T 523 "Dynamic measurement of water vapor transfer through sheet materials" has been withdrawn for technical reason by its Standard-Specific Interest Group (SSIG). Because is was withdrawn technically, it will no longer be available for distribution.
The reason for withdrawal is that there is an ASTM method, ASTM E 96, for water vapor transfer of thermal insulation and applies to several types of materials including paper. There appears to be a lack of interest in developing an equivalent TAPPI method since the ASTM method is in use.