In the textile industry, colorfastness plays a crucial role. Colorfastness to crocking is one of the most common tests, performed in textile quality control laboratories. An instrument used for crocking is called a crockmeter. In this article, you will learn about crocking and crockmeter, and how to evaluate colorfastness to crocking systematically with the help of crockmeter.
What is Crocking?
The transfer of color from a textile material, which may be dyed or printed, onto the surface of another fabric through abrasion or rubbing is known as crocking. Let’s suppose a person is wearing a white cotton shirt and sits on a dyed or printed sofa set, which is covered by a dyed or printed seat cover. There is a possibility that the color from the sofa set could be transferred onto the person’s shirt. The color that transfers due to rubbing or abrasion is evaluated using a specific testing method called the crocking test, which is performed using equipment known as a crockmeter.
Types of Crocking
Dry crocking and wet crocking tests are performed on the dyed printed testing specimen. The dry crocking condition is the same for both AATCC & ISO, but the wet crocking conditions are different. According to AATCC standards, the wet pickup of the white crocking cloth should be 65 ± 5%, whereas according to ISO standard, it should be 100%. Sometimes, the testing specimen passes one type of crocking and fails the other. Failure of crocking test indicates the issues with the fixation of dyes or pigments or the surface treatment of the testing material.
Role of Crocking in Textile Industries
Crocking plays a vital role in textile industries. Suppose the color is transferring from the surface of textile materials or the garment to the skin or other clothing. In such cases, it can lead to customer dissatisfaction, product recalls, and legal implications.
In textile testing labs, the crocking test is essential for quality control during production and after finishing the textile material. It also facilitates raw material inspection, R&D for dyeing and finishing, and compliance with international standards. Each customer has their rating requirement. From a technical standpoint, and by customer protocols, a higher tolerance is allowed for wet crocking compared to dry conditions, as color transfer tends to be greater under wet conditions.
Crockmeter
The crockmeter is an instrument used in laboratory testing & quality control laboratories to assess crocking.
Types of Crockmeter
There are generally four types of crockmeters used in the textile quality control laboratories.
- The first type is a manual crockmeter, which is operated by hand and used for small-scale and basic testing, and this is the oldest instrument used to evaluate crocking fastness.
- The second type is a motorized crockmeter. A motor is installed in this type of crockmeters. It provides repeatable and consistent results, and it is suitable for large-scale testing.
- The third type of crockmeter is the rotary crockmeter. These are typically used for curved and non-flat surfaces, as well as printed textile materials.
- The fourth type of crockmeter is the AATCC crockmeter, which is specifically designed to meet all the requirements outlined in AATCC TM 08.
Darong offers the best crockmeters, suitable for all crocking or rubbing-related testing standards, including AATCC and ISO testing standards. I recommend visiting darongtester.com to choose a crockmeter that fits your specific requirements.
Crockmeter Testing Procedure
To evaluate colorfastness to crocking, the following items are required:
- Crockmeter: it may be manual or motorized, as per availability in the testing lab. I will recommend DaRong motorized crockmeter.
- Test specimen: The material you need to test may be dyed or printed.
- White test cloth: This cloth is a standard white cotton fabric used in textile labs worldwide.
- Deionized water: To moisten the white test cloth.
- Grey scale for staining to evaluate the color that transfers from dyed or printed fabric onto the white test fabric.
- Conditioning chamber: This chamber is required to get environmental conditions as per standard requirements. I will recommend the DaRong conditioning chamber, which can fulfill the requirements of all testing standards, including AATCC & ISO.
Standardized Test Methods
Below are some testing standards widely accepted in the textile industry. Please note that you will need to follow the testing standard as per the buyer’s requirements.
- AATCC TM-08
- ISO 105-X12
- GB/T 3920
- JIS L0849
AATCC TM-08 is colorfastness to crocking and AATCC crockmeter is required to perform this testing. ISO 105-X12 is referred to as colorfastness to rubbing, and you can use any crockmeter that meets all the requirements outlined in this testing procedure. GB/T 3920 is the testing method used in Chinese textile laboratories for colorfastness to crocking, while JIS L0849 is performed in Japan for colorfastness to rubbing.
White testing cloth for AATCC testing standardCrocking Test Procedure
First, we will discuss colorfastness to dry crocking.
Dry crocking / Rubbing
- Cut the testing specimen, which is conditioned in the DaRong conditioning chamber, and fix it on the platform of the crockmeter.
- Attach the white crocking test cloth to the rubbing finger of the crockmeter.
- Apply the required weight load, typically 9N.
- Start the machine to rub the testing specimen 10 times in a linear motion. (The motion can be circular if you are using a rotary crockmeter.
- After completing 10 cycles, remove the white test cloth and assess the degree of staining using a grey scale.
Wet crocking / Rubbing
- For AATCC wet croking, take a new white test fabric and moisten with distilled water till its weight increases by around 65 ± 5% of its dry weight.
- For ISO 105 X-12, take a new white test fabric and moisten it with distilled water till its weight increases by 100 % of its dry weight.
- Remove excess moisture, which exceeds testing requirements, with the help of blotting paper. (You can use a roller instead of blotting paper.)
- Repeat all steps from 1 to 5 of dry crocking.
Assessment of crocking/rubbing results
The stained white test cloth is compared against a grey scale for staining ISO 105-A03 or ATTCC EP-2, which ranges from grade 5 to grade 1. Grade 5 is the best result, meaning no stain, and Grade 1 is the worst result, meaning severe staining. Grade 4-5 or 4.5 is acceptable. Grade 3 is moderate and generally acceptable in dark shades or in innerwear. Grade 2 is a poor rating and fails in quality control. A point is to understand that wet crocking usually shows poorer results than dry crocking due to loosened dye or pigment molecules.
AssessmentFactors affecting rubbing results
- Fabric structure
Loosely woven textile articles shed dye more easily than tightly woven.
- Type of dye molecules
Different types of dyes exhibit varying behaviors when crocking, such as reactive dyes, which provide good wet fastness due to proper fixation. Direct dyes give poor wet crocking results ,while disperse dyes may cause staining in dry crocking.
- Dyeing process
The complete fixation of the dye molecule yields good crocking results, whereas incomplete fixation results in poor rubbing results. Washing after dyeing is essential to remove all unfixed dyes from the surface of the dyed article.
- Finishing chemicals:
Softeners and silicone coatings can control the transfer of dye molecules from the article. Some types of finishes may affect the test results if not completed properly.
- Test conditions:
Temperature and humidity more or less than the requirements can impact test results. The pressure on the rubbing finger, the number of cycles, and the quality of the testing cloth must be consistent.
Application of Crocking /Rubbing Across Industries
Rubbing tests are important in many textile sectors, such as:
- Fashion: In the fashion industry, a rubbing test is performed to ensure that dark garments will not stain lighter ones.
- Home Textiles: In home textiles, the crocking test helps avoid color transfer onto furniture or bedding.
- Automotive textiles: crocking helps to prevent seat fabrics from staining clothes.
Conclusion
Rubbing or crocking holds significance in the textile world. It indicates the amount of color that will transfer from the surface of a dyed or printed article to the surface of any other textile product. This test helps us to improve quality and leads to customer satisfaction. Dye bleeding has a significant impact on aquatic life, because dye bleeds, or repeatedly reprocess, rewash, or redye, it also increases the amount of wastewater and the chemicals from the wastewater enter the sea, which disturbs the aquatic life. Various instruments are available for test crocking. You can visit our website, darongtester.com, and select a machine according to your needs.
FAQs
What is a crockmeter?
Crockmeter is a testing instrument used to determine the color fastness of textile articles through rubbing (crocking). It can be manual or motorized and simulates repeated rubbing to evaluate dye stability.
What is crocking in textiles?
Crocking is the transfer of color from the surface of a dyed or printed fabric to the surface of another fabric by abrasion or crocking. This can occur when the dye has not properly adhered to the fibers.
What causes crocking?
Crocking is typically caused by:
- Inadequate dye fixation
- Use of low-quality dyes
- Improper washing or finishing processes
- Overdyeing or using excessive dye
What are dry and wet crocking?
- Dry Crocking: When a dry test cloth is rubbed or abraded against a fabric, the resulting color fastness is called dry crocking fastness.
- Wet Crocking: When a wet test cloth is rubbed or abraded against a fabric, the resulting color fastness is called wet crocking fastness.
How does a crockmeter work?
A piece of white test cloth is mounted on a rubbing finger that moves back and forth over a fixed fabric sample under a specific load and number of rubs. The crocking cloth is evaluated using the gray scale.
What are the standard test methods for crocking?
Common test standards include:
- AATCC 8 – is used specially for American customers
- ISO 105 X12 – is used for the rest of the world.
How is crocking test evaluated?
After rubbing, the test cloth is compared to a grayscale or staining scale (typically 1–5). The higher the number, the better the colorfastness.
Can the crockmeter be used for leather or prints?
Yes, crockmeters can test colorfastness of not only fabrics but also leather, prints, and coatings—provided appropriate testing procedures and materials are used.
Related Resources
Test Procedure of Rubbing Fastness Test Using JIS Standard Crockmeter
Crockmeter/Rubbing Colorfastness Tester