The first volume offers comprehensive information about the technology of instruments and the art of applying them in experimental settings. For example, it - an overview of the ultrastructure and biochemistry of the epidermal barrier - an explanation of the instruments for measuring transepidermal water loss and epidermal moisture - guidelines for standardization of measurements and communication of results - review of current knowledge on epidermal water and transepidermal water loss in health and disease - instruction by experienced investigators about how to perform product testing with these instruments