foil aluminum paper

[tucho58]

foil aluminum paper has a shiny side and a non shiny one  How are they used when heating food in the oven?

[Clanad]

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.
Of course, in reality, which side of the foil faces where makes little difference. It does
make for lively conversation, though...