Problems and Suggestions of Method Standards in Textile Testing1

In the long-term textile product testing work, the testing personnel found that some method standards have problems in actual operation, mainly including the selection of test conditions in the standard, the calibration of instruments, the rounding of numerical values, the interpretation of calculation formulas and some testing operations. How to deal with specific details, etc. These problems may directly affect the consistency and comparability of testing among testing personnel or testing institutions, and even directly affect the determination of product testing results. 1. Test method for pilling and pilling of fabrics 1. Circular track method“Test conditions”GB/T 4802.1—The selection and classification of test conditions in the 2008 'Textiles - Determination of Pilling Properties of Fabrics - Part 1 - Circular Locus Method' standard is not clear, resulting in a fabric that may have multiple test conditions to choose or unconditional to choose. If the A test conditions of this standard are applicable to sportswear, the B test conditions are applicable to synthetic fiber filament fabrics, while for sportswear made of synthetic fiber filament fabrics, both test conditions A and B can be used. However, for fabrics made of pure chemical short fibers and pure cotton, pure silk and other fabrics, if they are classified according to this standard, they are unconditionally optional. Although the remarks of the standard indicate that other fabrics not listed can refer to similar fabrics listed in the table or select the parameter category as agreed by the parties concerned, but different test personnel or inspection agencies may choose different test conditions, which brings great influence to the operation. Uncertainty makes test results not comparable. Therefore, it is recommended to classify the applicable fabric types of the test conditions of this standard more clearly and carefully to avoid the occurrence of the above situations. 2. The pilling performance of the calibration instrument among the four standards for fabric pilling“reference fabric”GB/T 4802.1—2008 'Textiles - Determination of pilling properties of fabrics - Part 1: Circular locus method' and GB/T 4802.3—2008 'Textiles - Determination of pilling properties of fabrics - Part 3: Circular locus method' standard specifies the method for checking the pilling degree of the pilling instrument.“reference fabric”.“reference fabric”For each set of 2 to 3 fabrics (from grades 1 to 2 to 4), to be used periodically or when required as a comparison initial standard to judge the degree of change in the pilling effect of the instrument. At present, the pilling effect of the two pilling methods produced by various instrument manufacturers is quite different, especially the pilling pilling instrument with circular trajectory, but there is no uniform fabric as“reference fabric”or“standard material”It is difficult to control and compare the pilling effect between different instrument manufacturers or even different table pilling instruments produced by the same instrument manufacturer, and it is also difficult to guarantee the pilling instrument used between the testing institutions. consistency of pilling performance. From the data of the comparison results between laboratories, it can be seen that the difference in the test results of the pilling item between the testing institutions can reach 1.5 grades, which shows the seriousness of the problem. Therefore, I personally suggest that the reference material production unit should design and produce a set of reference materials as soon as possible to unify the pilling performance of the pilling and pilling instruments of each testing institution and each instrument manufacturer, so that the testing results between the testing institutions are comparable. 3. Rounding off of pilling test results GB/T 4802.1-4 'Determination of Pilling Properties of Textile Fabrics' stipulates that the calculation method of the sample's rating result is: the rating result of a single person is the same as the rating of all samples. The average value, the test result of the sample is the average value of the ratings of all personnel, if the average value is not an integer, it is rounded to the nearest 0.5. There is no rounding rule specified here. When the decimal part of the average value is exactly 0.25 or 0.75, there can be two rounding results for rounding up to the nearest 0.5 level, and the final results reported by different personnel or different institutions may be inconsistent. For example, the 3.25 level can be rounded off to the nearest 0.5 level, which can be rounded to 3.5 level or 3.0 level. In the case where the test results, the evaluation grades of the samples, and the number of people involved in the evaluation are all the same, the test results may differ by 0.5 grades only because the rounding rules are not clearly specified in the standard. If the test result of the product is just at the critical value of qualified and unqualified, the result of unqualified judgment may also be caused by different rounding methods. It is recommended that the rounding method be clearly specified in the standard. For example, round off according to GB/T 8170 'Rules for Rounding of Numerical Values ​​and Representation and Judgment of Limit Values', or refer to GB/T 8427-2008 'Color Fastness Test of Textiles: Color Fastness to Artificial Light: Xenon Arc' The method of rounding is specified in Clause 8.2 of , taking the arithmetic mean of the grades as the result, and specifying that it is expressed in the nearest half-grade or whole grade, when the arithmetic mean is one-quarter or three-quarters, The evaluation should take the adjacent higher half grade or grade, that is, 3.25 is rounded off to 3.5; 3.75 is rounded off to 4.0. In this way, the modification methods of each testing personnel can be kept consistent, and the consistency of testing results can be ensured.

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