results for a non impregnated fabrics b for fabrics pre impregnated with viscose and c for fabrics pre impregnated with resin the samples were treated at constant specific power and treatment time with varying concentrations of h 2 o vapor the criterion used for comparing effectiveness of the treatment is the time required for absorption of liquid viscose and water to a height of 25 mm in a treated sample suspended over the liquid the results show that also for these materials the presence of water vapor in the inorganic gas plasma enhances the surface property modification process in comparison to the analogue samples treated without water vapor a 150 150 mm sample of wool fabric with specific density 820 g m2 was placed into a plasma discharge chamber equipped with external cylindrical electrodes air was extracted by a vacuum pump to a pressure of 0 005 torr oxygen gas with water vapor added to a concentration of 0 1 was then introduced into the chamber to a pressure 0 5 torr a glow discharge was ignited by supplying high frequency voltage at 6 25 mhz to the electrodes for 120 sec with specific power input of 0 35 wt cm3 the discharge was then extinguished and vacuum pumping stopped air was admitted into the system and the sample removed from the discharge chamber the sample subjected to testing after treatment showed substantially unimpaired mechanical properties air penetration of the untreated sample was measured as 24 9 cm3.