Copyright © 2007 American Association of Textile Chemists and Colorists
AATCC Technical Manual/2008
TM 8-200717
Developed in 1936 by AATCC Commit-tee RA38; revised 1937, 1952, 1957,1961, 1969, 1972, 1985, 1988, 1996,2004, 2005, 2007; reaffirmed 1945;1989; editorially revised and reaffirmed 1968, 1974, 1977, 1981, 1995, 2001;editorially revised 1986, 2002. Partly equivalent to ISO 105-X12.
1. Purpose and Scope
1.1 This test method is designed to de-termine the amount of color transferred from the surface of colored textile materi-als to other surfaces by rubbing. It is ap-plicable to textiles made from all fibers in the form of yarn or fabric whether dyed,printed or otherwise colored. It is not rec-ommended for use for carpets or for prints where the singling out of areas may be too small using this method.
1.2 Test procedures employing white test cloth squares, both dry and wet with water, are given.
1.3 As washing, drycleaning, shrink-age, ironing, finishing, etc., may affect the degree of color transfer from a mate-rial, the test may be made before, after, or before and after any such treatment.
2. Principle
2.1 A colored test specimen is rubbed with white crock test cloth under con-trolled conditions.
2.2 Color transferred to the white test cloth is assessed by a comparison with the Gray Scale for Staining or the Chro-matic Transference Scale 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. Apparatus and Materials
5.1 AATCC Crockmeter or comparable alternate apparatus (see 13.2, 13.3 and Fig. 1).
5.2 Test Cloth, cut in 50 mm squares (see 13.4).
5.3 AATCC Chromatic Transference Scale (see 13.5).
5.4 Gray Scale for Staining (see 13.5).5.5 White AATCC Textile Blotting Paper (see 13.5).
5.6 Specimen Holder for Crockmeter (see 13.3).
5.7 In-house poor crocking cloth.
5.8 Crockmeter V erification Cloth.This item may be used in lieu of an in-house poor crocking cloth when such poor in-house crocking cloth is not avail-able (see 13.15).
6. Verification
6.1 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.
6.2 Use the Crockmeter Verification Cloth or in-house poor crocking fabric
with known behavior and conduct three dry and wet crock tests.
6.2.1 A poor circular image with un-even dye pick-up may indicate the crock-ing finger needs resurfacing (see 13.6).6.2.2 A double, elongated image may indicate a loose clip (see 13.6).
6.2.3 A stretched and streaked crock image may be due to mounting the crock square diagonally.
6.2.4 Scuff marks to the sides of the specimen indicate the loops to the wire clips are positioned downwards and are not high enough to prevent rubbing the specimen surface.
6.2.5 A streak in the center of the crock cloth image and in the direction of rub-bing may mean the top of the metal base is warped and not flat. This will require a brace insert to square up the tester base.6.
2.6 If specimen holders are used,place the holder over the specimen on the tester base. Move the crocking finger on the crocking arm to the most forward po-sition and observe whether it hits the in-side edge of the holder. If this occurs,move the holder slightly forward for all tests. Without correction, this problem will cause a dark area on one side of the crocking image.
6.2.7 Confirm the wet pick-up tech-niques (see 9.2).
6.2.8 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, or if slippage of the specimen is noticed (see 13.7).
6.2.9 In routine testing, observe if mul-tiple streaks are on the crocking image.Position specimen normally 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.
7. Test Specimens
7.1 Two specimens are used, one each for the dry and the wet tests.
7.1.1 Additional specimens may be used to increase the precision of the aver-age (see 12.1).
7.2 Cut specimens at least 50 × 130 mm (2.0 × 5.1 in.) and position for testing pref-erably with the long dimension oblique to warp and filling or wales and courses.7.2.1 Larger or full width lab samples may be used without cutting individual specimens, when multiple tests are needed and when using for production testing.
AATCC Test Method 8-2007
Colorfastness to Crocking: AATCC Crockmeter Method
Fig. 1—Crockmeter.
Copyright © 2007 American Association of Textile Chemists and Colorists
18TM 8-2007
AATCC Technical Manual/2008
7.3 Yarns. Knit a piece of fabric at least 50 × 130 mm, or wind yarn tightly on a suitable form at least 50 × 130 mm with the yarn running in the long direction; or otherwise stretched (see 13.8).
8. Conditioning
8.1 Prior to testing, precondition and condition the test specimens and the crock squares for crock testing as di-rected in ASTM D 1776, Conditioning Textiles for Testing. Condition each spec-imen for at least 4 h in an atmosphere of 21 ± 1°C (70 ± 2°F) and 65 ± 2% RH by laying each test specimen or crock square separately on a screen or perforated shelf of conditioning rack.
9. Procedures
9.1 Dry Crocking Test.
9.1.1 Place a test specimen on the base of the Crockmeter resting flat on the abra-sive cloth with its long dimension in the direction of rubbing (see 13.6 and 13.7).9.1.2 Place specimen holder over speci-men as an added means to prevent slippage.
9.1.3 Mount a white test cloth square,the weave parallel with the direction of rubbing, over the end of the finger which projects downward from the weighted sliding arm. Use the special spiral wire clip to hold the test square in place. Posi-tion the clip with loops upward. If the loops point downward they can drag against the test specimen.
9.1.4 Lower the covered finger onto the test specimen. Beginning with the finger positioned at the front end, crank the meter handle 10 complete turns at the rate of one turn per second to slide the covered finger back and forth 20 times. Set and run the motorized tester for 10 complete turns. Refer to individual specifications for any other required number of turns.9.1.5 Remove the white test cloth square, condition (see 8.1) and evaluate as directed in Section 10. 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.
9.2 Wet Crocking Test.
9.2.1 Establish technique (see 13.10)for preparing wet crock cloth squares by weighing a conditioned square, then thor-oughly wet out white testing square in distilled water. Prepare only one square at a time.
9.2.2 Weigh dry crock square. Using a syringe tube, graduated pipette or auto-matic pipetter, draw up water in mL to 0.65 times weight of crocking square. If crocking square weight equals 0.24 gm,the mL used would be 0.24 × 0.65 = 0.16mL. Lay crocking square on white plastic
mesh over a dish. Apply water evenly over crocking square and weigh the wet square. Calculate wet pickup according to instructions in AATCC Methods 8 and 116, Colorfastness to Crocking test meth-ods. If needed, adjust the amount of water used to wet the square and using a new crocking square, repeat steps. When 65 ±5% wet pickup is achieved, record the amount of water used. Draw up the re-corded amount of water into the syringe tube, graduated pipette or automatic pi-petter for each wet crocking performed during the current day. Repeat this pro-cess each day.
9.2.3 Avoid evaporative reduction of the moisture content below the specified level before the actual crock test is run.9.2.4 Continue as directed in 9.1.
9.2.5 Air dry the white test square, then condition (see 8.1) before evaluating. 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 cello-phane tape before evaluating.
10. Evaluation
10.1 Rate the amount of color trans-ferred from the specimen to the white test square under examination by means of the Chromatic Transference Scale or the Gray Scale for Staining (see 13.11 and 13.14).10.2 Back the test square with three layers of white test cloth while evaluating.10.3 Rate dry and wet crocking fast-ness by means of the Gray Scale for Staining or the 9-step AATCC Chromatic Transference Scale. (Usage of these scales is discussed in AATCC Evaluation Procedures 2, 3 and 8, respectively.)
Grade 5—negligible or no color transfer.Grade 4.5—color transfer equivalent to Step 4-5 on the Gray Scale for Staining or Row 4.5 on the 9-step AA TCC Chro-matic Transference Scale.
Grade 4—color transfer equivalent to Step 4 on the Gray Scale for Staining or Row 4 on the 9-step AATCC Chromatic Transference Scale.
Grade 3.5—color transfer equivalent to Step 3-4 on the Gray Scale for Staining or Row 3.5 on the 9-step AA TCC Chro-matic Transference Scale.
Grade 3—color transfer equivalent to Step 3 on the Gray Scale for Staining or Row 3 on the 9-step AATCC Chromatic
Transference Scale.
Grade 2.5—color transfer equivalent to Step 2-3 on the Gray Scale for Staining or Row 2.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 2—color transfer equivalent to Step 2 on the Gray Scale for Staining or Row 2 on the 9-step AATCC Chromatic Transference Scale.
Grade 1.5—color transfer equivalent to Step 1-2 on the Gray Scale for Staining or Row 1.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 1—color transfer equivalent to Step 1 on the Gray Scale for Staining or Row 1 on the 9-step AATCC Chromatic Transference Scale.
10.4 Average individual results to the nearest 0.1 grade when multiple speci-mens are tested or when a panel of evalu-ators rate color transfer.
11. Report
11.1 State whether dry or wet crocking test.
11.2 Report the grade determined in 10.3.11.3 Report the grade determined in 10.4 to the nearest 0.1 grade.
11.4 State whether Gray Scale for Staining or Chromatic Transference Scale was used for evaluating staining (see 13.5, 13.9).
11.5 If any pretreatment or aftertreat-ment was given to any specimens (see 1.3) indicate method of treatment.
12. Precision and Bias
12.1 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 standard condi-tions. Two operators at each of 12 labora-tories evaluated 5 fabrics in 3 replications by both dry and wet test method. Each of 3 raters independently rated the stained crock squares using both the Gray Scale for Staining and the Chromatic Transfer-ence Scale. The original data is on file at the AATCC Technical Center.
12.1.1 The components of variance as standard deviations of the Gray Scale for Staining or Chromatic Transference Scale rating units are given in Table I.12.1.2 Critical differences are given in Table II.
Table I—Components of Variance
Test Scale
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
Copyright © 2007 American Association of Textile Chemists and Colorists
AATCC Technical Manual/2008
TM 8-200719
12.1.3 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 differences in 12.1.2(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.
12.2 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.
13. Notes
13.1 For carpets, AATCC Method 165, Col-orfastness to Crocking: Carpets—AATCC Crockmeter Method, under the jurisdiction of Committee RA57, Floor Covering Test Meth-ods, should be used.
13.2 The AATCC Crockmeter provides a reciprocating rubbing motion simulating the action of a human finger and forearm.
13.3 The AATCC Crockmeter is so de-signed that the 16 ± 0.3 mm (0.625 ± 0.01 in.)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 speci-men, with a downward force of 9 N ± 10%(2lb ± 10%). Two models, a manual and a motorized Crockmeter are available from
SDL Atlas L.L.C., 1813A Associate Lane,Charlotte NC 28217; tel: 704/329-0911; fax:704/329-0914; e-mail: info@sdlatlas.
Comparable apparatus, such as the Crock-master, both manual and motorized, is available from James H. Heal & Co. Ltd.,Richmond Works, Halifax HX3 6EP, Eng-land; tel: 44 1422 366355; fax: 44 1422352440; e-mail: uk.
13.4 Crockmeter Test Cloth is available from Testfabrics Inc., P.O. Box 26, 415 Dela-ware St., W. Pittston PA 18643; tel: 570/603-0432; fax: 570/603-0433; e-mail: testfabric@aol; or Textile Innovators Corp., div. of SDL Atlas L.L.C., 3934 Airway Drive, Rock Hill SC 29732; tel: 803/329-2110; fax: 803/329-2133; e-mail: info@sdlatlas.
13.4.1 Crockmeter Test Cloth should meet the following specifications:Fiber
100% 10.3-16.8 mm combed cotton staple, desized,bleached, with no optical brightener or finishing mate-rial present
Yarn 15 tex (40/1 cotton count),
5.9 turns/cm “z”
Thread count 32 ± 3 warp ends/cm: 33 ± 3
editoriallypicks filling/cm
Weave 1/1 plain pH 7 ± 0.5
Mass/sq meter 113 ± 5 g greige: 100 ± 3 g
finished
Whiteness W = 80 ± 2 (Method 110)13.5 The Chromatic Transference Scale,Gray Scales for Staining and White AATCC Textile Blotting Paper are available from AATCC, P.O. Box 12215, Research Triangl
e Park NC 27709; tel: 919/549-8141; fax: 919/549-8933; e-mail:
13.6 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.
13.7 The abrasive material currently sup-plied with the Crockmeter is “Wet or Dry Waterproof Silicon Carbide, W-320-A, Soft Back.” Replacement pieces are available from SDL Atlas L.L.C., 1813A Associate Lane,Charlotte NC 28217; tel: 704/329-0911; fax:704/329-0914; e-mail: info@sdlatlas.13.8 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,” Amer-ican Dyestuff Reporter , V ol. 45, No. 12, p357,June 4, 1956; also see articles by S. Korpanty and C. R. Trommer, “An Improved Crock-meter for Yarn Testing,” American Dyestuff Reporter , V ol. 48, No. 6, p40, March 23, 1959.A yarn testing finger kit for installation on the Crockmeter is available from SDL Atlas L.L.C., 1813A Associate Lane, Charlotte NC 28217; tel: 704/329-0911; fax: 704/329-0914;e-mail: info@sdlatlas.
13.9 It has been noted that different grades may result depending upon whether the Gray Scale for Staining or Chromatic Trans-ference Scale is used for the evaluation. It is,therefore, important to report which scale was used.
13.10 Experienced operators do not have to repeat this weighing procedure during a test session once the technique is established.
13.11 For very critical evaluations and in cases of arbitration, grades must be based on the Gray Scale for Staining.
13.12 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, p13, March 1989; and “Test-ing for Crocking: Some Problems and Pitfalls”by Allan E. Gore, Textile Chemists and Color-ists , V ol. 21, No.
3, p17, March 1989.
13.13 For prints where the singling out of areas too small to test with the standard AATCC Crockmeter is necessary, see AATCC Method 116, Rotary Vertical Crockmeter Method. Specimens tested by both test methods may show dissimilar results. There is no known correlation between the two methods.
13.14 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.
13.15 Crockmeter Verification Cloth is available from Textile Innovators Corp., div of SDL Atlas L.L.C., 3934 Airway Drive, Rock Hill SC 29732; tel: 803/329-2110; fax: 803/329-2133; e-mail: info@sdlatlas. Details on the performance of the current lot of Crockmeter Verification Cloth are available from the AATCC Technical Center.
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.Test Scale
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—Crock Test Results
Dry
Wet Lab A 4.5 3.5Lab B 4.0 1.5Difference
0.5
2.0
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