GORE-TEX membrane is a microporous film of polytetrafluoroethylene which is inert and contains no harmful additives. Because it allows water vapor transmission and has excellent particulate filtration efficiency it is used on the faces of a novel humidity buffering device for a sealed compartment. This product is the GORE-TEX Silica Tile, manufactured by W.L. Gore & Associates, Elkton, MD. A calculation method was developed to determine the number of tiles needed. Involved are such variables as the humiditydifferential between the inside and outside of the compartment; compartment volume; leak rate; days of desired humidity control; and the moisture buffering capacity of the tile. The impact of these variables on the number of tiles needed is discussed. A sample calculation shows that 15 tiles are required to maintain 50±5per thousand at a leak rate of one-half air change per day for 60 days in a one-cubic meter compartment.