What is wvtr and otr for aluminum foil roll?

Aluminum foil provides a complete barrier to light, oxygen, moisture and bacteria. For this reason, foil is used extensively in food and pharmaceutical packaging. It is also used to make aseptic packaging that enables the storage of perishable goods without refrigeration.

How to judge the barrier ability of aluminum foil? there are two technical data simply called wvtr and otr.

Parameters such as oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) are used to test the amount of oxygen and moisture that enters the carton packages. These rates when low, indicate good barrier properties.

Generally, aluminium foil (ALU 7) has a WVTR between 0- 1g/m2/24hrs,

OTR aluminum foil is 0-1 cm3/m2/24hrs.