A comparative study of the F-739 ASTM permeation test method and the gravimetric test method using different types of gravimetric permeation cells was performed. Two aluminum gravimetric cup cells and one commercial glass jar was used. Independent of the type of gravimetric permeation cell used, breakthrough time and permeation rate values obtained using the gravimetric method are equivalent to those obtained using the ASTM method. Problems with safe handling and with the cell seals were found with the first type of cup cell tried. A new type of conical cell that is easier to handle was developed.