Abstract: A vacuum seal designed for the continuous movement therethrough of fibrous materials, such as carpet yarn, into a gaseous-plasma vacuum system while preserving a vacuum of about 1 Torr is described. The seal comprises a lower metal block with an elongated groove formed in the flat upper surface thereof and an upper metal block having an open bottom air chamber formed in its lower flat surface. In its assembled form, a flexible membrane is positioned between the formed, flat surfaces of the blocks. A seal is formed by pressurizing the air chamber in the upper block, thereby forcing the flexible membrane against the groove in the lower block and the upper side of the material passing therethrough, thus forcing the material to conform to the shape of the groove. Continuous variation in the degree of vacuum seal may be achieved by varying the pressure in the air chamber in the upper block.