Color Fastness

Types of Color Fastness:

1. Light Fastness

Light fastness is the resistance of textile color to fading when exposed to light, especially sunlight or artificial light.

Cause of Color Fading

• UV radiation breaks down dye molecules
• Oxidation reactions
• Poor dye–fiber bonding

Testing Method

• Tested using Blue Wool Scale
• Exposed to artificial light in a light fastness tester
• Compared with standard blue wool references

Grading Scale (1–8)

• Fashion garments: ≥ 4
• Outdoor/workwear: ≥ 6
• Curtains/upholstery: ≥ 7

2. Washing Fastness

Washing fastness measures resistance of color to fading and staining during laundering.

What It Evaluates

• Color change of the dyed fabric
• Color staining on adjacent fabrics (cotton, polyester, nylon, wool, acrylic)

Testing Method

• ISO 105‑C series / AATCC 61
• Fabric washed under controlled temperature, detergent, time and agitation

Grading Scale (1–5)

Typical Buyer Requirement

• Color change: ≥ 4
• Staining: ≥ 3–4

3. Abrasion Fastness (Rub Fastness)

Abrasion (rubbing) fastness is the resistance of a dyed fabric to color transfer when rubbed against another surface.

Types

• Dry rubbing fastness
• Wet rubbing fastness (more critical)

Testing Method

• ISO 105‑X12 / AATCC 8
• Tested using a crockmeter

Grading Scale (1–5)

• 5 = No color transfer
• 1 = Heavy color transfer

Common Issues

• Dark shades (black, navy, red)
• Pigment dyeing
• Incomplete wash‑off in reactive dyeing

Typical Requirements

• Dry rubbing: ≥ 4
• Wet rubbing: ≥ 3

4. Perspiration (Saliva) Fastness

Perspiration fastness measures resistance of color to human sweat, which may be acidic or alkaline.

Saliva fastness is especially important for:

• Baby garments
• Infant accessories
• Toys and textiles that may be mouthed

Testing Method

• ISO 105‑E04 / AATCC 15
• Fabric exposed to artificial sweat solution
• Pressure and heat applied

Types of Perspiration

• Acid perspiration (pH ≈ 5.5)
• Alkaline perspiration (pH ≈ 8)

Grading Scale (1–5)

• Color change
• Staining on adjacent fabric

Typical Requirement

• ≥ 4 for both color change and staining

5. Factors Affecting Color Fastness

Dye‑Related Factors

• Dye class (reactive, disperse, vat, pigment, etc.)
• Molecular size and structure
• Dye purity

Fiber‑Related Factors

• Fiber type (cotton, polyester, nylon, wool)
• Surface morphology
• Crystallinity

Process‑Related Factors

• Dyeing temperature and time
• pH control
• Salt and alkali dosage
• Washing‑off and soaping quality

Finishing Factors

• Softener type
• Resin finishes
• Heat setting

6. Improving Color Fastness

• Select correct dye class for fiber type
• Follow proper dyeing curves
• Ensure complete dye fixation
• Perform thorough wash‑off and soaping
• Use fixing agents where applicable
• Control pH and temperature
• Avoid over‑application of softeners

7. Common Dyeing Problems Related to Poor Fastness

8. Buyer & Compliance Importance

Most global buyers require:

• ISO / AATCC standard testing
• Minimum fastness grades defined in tech packs
• Compliance with RSL and ZDHC MRSL
• Special limits for babywear and skin‑contact garments

Color Fastness & Appearance Scales Used in Textile Dyeing

Textile quality evaluation relies on standard visual and instrumental scales to ensure global consistency between laboratories, suppliers and buyers. These scales help judge color change, staining, fading, pilling, abrasion and whiteness.

1. Grey Scale 

The Grey Scale is a set of standardized grey color chips used to assess:

1. Color Change of the dyed fabric
2. Color Staining on adjacent (undeyed) fabric

It is used when comparing before‑and‑after samples in most fastness tests.

Scale:

• 1 to 5
  (5 = Excellent, 1 = Very Poor)

Grey Scale Rating System

Grey Scale uses a 1 to 5 grading system:

Grade	Meaning
5	No change / No staining
4–5	Slight change
4	Small change
3–4	Noticeable change
3	Moderate change
2	Significant change
1	Severe change / Heavy staining

Standards:

• ISO 105‑A02 (Color Change)
• ISO 105‑A03 (Staining)

2. Blue Scale 

The Blue Scale is a set of eight blue‑dyed wool strips used to assess light fastness of textiles.

Unlike grey scale, the blue scale does not compare two fabric samples. Instead, it compares the degree of fading of a test specimen against standardized blue references.

Scale:

• 1 to 8
  (8 = Outstanding, 1 = Very Poor)

Grade	Meaning
8	Outstanding light fastness
7	Excellent
6	Very good
5	Good
4	Moderate
3	Fair
2	Poor
1	Very poor

Standards:

• ISO 105‑B02
• AATCC 16

3. AATCC Chromatic Transference Scale

An alternative to Grey Scale for staining, used mainly in AATCC test methods.

Scale:

• 1 to 5
• Evaluates color transfer to adjacent fabric

Where Used:

• AATCC 61 (washing)
• AATCC 8 (crocking)
• AATCC 15 (perspiration)

Difference from Grey Scale:

• More chromatic‑based rather than neutral grey
• Still visually assessed

4. Pilling Rating Scale

Used to evaluate surface fuzzing and pilling caused by abrasion during wear and washing.

Scale:

• 5 = No pilling
• 1 = Severe pilling

Test Methods:

• ISO 12945‑1 (ICI Pilling Box)
• ISO 12945‑2 (Martindale)
• ASTM D4970
• ASTM D3512 (Random Tumble)

Common Use:

• Knit fabrics
• Fleece
• Brushed fabrics
• Sweaters

5. Martindale Abrasion Scale

Used to measure abrasion resistance, not color transfer.

Output:

• Number of cycles to breakdown or appearance change

Typical Ratings:

• Light apparel: 5,000–10,000 cycles
• Heavy duty: 20,000–50,000+ cycles

Standard:

• ISO 12947

6. Crocking (Rubbing) Scale

Used for:

• Dry and wet rubbing fastness

Scale:

• 1 to 5

Standards:

• ISO 105‑X12
• AATCC 8

Notes:

• Wet crocking is usually 1 grade lower than dry
• Dark shades are more critical

7. Whiteness Index Scale

Measures how white a fabric appears after bleaching or optical brightening.

Scale Type:

• Instrumental, not visual
• Numerical value (e.g. CIE Whiteness Index)

Standards:

• ISO 105‑J02
• ASTM E313

Used for:

• White garments
• Towels
• Medical textiles

8. Yellowness Index

Measures yellowing caused by:

• Heat
• Aging
• Improper bleaching
• Resin finishes

Scale:

• Instrumental numerical value

Standard:

• ASTM E313

9. Color Difference Scale (ΔE)

An instrument‑based color scale that quantifies shade difference between:

• Lab dip vs standard
• Bulk vs approved shade

Common Systems:

• ΔE*ab (CIELAB)
• ΔE CMC (l:c)
• ΔE 2000

Typical Acceptance:

• ΔE ≤ 1.0–1.5 (buyer dependent)

10. Perspiration / Saliva Fastness Scale

Used for:

• Human sweat
• Baby garments and toys

Scale:

• 1 to 5 (Grey Scale or Chromatic Scale)

Standards:

• ISO 105‑E04
• DIN 53160 (saliva)

11. Sublimation Fastness Scale

Measures resistance to color change and transfer under heat.

Scale:

• 1 to 5

Used for:

• Polyester
• Heat‑transfer printing
• Ironing resistance

Standards:

• ISO 105‑P01
• AATCC 117

12. Weathering / Outdoor Exposure Scale

Evaluates combined effects of:

• Light
• Heat
• Moisture

Scale:

• Often expressed using Blue Scale
• Or appearance change rating

Standards:

• ISO 105‑B04
• AATCC 169

Typical Light Fastness Requirements

End Use	Minimum Blue Scale Grade
Fashion garments	≥ 4
Sportswear	≥ 4–5
Workwear	≥ 5–6
Curtains	≥ 6
Outdoor textiles	≥ 7

Summary Table (Quick Reference)

Scale Name	Rating Range	Used For
Grey Scale	1–5	Color change & staining
Blue Scale	1–8	Light fastness
Chromatic Transference	1–5	Staining (AATCC)
Pilling Scale	1–5	Surface pilling
Crocking Scale	1–5	Rubbing fastness
Martindale Cycles	Numeric	Abrasion resistance
Whiteness Index	Numeric	Fabric whiteness
Yellowness Index	Numeric	Yellowing
ΔE Scale	Numeric	Shade difference
Sublimation Scale	1–5	Heat fastness
Weathering Scale	1–8 / Visual	Outdoor durability