By guest author Diana Wyman from AATCC, the American Association of Textile Chemists and Colourists
New guidelines for writing AATCC test methods will help your supply chain make quicker, more informed decisions. Here are some additional information on how to use the test methods to avoid any mistakes
It is no secret that standardized test methods are incredibly detailed. Some might even say overwhelming—with entire sections for terminology, calculations, and statistics.
Believe it or not, there are no wasted words. Every section of a test method, evaluation procedure, or other standard has a purpose. But certain sections may be more important to some readers than to others.
If you are performing the test, read every section carefully. Do not skim over sections like Safety Precautions, Conditioning, or Precision. Be sure you are using the most recent version of the standard (see http://www.aatcc.org/test/methods). Pay attention to details like tolerances and significant digits. If you find unclear, incorrect, or missing information, contact AATCC to ask a question or suggest a revision. AATCC standards are some of the most robust in the world because of the input of experts—like you—from across the industry.
If you are ordering a test or reviewing a report, you may not need quite as much detail. It is still helpful to have a good understanding of the method to determine whether it is applicable and how to interpret the results. This is where the new guidelines will be most valuable. Read the Foreword, Purpose and Scope, and Principle sections at the beginning of each standard to get an overview of when and how they should be used. The content of these sections is available at no cost, simply by clicking the standard number at www.aatcc.org/test/methods
You will be seeing more AATCC standards that start with a Foreword. Forewords are “a history of the rationale for the development of the method.” This means an explanation of why the standard was developed and how it relates to similar standards.
For example, AATCC TM124, Smoothness Appearance of Fabrics after Home Laundering, explains, “This test method and its accompanying three-dimensional smoothness appearance replica set were developed for evaluation of woven fabrics with a durable press finish. It is common industry practice to use the method and scales for evaluation of other textile materials although some specimens may have different appearance characteristics due to different fabric constructions.” Knowing the method was developed for durable press fabrics makes it easier to understand why it is difficult to consistently evaluate lightweight knit fabrics.
AATCC TM207, Seam Twist in Garments Before and after Home Laundering, clarifies differences among several test methods to help the user choose the one most applicable to his or her needs. “TM207 is for evaluation of seam twist before and after home laundering. TM179, Skew Change of Fabric or Fabric in Garments After Home Laundering, is to be used to evaluate the change in fabric skew after home laundering. ASTM D3882, Standard Test Method for Bow and Skew of Woven and Knitted Fabrics is only to be used to evaluate fabric skew in its original state (before laundering).
Some of the most important changes to the AATCC Style Guide relate to the Principle section. This section has always called for test methods to “Briefly state the testing technique covered in the test method, outlining the fundamental physical and chemical concepts involved.” This should be a very simple overview of the procedure—not enough detail to perform the test, but enough to get the general idea. In case you have never seen the word “crocking,” the Principle section of TM8, Colourfastness to Crocking: Crockmeter Method, provides a concise description of the method: “A coloured test specimen is rubbed with a white crocking test cloth under controlled conditions.”
Now, the Principle section should also include “the metric or scale for reporting results, (e.g., Results are reported as a Gray Scale for Colour Change grade of 5 to 1, with 5 representing no colour change and 1 representing the most colour change.)” This means anyone can pick up a report, review the test method Principle and have some idea of what the test results mean. A colour change grade of 3 makes more sense when you understand it is on a scale of 5 to 1, not out of 10 or 100. Understanding the direction also makes a difference. Without explanation, it may not be obvious that a grade of 3 means less colour change than a grade of 2.
Of course, every test method won’t be updated immediately to reflect the revised Style Guide. AATCC standards are reviewed at least once every five years. As documents come due for review, the responsible research committee will review formatting and clarity as well as technical content. Committees should ballot revisions as needed to match the current Style Guide. AATCC staff and members of the RA99, Technical Manual Editorial Review committee are available to help with this process. To join a research committee, visit www.aatcc.org/test/committees