Circular locus, modified Martindale, pilling box, and random rolling pilling methods in the GB/T 4802-2008 series Chinese national standard “Textiles: Determination of fabric propensity of surface fuzzing and to pilling” were compared.

By Yan Shen, National Textile and Garment Quality Supervision Testing Center (Fujian) and Fujian Fiber Inspection Institute

Note: This paper was originally published in China Fiber Inspection Journal, January 2010. Translation provided by China Fiber Inspection Bureau. Used by TESTEX Textile Instrument Ltd

Abstract

Circular locus, modified Martindale, pilling box, and random rolling pilling methods in the GB/T 4802-2008 series Chinese national standard “Textiles: Determination of fabric propensity of surface fuzzing and to pilling” were compared.

The pilling resistance of the same fabric, tested by the same method under different testing conditions, varied by about 1.5 grades. Different methods produced results varying by almost two full grades. Differences between the national standards (GB/T series) and textile industry standards (FZ/T series) are discussed. Suggestions are given for further standardizing the standards.

Key Terms: Comparison, Fuzzing, Pilling, Standard, Test

Introduction

The fuzzing and pilling resistance of fabric is an important factor that affects the wearability of clothing. It will seriously affect the appearance performance of textile fabric [1]. Thus, a variety of methods have been developed to appraise and determinate this property.

In 2008, the National Technical Committee 209 on Textiles of Standardization Administration of China (SAC/TC 209) issued three national standards: GB/T 4802.1-2008 Textiles: Determination of fabric propensity of surface fuzzing and to pilling—Part 1: circular locus method, [2] GB/T 4802.2-2008 Textiles: Determination of fabric propensity of surface fuzzing and to pilling—Part 2: modified Martindale method, [3] and GB/T 4802.3-2008 Textiles: Determination of fabric propensity of surface fuzzing and to pilling—Part 3: pilling box method [4]. These replaced the 1997 versions of each standard. GB/T 4802.4-2009 Textiles: Determination of fabric propensity of surface fuzzing and to pilling—Part 4: random rolling method [5] was approved June 19, 2009 and implemented February 1, 2010. Using these four methods, experiments have been done under a variety of test conditions. Corresponding test results have also been compared and analyzed. The logic of standard requirements, the scientific rationale for testing methods, and the replacement of old and new standards are discussed. Comparisons of Four Testing Methods are given in Table I.

Table I. Theories and Equipment of Four Testing Methods

Analysis and Comparison

Worsted woven fabric, semi-worsted woven fabric, wool woven fabric, and knitted fabric were chosen to do experiments. Two testing schemes: 1. the same testing method under different testing conditions; 2. the same fabric under four testing methods were used to do the following test.

Testing Results of GB / T 4802.1-2008

The worsted woven fabric and semi-worsted woven fabric were tested according to the six testing conditions (A-F) of the GB/T 4802.1-2008 standard. The specific experimental parameters and test results are shown in Table II.

Based on results in Table II, testing condition A was the most severe and F was the least severe. For the same fabric, under different testing conditions, the pilling resistance results varied by up to 1.75 grades and the mean variation was 1.5 grades.

Testing results of GB / T 4802.2-2008

The testing conditions in GB / T 4802.2-2008 standard include multiple loading weights (415 or 155 g), abradants (standard woolen fabric or test fabric itself), and rubbing times (six stages). To study these three factors, three experimental schemes were designed (Table III).

Four samples were tested under the conditions shown in Table III; results are shown in Fig. 1. Scheme #2 specimens were consistently rated lowest, indicating the most severe rubbing. Scheme #1 specimens were almost always rated highest.

The degrees of specimen pilling resistance, evaluated by comparing the tested specimens with visual standards, varied with the abradant. Comparison of Schemes #2 and #3 (same loading weight, different abradant) indicated that more pilling occurred when the abradant was the fabric itself (Scheme #2) than when the standard woolen fabric abradant was used (Scheme #3). The average difference was about 0.5 grades.

Based on Scheme #1 and #2 results (same abradant, different loading weight), it can be seen that the degrees of pilling resistance also varies with loading weight. Specimens tested with the 155-g loading weight were graded about one grade higher than those tested with the 415-g loading weight. Comprehensive comparison of all three schemes shows that the loading weight is more important than the abradant for the fabric pilling resistance.

The number of rubs, regardless of loading weight or abradant type, also affected the testing results. For all schemes, the pilling resistance grades declined with the gradual increase in number of rubs under the GB/T 4802.2-2008 standard. The loading weight can cause a one-grade difference in pilling resistance of the same fabric, while the number of rubs can cause 2.5 grades difference.

Results for Four Methods

The three kinds of fabrics were tested according to four testing method under specific experimental conditions. The experimental conditions and results were shown in Table IV.

From Table IV, the methods can be ranked in terms of expected pilling resistance grade. For woven fabrics: Circular locus method > Random rolling method ? Modified Martindale method. For knitted fabric: Pilling box method > Random rolling method > Circular locus method = Modified Martindale method. The friction on a specimen’s surface in the circular locus method and modified Martindale method were similarly severe. The friction of the pilling box method was slightest and the random rolling method was in between.

The pilling resistance of the same fabric with various testing methods was quite different. For semi-worsted woven fabric, the difference of pilling test results between circular locus method and modified Martindale method was close to two grades. For knitted fabric, the grade of pilling resistance for the pilling box method was one grade higher than that for the circular locus or modified Martindale methods.

Discussion of Test Methods

Circular Locus Method

The classification and choice of test conditions in the GB/T 4802.1-2008 standard is not clear. For example, testing condition A was suitable for sportswear and testing condition B was suitable for synthetic filament fabric. So, sportswear made from synthetic filament fabric can be tested under A or B. Pure chemical, short-fiber cotton, and silk fabrics do not fit any of the classifications in the standard, so was no clear guidance in selecting suitable testing conditions. The standard did have notes stating that unlisted fabrics can reference the conditions indicated for similar fabrics or experimental parameters may be agreed upon by all parties. The authors of this paper recommend that the testing conditions and suitable fabric types should be made clearer in the standard to avoid confusion.

The pilling resistance of the same fabric tested under various conditions was quite different. The difference can reach 1.5 grades. When a fabric is tested for pilling resistance according to GB/T 4802.1-2008, the testing conditions (A-F) should be indicated. This will define the testing and make results comparable. It will also ensure that the test performance indicators or requirements are practical.

There are some differences between similar tests in the national standards (GB/T series) and textile industry standards (FZ/T series). For example, for knitted sportswear, the specified testing parameters in the FZ/T 73007-2002 standard are: 780 g loading weight, 0 fuzzing, and 600 pilling. This is equivalent to the E condition in the GB/T 4802.1-2008 standard. However, much knitted sportswear is made of synthetic filament fabric, which would be tested according to the conditions: 590-g loading weight, 50 fuzzing, and 50 pilling in the GB/T 4802.1-2008 standard (B condition). Therefore, when a qualified fabric is chosen to produce a garment, it may really be unqualified. Agreement between the national standards and the textile industry standards is suggested.

Modified Martindale Method

For non-decorative woven and knitted fabric, the abradant was the fabric itself or a standard wool abradant fabric in the GB/T 4802.2-2008 standard. The testing results for these two abradant types were quite different, although the number of rubs was the same. Different numbers of rubs also got different testing results. So, when the GB/T 4802.2-2008 standard is selected to evaluate the pilling resistance, it is proposed that the abradant type and the number of rubs should be indicated.

Three standards (FZ/T 62005-2003 Quilts and quilt cover, FZ/T 62007-2003 Sheet, and FZ/T 62009-2003 Cushion and pillow) referenced the GB/T 4802.2 standard for evaluation of pilling resistance, but the dates were not specified. According to “normative reference documents” in textile industry standards (FZ/T series), no date was indicated so the new version was suitable for this standard. However, there are great differences between the old and new versions of the GB/T 4802.2 standard as shown in Table V.

From Table V, it can be seen that the test specimen holder (inside diameter), loading weight, and motion trail are totally different between the two versions. There are six assessment stages in the new version. The number of rubs was not indicated in the three bedding standards listed above, so the experimental evaluation can not be done. If the number of rubs was 1,000 as in the 1997 (old) version, the contact area between specimen and abradant, decided by the inside diameter of test specimen holder, the loading weight, and motion trail are still different. Thus, the experimental results are not comparable and the assessment indicators became nonsense. Therefore, when the new standard replaced the old one, the pilling resistance for some products could not be assessed. The revising and improvement of these product standards for the textile industry is suggested.

Suggestions on Evaluation the Pilling Resistance for Some Product Standards

The pilling resistance of the same fabric with various testing methods was quite different. So choosing the suitable experimental method is really very important. From the above control experiments, for knitted fabric, the grade of pilling resistance for the pilling box method was one grade higher than that of the circular locus method. For some products, the pilling resistance requirements for the pilling box method, are the same or lower than for the circular locus method as seen in Table VI.

From the above table, the assessment indicators (requirements) for wool knitted goods are relatively low. The pilling box method, with its relatively slight friction condition, was selected as the testing method. Therefore, these products are easily qualified by textile industry standards (FZ/T series standards). In reality, there is pilling that affects the wearability of clothing. It is necessary to enhance the assessment indicators of wool knitted goods, low wool content, and wool-like knitted goods, or change the corresponding testing method.

Conclusions

From the above experimental results, several conclusions can be made.

§                    If a standard contains a variety of testing conditions which are suitable for different kinds of textile products, it is best to clearly classify the textile production.

§                    When the product standards (FZ/T series) references the national standards (GB/T series) to evaluate the pilling resistance, it is proposed that the testing conditions should be indicated.

§                    The indicators for product standards should relate to the assessment method. When the assessment indicators are relatively easy to reach, they should be raised to ensure product quality.

§                    If the national standards and the textile industry standard are all relate to relevant experiments, It should keep a combination of these two kinds of standards as far as possible that makes the standards more standardized.