When considering the durability of hosiery, abrasion re- sistance of the knit is an important factor. The more the tights can withstand rubbing action from, for example, a foot moving inside a shoe, a foot walking on a rough surface, or thighs rubbing against one another while walking, the more wears it will on average provide. Resistance to abrasion in fabric is typically measured using the Martindale method (ISO 12947 [1]). Under this method, the tested fabric is rubbed onto a standard abradant at relatively low pressure in continuously changing directions, tracing a Lissajous figure. Assessments—for example appearance change or specimen breakdown—are made after a predetermined number of rubs.

In prior testing, it was found that the standard Martindale method is not suitable for assessing abrasion resistance in tights. Firstly, the standard wool abradant is not sufficiently abrasive to produce a meaningful damage to the tights, even after 25,000 rubs. Secondly, the abrasion applied by the Martindale tester is not representative of the friction that occurs when worn by a user.

A Robot Arm Abrasion tester was specifically designed to more accurately mimic rubbing that would occur when the foot of a user wearing tights is moving inside a shoe, or when the wearer is walking on a rough surface. The robot arm used was a Universal Robots UR-5ETM (Cobots Intelligence inc.), mounted to a table. A custom adapter was fabricated to attach a model foot to the end of the arm as an end effector. The model foot was made of solid foam overlaid with silicone, providing it a feel similar to that of a human foot. A camera was set up such that the arm’s digital outputs could control the shutter, allowing for photos to be taken automatically of the top and bottom of the foot between rubbing cycles.

Additionally, a Martindale apparatus (James Heal 1605 Midi-Martindale with five stations) was used, with the intent of providing a middle ground between the testing standard and a completely novel test.

The Martindale method (ISO 12947 [1]) was used to assess abrasion resistance of tights, using the James Heal 1605 Midi- Martindale instrument. Instead of using the standard wool abradant, a more abrasive surface was used, Norton ProSand 320 Grit. The abradant was fixed using the ring clamp, and the felt backing fabric was omitted. The 9KPa weight was used. Tested samples were visually inspected using a progressive checking schedule - after 25, 50, 75, 100, 200, 300, 400, 500, 1000, 2000, 3000, 4000, 5000, and 10000 rubs. After 1000 rubs, any abraded fabric debris was cleared from the sample holders while checking the material.

Four stations were used, and a separate test was conducted for each brand. Samples were determined to have failed (and were thus removed from the apparatus) when visible holes appeared in the fabric. When all samples failed, the test was stopped.

There are several modes of fabric failure, which include but are not limited to fuzzing, pilling, and holes. When subjected to abrasive testing, most competing brands of tights immedi- ately developed holes, and completely bypass the fuzzing and pilling stage in this test.

As a longer-lasting fabric, the Sheertex knit did develop some fuzzing and (eventually) pilling, the fabric remained structurally intact and without holes for several thousand cycles, indicating that while there may eventually be visible wear in the fabric, it will continue to withstand wear for longer than the competition.

From these tests, it can be concluded that Sheertex tights are significantly more durable to abrasive breakdown. From the point of view of the consumer, and the environment, this substantial increase in resilience is a definite advantage. Tights which can better withstand these abrasion tests are also more likely to withstand the rigors of daily life, and many more wears than competitor tights, resulting in less waste and less inconvenience.

Many thanks to Amy Dam, Amanda Fleury, and Charlotte Fauqueux for their assistance with editing and adding clarity to this report.