lower portion of the drop wires is a vacuum chamber 50 having four walls disposed to draw air from the ambient atmosphere of the weave room across the drop wires 43 and the warp yarns 46 for removing all lint fly dust size oil or the like from the surfaces of the drop wires and for conditioning the warp yarn by concentrating the air from the ambient atmosphere onto such yarn just prior to its being subjected to its greatest stress during the weaving process i e the formation of the warp sheds and the beat up process the concentration of the air drawn from the ambient atmosphere on the warp yarn increases the moisture content of the warp yarn over that naturally absorbed by its passage through the unconcentrated ambient atmosphere this permits a lower relative humidity to be utilized in the ambient atmosphere for a given moisture content in the warp yarn vacuum chamber 50 extends the length of the warp stop motion and has walls which partially surround the drop wires at one end of the vacuum chamber 50 is an exhaust pipe or duct 52 exhaust duct 52 extends down the side of the weaving machine and extends.