The Taber® Crockmeter - Model 418 provides a quick and accurate method to determine the amount of color transferred from textile materials (such as fabric, carpeting, yarn and leather) to other surfaces by rubbing. The Crockmeter has also been employed to perform rub abrasion, scuff and / or mar tests on flat specimens. Plus, it can be used to conduct smudge and smear resistance tests on images produced by a printer or copier. Regardless of specimen material, both wet and dry testing can be performed.
Description
Originally designed to simulate the action of a human finger and forearm, the Crockmeter uses a standard pressure and rubbing motion to provide reliable and reproducible test results. Specimens are positioned on the base of the Crockmeter and held in place with the sample holder. To prevent the specimen from shifting during testing, a sandpaper pad is provided to place under the specimen. A hand crank moves a reciprocating arm a distance of approximately 100mm. The rubbing action is provided by a 16mm diameter acrylic "finger" which moves back and forth in a straight line with each complete turn of the crank. The reciprocating load arm is weighted to provide a constant 9N load on the sample at all times and a mechanical counter keeps track of completed cycles.
Abradants
A standardized crocking cloth is most often used as the abradant for textile applications. This square (or sometimes circular) cloth is wrapped around the acrylic crock "finger" and held in place with a wire spring clip. AATCC Method 8 specifies the cloth should meet the following specifications:
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Fiber
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100% 10.3 - 16.8mm combed cotton staple, desized, bleached, with no optical brightener or finishing material present
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Yarn
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15 tex (40/1 cotton count), 5.09 turns/cm "z
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Thread Count
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32 +/-3 warp ends/cm: 33 +/-3 picks filling/cm
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Weave
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1/1 plain
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pH
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7 +/-0.5
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Mass/sq. meter
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113 +/-5g greige: 100 +/-3 g finished)
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Whiteness
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W = 80 +/-2
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Other abradants that might be used with the Crockmeter include felt, duck cloth, laboratory grade denim, coated abrasives (e.g. Polishing Paper, 281Q 3M WetorDry™), etc.