ISO 105-X12, C06, B02: Technical Specifications and In-depth Comparison of Textile Color Fastness

In the textile quality assessment system, color fastness is a decisive technical indicator for market access and consumer evaluation. This article provides an in-depth analysis of ISO 105-X12 (Color Fastness to Rubbing), ISO 105-C06 (Color Fastness to Washing), and ISO 105-B02 (Color Fastness to Light). By systematically examining physical wear, chemical thermal effects, and photodegradation mechanisms, we aim to help laboratories and manufacturers build a robust quality assurance system.

Core Knowledge: Technical Summary of Key Color Fastness Standards

To ensure precise testing, technical personnel must master the following three dimensions of core knowledge regarding the ISO 105 series:

• Physical Dimension (Rubbing): Rubbing fastness primarily depends on the physical state of the fiber surface, such as hairiness density, surface smoothness, and the adhesion of dye particles. Wet rubbing results are significantly influenced by the solubilizing and swelling effects of moisture on the dyes.
• Chemical Dimension (Washing): Washing fastness evaluates the chemical bonding strength (e.g., covalent bonds in reactive dyes) or intermolecular forces between dyes and fibers. Temperature, pH value, and mechanical impact during washing are the main factors accelerating color loss.
• Optical Dimension (Light): Light fastness depends on the photochemical stability of the dye molecules. High-energy ultraviolet rays induce redox reactions, leading to the breakage of chromophores. “Effective Humidity” within the environment is the most variable interference factor in light fastness testing.

In-depth Comparison: Technical Parameters of Rubbing, Washing, and Light Testing

The following table provides a horizontal comparison of core technical parameters, illustrating the fundamental differences between the three standards in simulating real-world usage scenarios:

Comparison Items	ISO 105-X12 (Rubbing)	ISO 105-C06 (Washing)	ISO 105-B02 (Light)
Evaluation Core	Physical wear and surface unfixed dye transfer	Color loss under wet-heat chemical conditions	Molecular stability under full-spectrum light
Key Equipment	Crockmeter	Rotational Washing Fastness Tester	Xenon Arc Weather-ometer
Core Parameters	Pressure 9 ± 0.1 N; Stroke 104 mm	Temperature 40°C – 95°C; Steel balls added	Black panel temp control; Effective humidity calibration
Grading Baseline	Grade 1-5 Gray Scale for Staining	Grade 1-5 Gray Scale for Color Change/Staining	Grade 1-8 standard Blue Wool References
Wet Treatment	95% – 100% moisture pick-up (distilled water)	ECE standard detergent + Sodium perborate	Controlling chamber humidity impact on references

ISO 105-X12 Rubbing Fastness: Assessing Physical Wear and Color Transfer in Daily Use

ISO 105-X12 color fastness to rubbing is a standardized protocol designed to quantify the risk of color transfer from textiles during everyday physical contact. The core logic involves simulating how unfixed “surface dye” particles transfer to a standard white cotton cloth under external pressure and friction. This test is conducted in both dry and wet states and is a critical indicator for evaluating whether denim, prints, and various dark-colored fabrics will “stain” surrounding items (such as light-colored sofas or clothing). The test results directly reflect the thoroughness of the post-dyeing soaping process and the resistance of finishing agents to physical peeling.

Equipment Specifications and Operating Parameters

To ensure global repeatability of results, ISO 105-X12 imposes strict mechanical requirements on the crockmeter:

• Downward Force: A constant vertical pressure of 9 ± 0.1 N is applied.
• Rubbing Track: The linear reciprocating stroke length is 104 ± 3 mm.
• Operating Frequency: 10 reciprocating cycles are completed uniformly within 10 seconds.
• Specimen Size: No less than 50 mm x 140 mm.

Grading Indicators and Commercial Application

Test results are evaluated using the ISO 105-A03 Gray Scale for Staining. Grade 5 represents no staining, while Grade 1 represents severe staining. In general trade, dry/wet rubbing for light-colored fabrics is usually required to be Grade 4 or higher; for dark-colored and reactive-dyed cotton fabrics, wet rubbing of Grade 2-3 is typically considered acceptable, while Grade 3 or higher is considered excellent. Failure to meet these standards often indicates insufficient reduction clearing after dyeing or that softeners have reduced the mechanical fastness of the dyes.

ISO 105-C06 Washing Fastness: Simulating Color Stability Under Domestic and Commercial Laundering

ISO 105-C06 color fastness to washing is a comprehensive testing protocol used to evaluate the ability of textiles to retain color and prevent staining in wet-heat chemical environments. By controlling temperature (40°C to 95°C), chemical additives (standard detergents and oxidants), and mechanical impact (steel balls), it simulates the entire process from gentle domestic washing to extreme commercial disinfection laundering. The core evaluation lies in the hydrolysis resistance of the dye-fiber bond. It serves as a vital barrier for preventing color fading or “cross-staining” in color-blocked garments (such as black-and-white striped shirts).

Test Programs and Common Sub-items (A1S – E2S)

ISO 105-C06 includes various sub-programs, with alphanumeric codes defining the severity of the wash:

• A2S (40°C): Simulates standard warm-water home laundering, typically adding 10 steel balls; suitable for most apparel.
• C2S (60°C): Simulates hot-water washing, adding 25 steel balls to increase mechanical force; often used for fabrics requiring high durability.
• E2S (95°C): Simulates extreme high-temperature commercial washing, primarily for hotel and medical linens.
• Note: The suffix “S” refers to a single wash simulation, while “M” refers to multiple wash simulations.

Grading Indicators: Color Change and Staining

The assessment consists of two parts: using the ISO 105-A02 Gray Scale to evaluate the fading degree of the specimen itself, and using the ISO 105-A03 Gray Scale to evaluate the staining on six different fiber types of the multi-fiber adjacent fabric. For adjacent fabrics containing nylon, low staining grades often suggest incomplete reduction clearing during the dyeing process, causing “thermal migration” of disperse dyes.

ISO 105-B02 Light Fastness: Assessing Resistance to Fading Under Full-Spectrum Artificial Light

ISO 105-B02 color fastness to light is a benchmark test that utilizes a xenon arc lamp to simulate natural sunlight radiation and evaluate the stability of dye molecules under photochemical action. Unlike physical rubbing or chemical washing, light fastness examines the resistance of dye chromophores to oxidative degradation after absorbing ultraviolet energy. This standard utilizes the unique “Blue Wool Reference” system and is the ultimate measure of environmental aging resistance for curtains, outdoor furniture, sun-shading equipment, and automotive interiors.

The 1-8 Blue Wool Scale System and Assessment

ISO 105-B02 does not use the 1-5 gray scale directly; instead, it uses standard blue wool reference samples ranging from Grade 1 to Grade 8:

1. Grades 1-3: Poor light fastness, suitable for indoor products not sensitive to light exposure.
2. Grades 4-5: Good level, a common entry-level indicator for most international apparel brands.
3. Grades 6-8: Excellent level, suitable for high-performance outdoor fabrics exposed to sunlight for long periods.

Critical Control Variable: Effective Humidity

Effective humidity is the variable most prone to deviation in light fastness testing. The standard strictly requires the daily use of a red cotton control fabric to calibrate the “Effective Humidity” inside the chamber, as it is restricted not only by environmental humidity but also by black panel temperature and airflow velocity. If effective humidity is too high, the fading rate of certain moisture-sensitive dyes (such as reactive dyes) will accelerate significantly, leading to incorrect low-grade results.

Common Misconceptions and Industry Precautions

• Misconception: If washing fastness is good, perspiration fastness must also be good. Truth: Acid/alkaline substances and amino acids in human sweat react chemically with dyes; washing tests cannot replace perspiration fastness assessments.
• Comparison Reminder: ISO 105-X12 requires 100% moisture pick-up for wet rubbing, while AATCC 8 requires only 65%. This means that samples passing under the ISO standard will typically perform better under the AATCC standard when exporting to the US market.
• Process Tip: Excessive heat-setting temperatures can cause dyes to “migrate” from the fiber interior to the surface, which simultaneously degrades both rubbing fastness and washing staining grades.

Summary

Textile color fastness is a comprehensive quality engineering task. Rubbing fastness (ISO 105-X12) relies on thorough cleaning of surface unfixed dyes and physical locking; Washing fastness (ISO 105-C06) depends on the stability of the dye-fiber bond and the reduction clearing process; and Light fastness (ISO 105-B02) is limited by the inherent anti-photo-oxidation capability of the dye molecules and the precise control of effective humidity in the test environment. By systematically mastering these three standards, manufacturers can not only avoid trade compliance risks but also enhance the final commercial value of their products through process optimization.

FAQ: Frequently Asked Questions on Color Fastness