Evaluation of Color Fastness to Color Change: Grey Scale Methods, Standards, and Applications

Color fastness to color change evaluation measures a textile's resistance to visible color alteration caused by washing, rubbing, light exposure, perspiration, and other processing or end-use conditions. Using the grey scale rating system defined in ISO 105-A02, AATCC Evaluation Procedure 1, and GB/T 250, laboratories quantify color degradation from grade 5 (no change) to grade 1 (severe change). This article explains the technical principles, sample requirements, test items, assessment methods, and practical applications of color change evaluation in textile quality control.

Technical Overview

Color fastness to color change evaluation is a core procedure in textile testing that determines how much the color of a dyed or printed textile alters after exposure to a specified treatment such as laundering, rubbing, perspiration, water, light, or heat. In every color fastness test, two independent properties are assessed: the change in color of the specimen itself, and the staining transferred to an adjacent fabric. The evaluation of color change focuses exclusively on the degree of fading, dulling, or shade shift occurring on the original specimen.

The assessment is performed by comparing the tested specimen with an untreated original of the same material. The magnitude of difference is expressed as a grey scale rating in accordance with ISO 105-A02, AATCC Evaluation Procedure 1, EN ISO 105-A02, GB/T 250, and JIS L 0804. The grey scale for color change consists of nine pairs of grey chips, each pair comprising a reference chip and a test chip with a precisely controlled colorimetric difference expressed in CIELAB units.

• Grade 5: no visible change or negligible change (ΔE*ab approximately 0)
• Grade 4: slight change (ΔE*ab approximately 1.7)
• Grade 3: noticeable change (ΔE*ab approximately 3.4)
• Grade 2: considerable change (ΔE*ab approximately 6.8)
• Grade 1: severe change (ΔE*ab approximately 13.6)
• Intermediate half steps of 4-5, 3-4, 2-3, and 1-2 are used when the observed change falls between two whole grades

The main factors governing color change performance include dye class and depth of shade, fiber type and dye-fiber affinity, the completeness of after-washing and fixation during dyeing, and finishing treatments applied to the fabric. Because color change is one of the most common causes of consumer complaints and buyer rejections, it is a mandatory element of virtually all textile product specifications worldwide.

Testing Samples

Dyed and Printed Fabrics

Cut swatches are taken representative of the bulk fabric, away from the selvedge and from different positions across the width to account for dyeing irregularities. Typical dimensions include 40 mm × 100 mm specimens for washing and perspiration tests, and approximately 50 mm × 140 mm specimens for rubbing tests. Printed fabrics must be sampled so that every ground color and print color present on the design is represented.

Yarns and Loose Fibers

Yarn specimens are knitted into a suitable small swatch or wound tightly and uniformly onto a rigid board so that a flat, opaque test surface of uniform density is obtained. Loose fibers are combed and compressed into pads before testing. The original sample is retained in the same converted form as the tested specimen for comparison.

Garments and Made-Up Articles

Specimens are cut directly from the finished product, including all relevant components such as main fabric, collars, cuffs, linings, and trims. Each component is tested separately because different dye lots and fabric constructions frequently coexist within one garment. Labels, sewing threads, and coated accessories may also require evaluation where color loss is a concern.

Multicolored Specimens

When a specimen contains several colors, each distinct color area is assessed separately and reported individually, since a single fastness test can produce different levels of color change for different dyes on the same fabric. The lowest grade observed on any color area typically governs the acceptance decision for the article.

All specimens and their untreated originals must be conditioned in a standard atmosphere of 20 ± 2 °C and 65 ± 4% relative humidity in accordance with ISO 139 before final assessment, particularly when instrumental measurement is employed.

Testing Items

Color change evaluation is applied to every major color fastness property. The most frequently specified test items and their governing standards are listed below.

• Color fastness to domestic and commercial laundering — ISO 105-C06, AATCC 61, GB/T 3921
• Color fastness to rubbing (dry and wet crocking) — ISO 105-X12, AATCC 8, GB/T 3920
• Color fastness to artificial light (xenon arc) — ISO 105-B02, AATCC 16, GB/T 8427
• Color fastness to acid and alkaline perspiration — ISO 105-E04, AATCC 15, GB/T 3922
• Color fastness to water — ISO 105-E01, AATCC 107, GB/T 5713
• Color fastness to seawater — ISO 105-E02, GB/T 5714
• Color fastness to chlorinated pool water — ISO 105-E03
• Color fastness to dry cleaning — ISO 105-D01, GB/T 5711
• Color fastness to hot pressing and ironing — ISO 105-X11, GB/T 6152
• Color fastness to dry heat (sublimation) — ISO 105-P01, GB/T 5718
• Color fastness to ozone in the atmosphere — ISO 105-G03
• Color fastness to hypochlorite and non-chlorine bleach — ISO 105-N01/N02

For each item, the property is reported as the grey scale rating for color change of the specimen, usually alongside the staining rating of the adjacent fabric assessed with the staining scale of ISO 105-A03 or AATCC Evaluation Procedure 2.

Testing Methods

Visual Grey Scale Assessment

Visual assessment is performed in a color assessment cabinet under D65 illumination at an illuminance of at least 600 lux, with the light incident at approximately 45° and the assessor viewing the specimen perpendicularly or at 45° from a distance of roughly 30 to 40 cm. The original and treated specimens are placed side by side, in the same orientation and surface direction, adjacent to the grey scale against a neutral grey background mask. The assessor, who must have verified normal color vision, selects the grey pair whose apparent contrast matches the contrast between the original and tested specimen, and assigns the corresponding grade.

Instrumental Assessment

Instrumental evaluation eliminates subjectivity by measuring the CIELAB coordinates of the original and tested specimens with a calibrated spectrophotometer, typically under D65 illuminant and 10° standard observer conditions. The color difference ΔE*ab is calculated and converted into a grey scale rating using the mathematical procedure defined in ISO 105-A05, AATCC Evaluation Procedure 7, and the equivalent GB/T methodology. Instrumental results are widely accepted by retailers and are particularly valuable for resolving disputes between visual ratings.

Assessment Procedure After Testing

After the specified treatment, specimens are rinsed or dried according to the test method, then brushed lightly if necessary to restore the original surface configuration without altering the color. Specimens must not be trimmed, pressed, or otherwise reconditioned in a way that would mask or exaggerate the color change. Assessment takes place after the specimen has returned to standard atmospheric conditions.

Reporting

A complete test report states the test method and severity conditions, the grey scale rating for color change of every color area, the ratings for staining where applicable, the assessment mode (visual or instrumental), the illuminant used, and any deviations from the standard procedure. Half-step grades are recorded when the observed change lies between two whole grades.

Applications

Color change evaluation underpins quality control, regulatory compliance, and commercial acceptance throughout the textile supply chain.

• Apparel manufacturing: verifying that fabrics and garments meet buyer specifications, typically requiring grade 4 or higher for washing, rubbing, and perspiration, with grade 3-4 sometimes accepted for deep shades
• Regulatory compliance: meeting mandatory minimum fastness levels in national safety standards such as GB 18401, which requires grade 3 or above for most categories and higher grades for infant products
• Home textiles: ensuring bedding, towels, and curtains retain shade after repeated domestic laundering and light exposure
• Automotive textiles: qualifying interior trim materials against severe light and heat fastness requirements specified by vehicle manufacturers
• Uniforms and workwear: confirming color durability under industrial laundering and prolonged UV exposure
• Fabric development and failure analysis: comparing dyes, auxiliaries, and dyeing recipes during product development and diagnosing the cause of field complaints
• Certification programs: generating the fastness data required for eco-labels and product certification schemes that rely on testing by accredited third-party laboratories

FAQ

What is the difference between color change and staining evaluation?

Color change assessment measures the degree of fading or shade shift on the tested specimen itself using the grey scale of ISO 105-A02. Staining assessment measures the color transferred to an adjacent white fabric using the staining scale of ISO 105-A03. Both are reported for most fastness tests, but they evaluate two different failure modes.

What grey scale rating is considered acceptable?

For most commercial products, grade 4 or higher for color change is the general expectation for washing, perspiration, water, and rubbing. Many specifications allow grade 3-4 for very dark or brilliant shades. Regulatory minimums such as those in GB 18401 typically require grade 3 as the lowest limit for general products and grade 4 for infant articles.

Can grey scale ratings be determined instrumentally?

Yes. ISO 105-A05 and AATCC Evaluation Procedure 7 define a conversion of the measured CIELAB color difference into grey scale ratings, producing objective and reproducible results. Instrumental assessment is increasingly preferred for arbitration and for internal quality control in accredited third-party laboratories.

Why do visual ratings sometimes differ between laboratories?

Differences can arise from non-standard illuminance, an incorrect light source, assessor color vision variation, surface distortion of the specimen, or inconsistent specimen orientation. Using a D65 color assessment cabinet, trained assessors, and defined viewing geometry minimizes disagreement, and instrumental verification can be used to resolve disputes.

How are multicolored or printed fabrics rated?

Every distinct color area on the specimen is assessed separately, and each result is reported individually. The governing grade for acceptance is generally the lowest rating recorded on any color area of the specimen.

Does light fastness use the same grey scale?

No. Light fastness is normally rated from 1 to 8 by comparison with blue wool reference standards under ISO 105-B02, although the grey scale for color change may be used as a supplementary criterion. The 1 to 5 grey scale applies to the other fastness properties such as washing, rubbing, and perspiration.