The techniques being used to measure the oxygen transmission rates of packaging films under humid conditions are briefly described and their advantages and disadvantages discussed. The techniques consist of various methods of humidifying the gas streams used in the standard methods for dry gas transmission rate measurements and the controlled humidity “sandwich” method. The new modern controls “H-System,” which was designed especially for this purpose, is also described.

One must choose from the available techniques and equipment based upon the needs and funds available. Only very limited data are available for comparison of the techniques, so accurate statements about precision still cannot be made.