Colorfastness to Crocking: AATCC Crockmeter Method
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 reaffirmed1968, 1974, 1977, 1981, 1995, 2001;editorially revised 1986, 2002. Partlyequivalent to ISO 105-X12.
1. Purpose and Scope
safe and proper techniques in handlingmaterials in this test method. Manufac-turers MUST be consulted for specificdetails such as material safety data sheetsand other manufacturer’s recommenda-tions. All OSHA standards and rulesmust also be consulted and followed.4.1 Good laboratory practices shouldbe followed. Wear safety glasses in alllaboratory areas.
5. Apparatus and Materials
1.1 This test method is designed to de-termine the amount of color transferredfrom the surface of colored textile materi-als to other surfaces by rubbing. It is ap-plicable to textiles made from all fibers inthe form of yarn or fabric whether dyed,printed or otherwise colored. It is not rec-ommended for use for carpets or forprints where the singling out of areas maybe too small using this method.
1.2 Test procedures employing whitetest cloth squares, both dry and wet withwater, are given.
1.3 As washing, drycleaning, shrink-age, ironing, finishing, etc., may affectthe degree of color transfer from a mate-rial, the test may be made before, after, orbefore and after any such treatment.
2. Principle
6. Verification
5.1 AATCC Crockmeter or comparablealternate apparatus (see 13.2, 13.3 andFig. 1).
5.2 Test Cloth, cut in 50 mm squares(see 13.4).
5.3 AATCC Chromatic TransferenceScale (see 13.5).
5.4 Gray Scale for Staining (see 13.5).5.5 White AATCC Textile BlottingPaper (see 13.5).
5.6 Specimen Holder for Crockmeter(see 13.3).
5.7 In-house poor crocking cloth.
5.8 Crockmeter Verification Cloth.This item may be used in lieu of an in-house poor crocking cloth when suchpoor in-house crocking cloth is not avail-able (see 13.15).
2.1 A colored test specimen is rubbedwith white crock test cloth under con-trolled conditions.
2.2 Color transferred to the white testcloth is assessed by a comparison withthe Gray Scale for Staining or the Chro-matic Transference Scale and a grade isassigned.
3. Terminology
3.1 colorfastness, n.—the resistance ofa material to change in any of its colorcharacteristics, to transfer of its color-ant(s) to adjacent materials, or both, as aresult of the exposure of the material toany 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 orfabric to another surface or to an adjacentarea of the same fabric principally byrubbing.
4. Safety Precautions
6.1 Verification checks on the opera-tion of the test and the apparatus shouldbe made routinely and the results kept ina log. The following observations andcorrective actions are extremely impor-tant to avoid incorrect test results whereabnormal crock images can result and in-fluence the rating process.
6.2 Use the Crockmeter VerificationCloth or in-house poor crocking fabric
with known behavior and conduct threedry 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 mayindicate a loose clip (see 13.6).
6.2.3 A stretched and streaked crockimage may be due to mounting the crocksquare diagonally.
6.2.4 Scuff marks to the sides of thespecimen indicate the loops to the wireclips are positioned downwards and arenot high enough to prevent rubbing thespecimen surface.
6.2.5 A streak in the center of the crockcloth image and in the direction of rub-bing may mean the top of the metal baseis warped and not flat. This will require abrace insert to square up the tester base.6.2.6 If specimen holders are used,place the holder over the specimen on thetester base. Move the crocking finger onthe 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 alltests. Without correction, this problemwill cause a dark area on one side of thecrocking image.
6.2.7 Confirm the wet pick-up tech-niques (see 9.2).
6.2.8 Replace the abrasive paper on thetester base if it is smooth to the touch inthe crocking area compared to the adja-cent area, or if slippage of the specimenis 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 longdimension oblique to the warp and fill-ing. If the direction of rubbing falls alonga twill line or surface pattern, etc., thenstreaks may occur. If they do occur,slightly adjust the angle for testing.
7. Test Specimens
NOTE: These safety precautions arefor 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
Fig. 1—Crockmeter.
7.1 Two specimens are used, one eachfor the dry and the wet tests.
7.1.1 Additional specimens may beused 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 towarp and filling or wales and courses.7.2.1 Larger or full width lab samplesmay be used without cutting individualspecimens, when multiple tests areneeded and when using for productiontesting.
AATCC Technical Manual/2008
Copyright © 2007 American Association of Textile Chemists and Colorists
TM 8-200717
7.3 Yarns. Knit a piece of fabric at least50 × 130 mm, or wind yarn tightly on asuitable form at least 50 × 130 mm withthe yarn running in the long direction; orotherwise stretched (see 13.8).
8. Conditioning
8.1 Prior to testing, precondition andcondition the test specimens and thecrock squares for crock testing as di-rected in ASTM D 1776, ConditioningTextiles for Testing. Condition each spec-imen for at least 4 h in an atmosphere of21 ± 1°C (70 ± 2°F) and 65 ± 2% RH bylaying each test specimen or crock squareseparately on a screen or perforated shelfof conditioning rack.
9. Procedures
9.1 Dry Crocking Test.
9.1.1 Place a test specimen on the baseof the Crockmeter resting flat on the abra-sive cloth with its long dimension in thedirection of rubbing (see 13.6 and 13.7).9.1.2 Place specimen holder over speci-men as an added means to preventslippage.
9.1.3 Mount a white test cloth square,the weave parallel with the direction ofrubbing, over the end of the finger whichprojects downward from the weightedsliding arm. Use the special spiral wireclip to hold the test square in place. Posi-tion the clip with loops upward. If theloops point downward they can dragagainst the test specimen.
9.1.4 Lower the covered finger onto thetest specimen. Beginning with the fingerpositioned at the front end, crank themeter handle 10 complete turns at the rateof one turn per second to slide the coveredfinger back and forth 20 times. Set andrun the motorized tester for 10 completeturns. Refer to individual specificationsfor any other required number of turns.9.1.5 Remove the white test clothsquare, condition (see 8.1) and evaluateas directed in Section 10. In the case ofnapped, brushed or sanded material whenloose fiber might interfere with the rating,remove the extraneous fibrous materialby pressing lightly on the crock circlewith the sticky side of cellophane tapebefore evaluating.
9.2 Wet Crocking Test.
9.2.1 Establish technique (see 13.10)for preparing wet crock cloth squares byweighing a conditioned square, then thor-oughly wet out white testing square indistilled water. Prepare only one square ata time.
9.2.2 Weigh dry crock square. Using asyringe tube, graduated pipette or auto-matic pipetter, draw up water in mL to0.65 times weight of crocking square. Ifcrocking 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 evenlyover crocking square and weigh the wetsquare. Calculate wet pickup accordingto instructions in AATCC Methods 8 and116, Colorfastness to Crocking test meth-ods. If needed, adjust the amount of waterused to wet the square and using a newcrocking square, repeat steps. When 65 ±5% wet pickup is achieved, record theamount of water used. Draw up the re-corded amount of water into the syringetube, graduated pipette or automatic pi-petter for each wet crocking performedduring the current day. Repeat this pro-cess each day.
9.2.3 Avoid evaporative reduction ofthe moisture content below the specifiedlevel 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, thencondition (see 8.1) before evaluating. Inthe case of napped, brushed or sandedmaterial when loose fiber might interferewith the rating, remove the extraneousfibrous material by pressing lightly on thecrock circle with the sticky side of cello-phane tape before evaluating.
10. Evaluation
Transference Scale.
Grade 2.5—color transfer equivalent toStep 2-3 on the Gray Scale for Staining orRow 2.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 2—color transfer equivalent toStep 2 on the Gray Scale for Staining orRow 2 on the 9-step AATCC ChromaticTransference Scale.
Grade 1.5—color transfer equivalent toStep 1-2 on the Gray Scale for Staining orRow 1.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 1—color transfer equivalent toStep 1 on the Gray Scale for Staining orRow 1 on the 9-step AATCC ChromaticTransference Scale.
10.4 Average individual results to thenearest 0.1 grade when multiple speci-mens are tested or when a panel of evalu-ators rate color transfer.
11. Report
10.1 Rate the amount of color trans-ferred from the specimen to the white testsquare under examination by means of theChromatic Transference Scale or the GrayScale for Staining (see 13.11 and 13.14).10.2 Back the test square with threelayers of white test cloth while evaluating.10.3 Rate dry and wet crocking fast-ness by means of the Gray Scale forStaining or the 9-step AATCC ChromaticTransference Scale. (Usage of thesescales is discussed in AATCC EvaluationProcedures 2, 3 and 8, respectively.)
Grade 5—negligible or no color transfer.Grade 4.5—color transfer equivalent toStep 4-5 on the Gray Scale for Staining orRow 4.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 4—color transfer equivalent toStep 4 on the Gray Scale for Staining orRow 4 on the 9-step AATCC ChromaticTransference Scale.
Grade 3.5—color transfer equivalent toStep 3-4 on the Gray Scale for Staining orRow 3.5 on the 9-step AATCC Chro-matic Transference Scale.
Grade 3—color transfer equivalent toStep 3 on the Gray Scale for Staining orRow 3 on the 9-step AATCC Chromatic
11.1 State whether dry or wet crockingtest.
11.2 Report the grade determined in 10.3.11.3 Report the grade determined in10.4 to the nearest 0.1 grade.
11.4 State whether Gray Scale forStaining or Chromatic TransferenceScale was used for evaluating staining(see 13.5, 13.9).
11.5 If any pretreatment or aftertreat-ment was given to any specimens (see1.3) indicate method of treatment.
12. Precision and Bias
12.1 Precision. An interlaboratory testwas conducted in 1986 to establish theprecision of the test method. Testing wasconducted under the normal atmosphericconditions of each laboratory and notnecessarily under ASTM standard condi-tions. Two operators at each of 12 labora-tories evaluated 5 fabrics in 3 replicationsby both dry and wet test method. Each of3 raters independently rated the stainedcrock squares using both the Gray Scalefor Staining and the Chromatic Transfer-ence Scale. The original data is on file atthe AATCC Technical Center.
12.1.1 The components of variance asstandard deviations of the Gray Scale forStaining or Chromatic TransferenceScale rating units are given in Table I.12.1.2 Critical differences are given inTable II.
Table I—Components of Variance
TestScale
Single Operator/RaterWithin LaboratoryBetween Laboratory
Dry
Chromatic0.200.200.10
Gray0.200.190.17
0.240.310.38
Wet
Chromatic
Gray0.250.340.54
18TM 8-2007
Copyright © 2007 American Association of Textile Chemists and Colorists
AATCC Technical Manual/2008
Table II—Critical Differences
For the components of variance in Table I, two averages of observed values should be consideredsignificantly different at the 95% probability level if the difference equals or exceeds the following criticaldifferences.TestScale
Single Operator/RaterWithin LaboratoryBetween Laboratory
No. ofObservations
135135135
Dry
Chromatic0.550.320.240.770.600.600.820.690.66
Gray0.540.310.240.750.610.570.890.770.74
0.680.390.301.080.930.901.531.431.41
Wet
Chromatic
Gray0.700.400.311.171.021.001.901.811.79
The critical differences were calculated using t = 1.96 which is based on infinite degrees of freedom.
Table III—Crock Test Results
Dry
Lab ALab BDifference
4.54.00.5
Wet3.51.52.0
Comparable apparatus, such as the Crock-master, both manual and motorized, isavailable from James H. Heal & Co. Ltd.,Richmond Works, Halifax HX3 6EP, Eng-land; tel: 44 1422 366355; fax: 44 1422352440; e-mail: info@james-heal.co.uk.
SDL Atlas L.L.C., 1813A Associate Lane,Charlotte NC 28217; tel: 704/329-0911; fax:704/329-0914; e-mail: info@sdlatlas.com.
12.1.3 Example for determining be-tween laboratory differences using oneobserver and the chromatic scale aregiven in Table III.
Interpretation: For the dry crock test,since the difference between labs is lessthan the critical differences in 12.1.2(0.82), the difference in results is not sig-nificant. For the wet crock test, since thedifference between labs is greater thanthe 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 interms 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—AATCCCrockmeter Method, under the jurisdiction ofCommittee RA57, Floor Covering Test Meth-ods, should be used.
13.2 The AATCC Crockmeter provides areciprocating rubbing motion simulating theaction 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, witheach complete turn of the crank, in a straightline along a 104 ± 3 mm track on the speci-men, with a downward force of 9 N ± 10%(2lb ± 10%). Two models, a manual andamotorized Crockmeter are available from
13.4 Crockmeter Test Cloth is availablefrom 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.com; or Textile Innovators Corp., div. ofSDL Atlas L.L.C., 3934 Airway Drive, RockHill SC 29732; tel: 803/329-2110; fax: 803/329-2133; e-mail: info@sdlatlas.com.
13.4.1 Crockmeter Test Cloth should meetthe following specifications:Fiber
100% 10.3-16.8 mm combedcotton staple, desized,bleached, with no opticalbrightener or finishing mate-rial present
Yarn15 tex (40/1 cotton count),
5.9 turns/cm “z”
Thread count32 ± 3 warp ends/cm: 33 ± 3
picks filling/cm
Weave1/1 plainpH7 ± 0.5
Mass/sq meter113 ± 5 g greige: 100 ± 3 g
finished
WhitenessW = 80 ± 2 (Method 110)13.5 The Chromatic Transference Scale,Gray Scales for Staining and White AATCCTextile Blotting Paper are available fromAATCC, P.O. Box 12215, Research TrianglePark NC 27709; tel: 919/549-8141; fax: 919/549-8933; e-mail: orders@aatcc.org.
13.6 Accidental damage to the rubbing fin-ger, spiral clip or abrasive paper should berepaired as follows: neatly renew the abrasivepaper; bend the clip further open or shutaround a rod slightly smaller in diameter thanthe 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 DryWaterproof Silicon Carbide, W-320-A, SoftBack.” Replacement pieces are available fromSDL Atlas L.L.C., 1813A Associate Lane,Charlotte NC 28217; tel: 704/329-0911; fax:704/329-0914; e-mail: info@sdlatlas.com.13.8 For more convenient crock testing ofmultiple strands of yarn or thread a dowel at-tachment is useful. This attachment was de-veloped to avoid the tendency of the standardfinger to dig into and push aside the yarns, orslide off them and possibly give erroneousresults. This attachment is 25 mm in diameterby 51 mm long. Positioned on its side and heldin place by the standard finger, it provides awider test area, and holds the white test squareby two spring loaded clips. For additional in-formation on this development see the articleby C. R. Trommer, “Modification of theAATCC Crockmeter for Yarn Testing,” Amer-ican Dyestuff Reporter, Vol. 45, No. 12, p357,June 4, 1956; also see articles by S. Korpantyand C. R. Trommer, “An Improved Crock-meter for Yarn Testing,” American DyestuffReporter, Vol. 48, No. 6, p40, March 23, 1959.A yarn testing finger kit for installation on theCrockmeter is available from SDL AtlasL.L.C., 1813A Associate Lane, Charlotte NC28217; tel: 704/329-0911; fax: 704/329-0914;e-mail: info@sdlatlas.com.
13.9 It has been noted that different gradesmay result depending upon whether theGrayScale for Staining or Chromatic Trans-ference Scale is used for the evaluation. It is,therefore, important to report which scale wasused.
13.10 Experienced operators do not have torepeat this weighing procedure during a testsession once the technique is established.
13.11 For very critical evaluations and incases of arbitration, grades must be based onthe Gray Scale for Staining.
13.12 For a discussion of crock testing, seethe article by J. Patton, “Crock Test Problemscan be Prevented,” Textile Chemist and Color-ist, Vol. 21, No. 3, p13, March 1989; and “Test-ing for Crocking: Some Problems and Pitfalls”by Allan E. Gore, Textile Chemists and Color-ists, Vol. 21, No. 3, p17, March 1989.
13.13 For prints where the singling out ofareas too small to test with the standardAATCC Crockmeter is necessary, see AATCCMethod 116, Rotary Vertical CrockmeterMethod. Specimens tested by both testmethods may show dissimilar results. Thereisno known correlation between the twomethods.
13.14 An automated electronic grading sys-tem may be used as long as the system hasbeen demonstrated to provide results that areequal to and provide equal or better repeatabil-ity and reproducibility than an experiencedgrader performing visual evaluation.
13.15 Crockmeter Verification Cloth isavailable from Textile Innovators Corp., div ofSDL Atlas L.L.C., 3934 Airway Drive, RockHill SC 29732; tel: 803/329-2110; fax: 803/329-2133; e-mail: info@sdlatlas.com. Detailson the performance of the current lot ofCrockmeter Verification Cloth are availablefrom the AATCC Technical Center.
AATCC Technical Manual/2008
Copyright © 2007 American Association of Textile Chemists and Colorists
TM 8-200719
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