What are the three layers of aluminum foil?

Answer 1

Pure aluminium foil (not mylar), has three layers, a protective oxide coating on each face of the foil, and pure metal inbetween.

Mylar is a metallised plastic, one variety has a polyethlene terephthalate film coated on both sides with a thin layer of aluminium. From a microscopic view the aluminium layer has a protective layer of oxide.

Answer 2

Aluminum foil typically consists of three layers: the shiny aluminum layer on the outside, a thin inner layer of plastic for strength and insulation, and a layer of paper for easy unrolling and handling. These layers work together to provide the foil with its flexibility, strength, and ability to retain heat.