The following post is republished from the Association for Contract Textiles. The study was researched and written by the ACT Technical Committee.
For some time the contract textile industry has been disconcerted by the variability of Wyzenbeek Performance test results. Results can and do vary significantly even when the same fabric is tested at different labs or on different machines.
The ACT technical committee decided to address this test variability by developing a fabric that would serve to verify the performance of a properly set-up Wyzenbeek test machine. The idea was that this fabric would be designed/manufactured in such a way as to fail within a consistent range of double rubs.
"Results can and do vary significantly even when the same fabric is tested at different labs or on different machines."
Such a fabric was engineered by Alan Dean and generously woven by True Textiles, and when tested in their own facilities, seemed to meet this goal.
The next step was to evaluate this fabric in a controlled study. Seven different industry laboratories conducted the controlled verification fabric study during the summer of 2009. It was hoped the study results would provide a scientific basis for recommending this fabric as a tool to verify performance of testing machines and therefore reduce the known variability of the test method.
The technical committee was astonished by what the study revealed. Although the expected variation from lab to lab and machine to machine did occur, there was a wide and unexpected variation of results on the same arms of the same machines in repeated tests. The termination of the test was set at 50,000 double rubs, at which point many specimens did not fail. Note that the variation would most likely have been even higher if tests had been run to the first two yarn breaks. Each lab reconfirmed that their Wyzenbeek abrasion machines were set up according to the ASTM D 4157 protocol. While atmospheric conditions can be a source of variability, heat and humidity alone cannot be responsible for the wide variations seen within the same lab in this study. The technical committee concluded that the performance verification fabric would not be useful as a tool to reduce the amount of variability inherent in the test method, and suspended further research.
In light of this conclusion, the ACT technical committee and ACT board of directors recommends better education of the A&D community. This document is the second in a series of three white papers and is intended to be read in conjunction with the other two: Abrasion Resistance: The Full Story and ACT Industry Survey on Durability. Educating specifiers to evaluate all aspects of durability will enable them to be less dependent on Wyzenbeek testing and double-rub numbers.