Test Method D 1335 for tuft bind of pile yarn floor coverings is being used for acceptance testing of commercial shipments. Comparative tests as directed in 5.1.1 may be advisable.

5.1.1 In case of a dispute arising from differences in reported test results using this test method, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended from the investigation of bias. As a minimum, the two parties should take a group of test samples that are homogeneous as possible and are from a lot of material of the type in question. The test samples should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using appropriate statistical analysis, and a probability level chosen by the two parties before testing begun. If a bias is found, either its cause must be found and corrected or the purchaser and the supplier must agree to interpret future test results with consideration to the known bias.

The satisfactory performance of a pile yarn floor covering depends to a considerable extent on the maintenance of its original appearance. In a cut pile yarn floor covering an inadequate tuft bind may result in complete loss of pile in areas exposed to severe wear. In a looped pile yarn floor covering with inadequate tuft bind the pile loops may be pulled out to form unsightly long loops which may be hazardous.

FIG. 1 Metal Specimen Holder, Cut-Away Type