AATCC Technical Manual/2020
AATCC TM8-2016e 21
Developed in 1936 by AATCC Commit-tee RA38; revised 1937, 1952, 1957,1961, 1969, 1972, 1985, 1988, 1996,2004, 2005, 2007, 2013, 2016; reaf-firmed 1945; 1989; editorially revised and reaffirmed 1968, 1974, 1977,1981, 1995, 2001; editorially revised 1986, 2002, 2008 (with title change),2009, 2010, 2011, 2019. Partly equiva-lent to ISO 105-X12.
1.Purpose and Scope
1.1 This test method determines the amount of color transferred from the sur-face of colored textile materials and other dyed materials (i.e., leather) to other sur-faces by rubbing.
1.2 Test procedures employing white crocking cloth squares, both dry and wet with water, are given.
2.Principle
2.1 A colored test specimen is rubbed with a white crocking test cloth under controlled conditions.
2.2 Color transferred to the crocking cloth is assessed by a comparison with the Gray Scale for Staining (AATCC EP2), the AATCC 9-Step Chromatic Transference Scale (AATCC EP8), or Instrumental Assessment of Degree of Staining (AA TCC EP12), and a grade is assigned.
3.Terminology
3.1 colorfastness, n.—the resistance of a material to change in any of its color characteristics, to transfer of its color-ant(s) to adjacent materials, or both, as a result of the exposure of the material to any environment that might be encoun-tered during the processing, testing, stor-age or use of the material.
3.2 crocking, n.—a transfer of color-ant from the surface of a colored yarn or fabric to another surface or to an adjacent area of the same fabric principally by rubbing.
4.Safety Precautions
NOTE: These safety precautions are for information purposes only. The pre-cautions are ancillary to the testing proce-dures and are not intended to be all inclu-sive. It is the user’s responsibility to use safe and proper techniques in handling materials in this test method. Manufac-turers MUST be consulted for specific details such as material safety data sheets
and other manufacturer’s recommenda-tions. All OSHA standards and rules must also be consulted and followed.4.1 Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.5.Uses and Limitations
5.1 This method is not recommended for use for carpets or for prints where the singling out of areas may be too small us-ing this method (see 14.1 and 14.2).
5.2 Since washing, drycleaning,shrinkage, ironing, finishing, etc. may af-fect the degree of color transfer from a material, the test may be made before, after,or before and after any such treatment.5.3 This method is designed for use with an AATCC crocking cloth as de-scribed in 14.5. Alternatively, other adja-cent textile substrates may be used as agreed between interested parties.
6.Apparatus and Materials (see 14.3)
6.1 Crockmeter (see 14.4 and Fig. 1).6.2 AA TCC Crocking Cloth, cut in 50 ±1 mm squares (see 14.5).
6.3 AA TCC 9-Step Chromatic Trans-ference Scale (AATCC EP8) (see 14.6).6.4 Gray Scale for Staining (AATCC EP2) (see 14.6).
6.5 White AATCC Textile Blotting Paper (see 14.6).
6.6 Specimen holder for crockmeter.6.7 Spiral wire clip for securing crock-ing cloth to crockmeter finger.
6.8 Crockmeter verification fabric, or in-house fabric with known poor color-fastness to crocking properties, that pro-vides repeatable and predictable crocking results.
6.9 Emery paper to provide friction on the base of the crockmeter (see manufac-turer’s recommendations).
7.Verification
7.1 Verification checks on the opera-tion of the test and the apparatus should be made routinely and the results kept in a log. The following observations and corrective actions are extremely impor-tant to avoid incorrect test results where abnormal crock images can result and in-fluence the rating process (see 14.7).7.2 Use the crockmeter verification fabric or in-house poor crocking fabric with known predictable and repeatable crocking behavior and conduct three dry and wet crock tests.
7.2.1 A poor circular image with un-even dye pick-up may indicate the crock-ing finger needs resurfacing (see 14.8).7.2.2 A double, elongated image may indicate a loose clip (see 14.8).
7.2.3 A stretched and streaked crock image may be due to mounting the crock square diagonally.
7.2.4 Scuff marks to the sides of the specimen indicate the loops of the wire clip are positioned downwards and are not high enough to prevent rubbing the specimen surface.
7.2.5 A streak in the center of the crock cloth image and in the direction of rub-bing may indicate damage to the metal base of the device. Contact the manufac-turer for recommended solution.
7.2.6 If specimen holder is used, place the holder over the specimen on the tester base. V erify that the holder is not imped-ing the motion of the finger or coming in contact with it in any way, adjust the holder as necessary to ensure free move-ment. Without correction, this problem will cause a dark area on one side of the crocking image.
7.2.7 Confirm the wet pick-up tech-niques (see 10.2).
7.2.8 Replace the abrasive paper on the tester base if it is smooth to the touch in the crocking area compared to the adja-cent area, if slippage of the specimen is noticed or if any ridges or bumps are no-ticed.
7.2.9 In routine testing, observe if mul-tiple streaks are on the crocking image.Position specimen norm
ally with the long dimension oblique to the warp and fill-ing. If the direction of rubbing falls along a twill line or surface pattern, etc., then streaks may occur. If they do occur,slightly adjust the angle for testing.
AATCC TM8-2016e
Test Method for Colorfastness to Crocking: Crockmeter
Fig. 1—Crockmeter.
Copyright © 2019 American Association of Textile Chemists and Colorists
22AATCC TM8-2016e
AATCC Technical Manual/2020
8.Test Specimens
8.1 Two specimens are used, one each for the dry and the wet tests.
8.1.1 Additional specimens may be used to increase the precision of the aver-age (see 13.1).
8.2 Cut the specimens at least 50 × 130mm and position for testing preferably with the long dimension oblique to warp and filling or wales and courses (see Fig. 2).8.2.1 Larger or full width lab samples may be used without cutting individual specimens, when multiple tests are needed and when using for production testing. Wherever possible, large samples should be positioned obliquely. If this is not possible, make a note in the report.Avoid seams and other raised areas.
8.2.2 Samples should be prepared in an oblique direction to the warp and weft,neither parallel, right angled or at 45°;they should be slanted.
8.3 Yarns. Knit a piece of fabric at least 50 × 130 mm and position as per 8.2, or wind yarn tightly on a suitable sample card/plate at least 50 × 130 mm,with the yarn running in the long direc-tion (see 14.9).9.Conditioning
9.1 Prior to testing, precondition and condition the test specimens and the crocking cloth for crock testi
ng as di-rected in ASTM D1776, Standard Prac-tice for Conditioning and Testing Tex-tiles. Condition each specimen for at least 4 h in an atmosphere of 21 ± 2°C (70 ±4°F) and 65 ± 5% RH by laying each test specimen or crock square separately on a screen or perforated shelf of conditioning rack.10.Procedures
10.1 Dry Crocking Test.
10.1.1 Place a test specimen on the base of the crockmeter, flat on the abra-sive cloth, with its long dimension in the direction of rubbing.
10.1.2 Place specimen holder over
editoriallyspecimen and apply sufficient tension to avoid slippage or wrinkling.
10.1.3 Mount a crocking cloth square,the warp or weft direction parallel to the direction of rubbing, over the end of the finger that projects downward from the weighted arm. Use the spiral wire clip to hold the square in place. Position the clip with loops upward. If the loops point downward, they can drag against the test specimen.
10.1.4 Lower the covered finger onto the test specimen. For manual crockmeters,beginning with the fin
ger positioned at the front end, turn the handle 10 complete turns at the rate of one turn per second to slide the covered finger back 10 times and forth 10 times. For motorized crockme-ters, set and run for 10 complete turns.Refer to individual specifications for any other required number of turns.
10.1.5 Remove the crocking cloth square, condition (see 9.1) and evaluate as directed in Section 11. In the case of napped, brushed or sanded material,when loose fiber might interfere with the rating, remove the extraneous fibrous material by pressing lightly on the crock circle with the sticky side of cellophane tape before evaluating.10.2 Wet Crocking Test.
10.2.1 Weigh a conditioned dry crock-ing cloth square. Calculate the desired wet weight (65 ± 5% pickup) by multi-plying the original dry weight by 1.65.Apply water evenly over the crocking cloth square and weigh to verify 65 ± 5%pickup. If necessary, discard the square with insufficient or excessive weight and use a new crocking cloth square. Repeat this process each day (see 14.10).
An example of how to achieve this pickup is: Using a syringe tube, gradu-ated pipette or automatic pipetter, draw up water in mL to 0.65 times weight of crocking square. Example: If the crock-ing square weight equals 0.24 g, the mL used would be 0.24 × 0.65 = 0.16 mL.Lay the crocking cloth square on white plastic mesh over a dish. If needed, adjust the amount of water used to wet the square and using
a new crocking cloth square, repeat steps. When 65 ± 5% wet pickup is achieved, record the amount of water used. Draw up the recorded amount of water into the syringe tube, graduated pipette or automatic pipette for each wet crocking performed during the current day. Other methods are available and can be used.
10.2.2 Avoid evaporative reduction of the moisture content on the crocking cloth square below the specified level of 65 ±5% before the actual crock test is run.10.2.3 Continue as directed in 10.1.10.2.4 Air dry the crocking cloth square, then condition (see 9.1) before evaluating. In the case of napped,brushed or sanded material when loose fi-ber might interfere with the rating, re-move the extraneous fibrous material by pressing lightly on the crock circle with the sticky side of cellophane tape before evaluating.
11.Evaluation (see 14.11)
11.1 Back the crocked square with three layers of clean crocking cloth for evaluating.
11.2 Rate the amount of color trans-ferred from the specimen to the crock square under examination by means of the AA TCC Gray Scale for Staining (AA TCC EP2), AA TCC 9-Step Chro-matic Transference Scale (AA TCC EP8)or Instrumental Assessment of Degree of Staining (AA TCC EP12) a
nd record the numerical rating (see 14.12 and 14.13).11.3 Average the individual results to the nearest 0.1 grade when multiple spec-imens are tested or when a panel of eval-uators rate color transfer.12.Report
12.1 State the grades of dry and wet crocking test, unless otherwise requested between parties.
12.2 Report the grade determined in 11.3.12.3 State whether AATCC EP2,AATCC EP8 or AATCC EP12 was used for evaluating staining (see 14.12).
12.4 If any pretreatment or aftertreat-ment was given to any specimens (see 5.2), indicate method of treatment.13.Precision and Bias (see 14.14)
13.1 Precision . An interlaboratory test was conducted in 1986 to establish the precision of the test method. Testing was conducted under the normal atmospheric conditions of each laboratory and not necessarily under ASTM D1776 standard conditions. Two operators at each of 12laboratories evaluated 5 fabrics in 3 repli-cations by both dry and wet test method.Each of 3 raters independently rated the stained crocking cloth squares using both
Table I—Components of Variance
Dry
Wet
Chromatic
Gray Chromatic
Gray Single Operator/Rater Within Laboratory Between Laboratory
0.200.200.10
0.200.190.17
0.240.310.38
0.250.340.54
Fig. 2—Oblique alignment of specimen (left).
Copyright © 2019 American Association of Textile Chemists and Colorists
AATCC Technical Manual/2020
AATCC TM8-2016e 23
the Gray Scale for Staining and the AATCC 9-Step Chromatic Transference Scale. The original data is on file at the AA TCC Technical Center.
13.1.1 The components of variance as standard deviations of the Gray Scale for Staining or AATCC 9-Step Chromatic Transference Scale rating units are given in Table I.
13.1.2 Critical differences are given in Table II.
13.1.3 Example for determining be-tween laboratory differences using one observer and the chromatic scale are given in Table III.
Interpretation: For the dry crock test,since the difference between labs is less than the critical differenc
es in Table II (0.82), the difference in results is not sig-nificant. For the wet crock test, since the difference between labs is greater than the critical difference (1.53), the differ-ence in results is significant.
13.2 Bias . The true value of colorfast-ness to crocking can only be defined in terms of a test method. Within this limita-tion, this test method has no known bias.14.Notes
14.1 For carpets, AATCC TM165, Test Method for Colorfastness to Crocking: Car-pets—Crockmeter, under the jurisdiction of Committee RA57, Floor Covering Test Meth-ods, should be used.
14.2 For prints where the singling out of ar-eas too small to test with the standard crock-meter is necessary (see AATCC TM116, Test
Method for Colorfastness to Cracking: Rotary Vertical Crockmeter). Specimens tested by both test methods may show dissimilar results.There is no known correlation between the two methods.
14.3 For potential equipment information pertaining to this test method, please visit the online AATCC Buyer’s Guide  at /bg. AATCC provides the possibility of listing equipment and materials sold by its Corporate members, but AATCC does not qualify, or in any way approve, endorse or cer-tify that any of the listed equipment or materials meets the requirements in its test methods.
14.4 The crockmeter provides a reciprocat-ing rubbing motion simulating the action of a human finger and forearm.
The crockmeter is so designed that the 16 ±0.3 mm diameter finger moves back and forth,with each complete turn of the crank, in a straight line along a 104 ± 3 mm track on the specimen, with a downward force of 9 ± 0.9 N (2 ± 0.2 lb).
14.5 AATCC Crocking Cloth should meet the following specifications:
Fiber
100% 10.3-16.8 mm combed cotton staple with no optical brightener present
Yarn 15 tex (40/1 cotton count),
5.9 turns/cm “z”
Thread count for greige fabric 32 ± 5 warp
ends/cm: 33 ± 5 filling picks/cm
Weave 1/1 plain
Finished fabric desized and bleached with no
optical brightener or finish-ing material present
pH 7 ± 1
Mass/sq meter 100 ± 3 g finished Whiteness W = 78 ± 3 (AA TCC TM110)14.5.1 CAUTION: ISO crock test cloth re-sults may not be equivalent to AATCC crock-ing cloth results/values based on crocking cloth study.
14.6 The AATCC 9-Step Chromatic Trans-ference Scale, Gray Scale for Staining and the White AATCC Textile Blotting Paper are available from AATCC, P.O. Box 12215, Re-search Triangle Park NC 27709; tel:+1.919.549.8141; fax: +1.919.549.8933; e-mail: ; web site:
14.7 For a discussion of crock testing, see the article by J. Patton, “Crock Test Problems can be Prevented,” Textile Chemist and Color-ist , V ol. 21, No. 3, March 1989, p13; and “Testing for Crocking: Some Problems and Pitfalls” by Allan E. Gore, Textile Chemists and Colorists , V ol. 21, No. 3, March 1
989,p17.
14.8 Accidental damage to the rubbing fin-ger, spiral clip or abrasive paper should be repaired as follows: neatly renew the abrasive paper; bend the clip further open or shut around a rod slightly smaller in diameter than the crock peg; resurface the finger by move-ment on an extra piece of fine emery cloth in a manner simulating regular use.
14.9 For more convenient crock testing of multiple strands of yarn or thread a dowel at-tachment is useful. This attachment was de-veloped to avoid the tendency of the standard finger to dig into and push aside the yarns, or slide off them and possibly give erroneous results. This attachment is 25 mm in diameter by 51 mm long. Positioned on its side and held in place by the standard finger, it provides a wider test area, and holds the white test square by two spring loaded clips. For additional in-formation on this development see the article by C. R. Trommer, “Modification of the AATCC Crockmeter for Yarn Testing,”American Dyestuff Reporter , V ol. 45, No. 12,June 4, 1956, p357; also see articles by S. Ko-rpanty and C. R. Trommer, “An Improved Crockmeter for Yarn Testing,” American Dye-stuff Reporter , V ol. 48, No. 6, March 23,1959, p40.
14.10 Experienced operators do not have to repeat this weighing procedure during a test session once the technique is established.
14.11 CAUTION: It has been reported that the results for staining obtained by this method on fabrics dyed to dark shades (navy,black, etc.) that contain a combination of poly-ester and spandex, or their blends, may not show the full staining propensity of such fab-rics in consumer use. It is, therefore, recom-mended that the staining results obtained by this test not be used for the acceptance testing of such fabrics.
14.12 It has been noted that different grades may result depending upon whether the Gray Scale for Staining or AATCC 9-Step Chromatic Transference Scale is used for the evaluation. It is, therefore, important to report which scale was used.
For very critical evaluations and in cases of arbitration, grades must be based on the Gray Scale for Staining.
14.13 An automated electronic grading sys-tem may be used as long as the system has been demonstrated to provide results that are equal to and provide equal or better repeatabil-ity and reproducibility than an experienced grader performing visual evaluation.
14.14 The precision of this test method is dependent on the combined variability of the material being tested, the test method itself,and the evaluation procedure utilized.
14.14.1 The precision statement in Section 13 was developed from results obtained by vi-sual evaluation.
14.14.2 It is expected that the use of instru-mental evaluation procedures will result in greater precision than that obtained from vi-sual evaluations.
Table II—Critical Differences
For the components of variance in Table I, two averages of observed values should be considered significantly different at the 95% probability level if the difference equals or exceeds the following critical differences.
No. of Observations
Dry
Wet
Chromatic Gray Chromatic
Gray Single Operator/Rater 1350.550.320.240.540.310.240.680.390.300.700.400.31Within Laboratory 1350.770.600.600.750.610.57  1.080.930.90  1.171.021.00Between Laboratory
135
0.820.690.66
0.890.770.74
1.531.431.41
1.901.811.79
The critical differences were calculated using t  = 1.96 which is based on infinite degrees of freedom.
Table III—Sample Crock Test Results
with Chromatic Scale
Dry
Wet Lab A    4.5  3.5Lab B    4.0  1.5Difference
0.5
2.0
Copyright © 2019 American Association of Textile Chemists and Colorists

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