AATCC 17-1999 Colorfastness to Crocking: Textile Floor Coverings— AATCC Crockmeter Method.
7. Verification
7.1 Verification checks on the operation 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 important to avoid incorrect test results where abnormal crock images can result and influence the rating process.
7.2 Use an in-house poor crocking carpet or rug as a calibration specimen and conduct three dry crock tests.
7.2.1 A double, elongated image may indicate a loose sleeve.
7.2.2 A stretched and streaked crock image may be due to mounting the crock test cloth diagonally.
7.2.3 Arc shaped indentions in the crocked area of the test cloth may indicate the crock block is mounted improperly, most likely perpendicular to the specified placement (see 13.2).
7.3 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.
8. Conditioning
8.1 Prior to testing, condition the test specimens and the crock test cloth for dry crock testing as directed in ASTM D 1776, Standard Practice for Conditioning and Testing Textiles. Condition each specimen for at least 4 h in an atmosphere of 21 ± 1°C and 65 ± 2% RH by laying each test specimen or crock test cloth 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 so that it rests flat on the abrasive cloth with its long dimension in the direction of rubbing (see 13.5). The pile lay should point to the back of the crockmeter if direction of pile is distin- guishable.
9.1.2 Mount a 25 × 100 mm swatch of white cotton test cloth over the rubbing surface of the crock block. The test cloth should be mounted so that the long dimension will be moving in the long direc- tion during the test. This operation can be carried out with the crock block attached to the weighted arm of the crockmeter using an Allen socket cap screw (see 13.6) or with the crock block detached from the arm and inverted in a suitable crock block holder (see 13.2 and 13.7). Fasten the test cloth to the crock block by means of a rectangular sleeve that slips over the cot- ton fabric on the crock block. AATCC 17 pdf download.