

Aluminium Foil

If you put the shiny side on the inside [facing the food] whilst cooking in the oven/in a pan, it keeps the heat inside better and thus cooks more evenly/quicker. =)

Use the dull side when cooking, think its more non-stick