(ASTM -D-1355) This test measures the force required to pull one yarn tuft out of the carpet. It determines how strong the adhesive bond is between the pile fiber and the adhesive back coating of the primary backing. In general, a single tuft of a loop pile carpet should withstand no less than 8.0 pounds of force. Cut pile tufted carpets have a minimum of 4.5 pounds. The test is conducted on an Instron or similar machine.