Decoding AATCC TM 116: Colorfastness to crocking with ‘Rotary Vertical Crockmeter method

A critical property for textiles, colorfastness to crocking determines a fabric's resistance to color transfer when rubbed against another surface. To assess this property reliably, the American Association of Textile Chemists and Colorists (AATCC) developed Test Method 116: Colorfastness to Crocking: Rotary Vertical Crockmeter Method. This standardized procedure provides manufacturers, retailers, and quality control laboratories with a consistent method to evaluate a fabric’s tendency to transfer color during use.

Purpose and significance

AATCC Test Method 116 is designed to simulate conditions under which color transfer may occur in actual wear or use. Unlike linear or reciprocating crocking tests, this method employs a rotary vertical crockmeter, which allows for a circular rubbing motion. This rotary action more accurately reflects real-life rubbing conditions, such as when garments brush against furniture or when fabric layers rub together during movement.

This test method is vital to ensure dyed or printed fabrics maintain their appearance and do not stain other materials. Poor colorfastness to crocking can lead to consumer dissatisfaction, product returns, and damage to brand reputation. Hence, the test methodproves to be an essential tool in textile quality assurance programs.

Equipment and materials

The primary apparatus used in this test method is a rotary vertical crockmeter. The crockmeter consists of a rotating arm with a standard-size rubbing finger, typically covered with white test cloth made of standardized cotton. The finger rotates in a circular motion over the specimen, applying a consistent pressure—usually 11.1 ± 0.5 N (1.13 ± 0.05 kgf or 2.5 ± 0.1 lbf).

Test cloth squares (typically 50 x 50 mm) are attached to the rubbing finger. These cloths are inspected after the test to evaluate the amount of color transferred from the specimen. Both dry and wet crocking tests can be performed: for wet tests, the test cloth is moistened to a specified wet pickup (commonly 65 per cent).

Procedure

To perform this test, the fabric specimen is securely clamped onto the crockmeter’s specimen holder. A fresh piece of white crocking cloth is affixed to the rubbing finger. The crockmeter is then operated so that the finger rubs the specimen in a circular motion, usually completing 10

full rotations.

For wet tests, the crocking cloth is conditioned by wetting it with distilled water and squeezing it to the desired moisture content. After testing, the crocking cloth is removed and dried if necessary.

Evaluation

The degree of color transfer is assessed visually by comparing the tested crocking cloth against the AATCC Gray Scale for Staining or using an instrument for color measurement. The result is typically reported on a 1–5 scale, where 5 indicates no color transfer and 1 indicates heavy staining. Both dry and wet crocking results are reported separately, as wet crocking tends to cause more color transfer.

Applications

AATCC Test Method 116 is widely used across the textile industry, including apparel, upholstery, automotive textiles, and technical fabrics. It is especially important for deep or bright shades, pigment prints, and fabrics with surface treatments, where the risk of crocking is higher. Compliance with crocking standards helps manufacturers meet customer expectations, regulatory requirements, and retailer specifications.

The AATCC 116: Rotary Vertical Crockmeter Method is a critical test for evaluating the colorfastness to crocking of textiles. Its rotary motion provides a realistic simulation of everyday rubbing, making it a valuable tool for ensuring textile products perform as expected in the hands of consumers.