The Measurement of Carpet-pile Thickness Part II: Proposals for an Improved Pile-thickness Test Method

The existing standard test method of the International Organization for Standardization (ISO) for measuring the thickness of carpet pile above the backing requires that carpet total–thickness and backing–thickness measurements be made to the nearest 0.1 mm and the mean measurements quoted to the nearest 0.1 mm. There is no requirement to quote the precision of the mean, however, and that mean is frequently very imprecise owing to the often–variable nature of individual thickness measurements. The mean of a sample could be determined with a high precision by making large numbers of measurements, but the test would then become unduly time–consuming and expensive in view of the inherent variability in carpet production. Large numbers of pile–thickness measurements can readily be made by the WRONZ Pile Thickness Probe. This was done in the course of an international inter–laboratory trial, which indicated how the instrument could be used in a test method designed to provide measurements of mean pile thickness to a fixed or known precision. A basis for such a test method is given, and proposals are made as to how the method should be implemented.