Color Fastness Evaluation of Printed Materials: Standards, Methods, and Applications

Color fastness evaluation determines how well printed colors on paper, paperboard, plastic film, and other substrates resist fading, bleeding, and transfer when exposed to rubbing, light, moisture, heat, and chemical agents. This technical article explains the rating systems, applicable ISO, ASTM, EN, and GB standards, common test items and sample types, laboratory procedures, and practical applications across the packaging, publishing, and labeling industries. Read on to learn how accredited third-party laboratories assess print durability and how the results are interpreted for quality control and product compliance.

Technical Overview

Color fastness evaluation is the systematic assessment of how well the printed colors on paper, paperboard, plastic film, textile, and other substrates withstand external influences without fading, bleeding, or transferring to adjacent surfaces. In the printing and packaging industries, poor fastness produces visible quality defects such as color rub-off during transport, staining between stacked products, illegible barcodes and expiration dates, and premature fading on retail shelves or outdoor displays. Fastness performance is governed by the pigment or dye chemistry in the ink, the resin binder system and its degree of drying or curing, ink film thickness, substrate absorption, and any protective finish such as overprint varnish or lamination.

Results are expressed through two principal rating scales. The grey scales defined in ISO 105-A02 (change in color) and ISO 105-A03 (staining) grade performance from 1, meaning severe change or heavy staining, to 5, meaning no visible effect, with intermediate half-steps. For light exposure, the blue wool reference scale grades fastness from 1, very low, to 8, outstanding, and forms the basis of ISO 12040 for graphic prints. Instrumental color difference values, expressed as delta-E, measured with a spectrophotometer supplement the visual ratings and provide objective, repeatable data for quality documentation.

• ISO 12040 — Graphic technology, assessment of light fastness of prints using filtered xenon arc lamp exposure
• ISO 2836 — Graphic technology, determination of the resistance of prints to liquids and chemical agents
• ASTM D5264 — Abrasion resistance of printed materials using a motorized reciprocating rub tester
• ISO 105-X12 and JIS L 0849 — Color fastness to rubbing, adapted for prints on flexible substrates
• ISO 105-A02 and ISO 105-A03 — Grey scales for assessing change in color and staining
• GB/T 7705, GB/T 7706, GB/T 7707, and GB/T 17497 — Chinese national standards covering decorative prints produced by lithographic, relief, gravure, and flexographic processes

Testing Samples

Paper and Paperboard Prints

This category includes books, magazines, folding cartons, corrugated shipping boxes, paper bags, and commercial print produced by offset lithography, gravure, flexography, screen printing, or digital processes. Typical concerns are dry and wet rub resistance on folding lines and cut edges, color set-off between stacked sheets, and bleed resistance when the package contacts moisture. The colorfastness requirements of the GB/T 7705 to GB/T 7707 series are frequently applied to these products.

Flexible Packaging Films

Surface-printed and reverse-printed polyethylene, polypropylene, and polyester films, whether laminated or unlaminated, are evaluated for rub fastness, blocking resistance under roll pressure, and resistance to the packaged contents, such as oils, detergents, or acidic food simulants. Incomplete solvent evaporation or inadequate curing of the ink layer is the most common cause of failure in these structures.

Labels and Self-Adhesive Materials

Labels for beverage bottles, cosmetics, and logistics applications must tolerate condensation, ice-water immersion, and high-speed rubbing on filling lines. Testing typically combines wet rub fastness, water immersion bleed resistance, and light fastness for products displayed under strong retail or window lighting.

Decorative and Specialty Prints

Wallpaper, decorative laminates, floor coverings, outdoor signage, printed textiles, and heat-transfer decals are dominated by light fastness and weathering requirements because the printed surface is exposed to daylight, UV radiation, and humidity for extended periods.

Testing Items

Depending on the end use of the printed article, accredited third-party laboratories typically perform the following fastness-related determinations:

• Color fastness to dry rubbing and wet rubbing
• Color fastness to water immersion and surface bleed
• Color fastness to organic solvents such as ethanol, isopropanol, acetone, and ethyl acetate
• Color fastness to acids, alkalis, soap, and detergent solutions as listed in ISO 2836
• Light fastness under filtered xenon arc radiation, rated against blue wool references
• Weathering resistance under fluorescent UV or xenon exposure with humidity cycling
• Heat resistance, blocking, and set-off under pressure at elevated temperature
• Scratch and abrasion resistance of the printed surface
• Color transfer to adjacent surfaces in stacked sheets, rolls, and wrapped goods
• Fastness to saliva and perspiration for children's books, toys, and articles with prolonged skin or mouth contact

Testing Methods

Rub Fastness Testing

In the reciprocating rub test based on ASTM D5264, the printed specimen is secured on a flat bed while an unprinted counter substrate, attached to a weighted head of typically 1.8 kg, strokes the surface for an agreed number of cycles. The wet variant repeats the procedure with a water-saturated counter substrate. For prints on textiles and flexible webs, a crockmeter procedure adapted from ISO 105-X12 is used, in which a standard cotton cloth rubs the surface under a defined force. Transfer is assessed visually with the grey scale for staining per ISO 105-A03 or instrumentally by measuring the color difference of the counter substrate.

Light Fastness Testing

Following ISO 12040, specimens and a set of blue wool references are exposed side by side in a xenon arc chamber equipped with daylight filters. Exposure proceeds in stages until the specimen shows a contrast between exposed and unexposed areas corresponding to the defined grey-scale endpoint. The blue wool reference that exhibits a comparable change identifies the light fastness rating from 1 to 8. Prints intended for prolonged indoor display generally require ratings of 3 to 4, while outdoor applications demand 6 or higher.

Resistance to Water and Chemical Agents

ISO 2836 specifies procedures in which the printed surface is contacted with a defined agent, such as distilled water, dilute acid, alkali, soap or detergent solution, alcohol, or edible oil, using soaked filter paper or immersion under controlled time and temperature. After drying, the specimen is evaluated for change in color with the grey scale per ISO 105-A02, and the staining of the contacting material is evaluated per ISO 105-A03.

Instrumental Color Difference Assessment

Spectrophotometric measurement conforming to ISO 13655 geometry and ISO 11664 colorimetry provides delta-E values that quantify fading or transfer independent of operator judgment. ISO 105-A05 and related instrumental procedures allow conversion of measured color differences into equivalent grey-scale ratings, which is particularly useful for audit trails and statistical process control.

Weathering and Heat Resistance Testing

Accelerated weathering under ISO 4892-2 xenon or ISO 4892-3 fluorescent UV conditions combines radiation, temperature, and moisture to simulate long-term exposure for outdoor prints. Blocking and set-off are evaluated by stacking printed samples under a defined load at elevated temperature, typically between 40 and 60 degrees Celsius, for 24 hours, then assessing tackiness and ink transfer between the contacting surfaces.

Applications

Color fastness evaluation supports quality assurance and compliance decisions throughout the printing supply chain:

• Release testing of folding cartons, labels, and flexible packaging before high-speed filling, converting, or distribution
• Verification that inks, coatings, and substrates meet buyer specifications and national print quality standards such as the GB/T 7705 series
• Durability qualification of labels for beverages, cosmetics, and chemical products exposed to water, condensation, and rubbing
• Safety assessment of children's books, toys, and stationery, where colorant transfer requirements appear in the EN 71 toy safety series and GB 6675
• Performance validation of outdoor signage, vehicle graphics, wallpaper, and decorative laminates under light and weathering
• Incoming inspection and ink system comparison during product development, as well as technical evidence for resolving commercial disputes

FAQ

What does print color fastness mean?

It is the ability of a printed color to resist change in hue, depth, or strength, and to resist transfer to other surfaces, when the print is subjected to mechanical action, light, moisture, heat, or chemicals during processing, distribution, and use.

How are color fastness results expressed?

Rubbing, water, and chemical fastness are graded on grey scales from 1 to 5, where 5 means no visible change or staining. Light fastness is graded from 1 to 8 using blue wool references. Instrumental results are reported as color difference values, which can be correlated to grey-scale ratings.

What is the difference between dry and wet rub fastness?

Dry rub testing assesses transfer from the printed surface to a dry counter substrate, simulating abrasion in stacking and transport. Wet rub testing uses a water-wet counter substrate and is more severe, because moisture softens water-sensitive binders and promotes bleeding; it is critical for packaging exposed to condensation or refrigeration.

What rating is considered acceptable?

Requirements depend on the product specification, but common commercial benchmarks are grey-scale grade 4 or higher for dry rub and grade 3 or higher for wet rub and staining, with higher demands for premium and safety-critical applications. Light fastness of at least blue wool grade 3 is typical for indoor retail display.

Why do prints fade, and how can fastness be improved?

Fading occurs when the colorant absorbs UV and visible radiation and degrades chemically; dye-based and certain organic pigments fade faster than inorganic pigments or carbon black. Fastness can be improved by selecting high-lightfast pigments, ensuring complete ink curing or drying, priming absorbent substrates, and protecting the surface with overprint varnish or lamination.

How should samples be prepared for testing?

Specimens should be taken from finished production, kept clean and uncreased, and conditioned in a standard atmosphere of 23 plus or minus 2 degrees Celsius and 50 plus or minus 5 percent relative humidity before evaluation, so that results reflect the condition of the product as delivered.