upholstery a pair of photo electric edge detectors 36 and 36a manufactured by idex corporation of northbrook ill are provided to sense the edge of the carpet backing or location of tuft area depending on their adjustment as carpet motion is detected by sensors 36 and 36a a signal is sent from the idex sensor to the idex controller 28 by signal wire 56 which in turn operates valves and an air oil system to position the end seal pistons 32 and 32a the stain rating of the carpets top bottom of the tufts is measured according to the method outlined in vinod u s pat no 4 925 707 the disclosure of which is hereby incorporated by reference the depth of stain protection is assessed by cutting a random sample of full length tufts at their base from across the width of the carpet with a razor blade or removing the tuft from the backing by hand the tufts are then stained per the test described in vinod u s pat no 4 925 707 the depth of stain protection is then determined by measuring the distance from the point where the stain resist agents are applied to the point where visible stain is observed in the following examples a solution having a total solid concentration of 2 by weight du pont sr 100 which is a mixture of styrene maleic.