The experts make it clear: the open chamber method of the Tewameter® is the best
The EEMCO Group (European group on efficacy measurement and evaluation of cosmetics and 
other products) is back with its latest guideline on the very important skin water measurements.
The recently published guideline (Skin Research & Technology, 2018, 24, p. 351-358)
other products) is back with its latest guideline on the very important skin water measurements. The recently published guideline (Skin Research & Technology, 2018, 24, p. 351-358)
considers all existing and new methods for the measurement of the skin barrier. The experts say: ..."From skin barrier damage experiments, it became clear that the Tewameter with an open-chamber is more sensitive or disiminative and able to detect significantly smaller differences than the VapoMeter. In addition, the closed chamber device is currently not sensitive enough to measure diurnal rhythm and fluctuations of skin as a function of time. ... Thus, the closed chamber instrument is inferior to the open-chamber measurement of TEWL ...".
In the guideline also Corneometer® and MoistureMap are mentioned.