AATCC 15 is the internationally recognized standard test method for measuring the colorfastness of dyed and printed textiles to perspiration, simulating how fabric colors react when exposed to acidic or alkaline human sweat. This article explains the testing principle, sample requirements, solution preparation, step-by-step procedure, evaluation criteria, and typical industrial applications of the AATCC 15 perspiration colorfastness test.
Technical Overview
AATCC Test Method 15, officially titled "Colorfastness to Perspiration," is a standardized laboratory procedure developed by the American Association of Textile Chemists and Colorists (AATCC). The method evaluates the resistance of the color of a textile material to the action of human perspiration, determining whether a colored fabric will bleed, fade, or stain adjacent materials during actual wear.
Human perspiration varies in chemical composition from person to person and over time. Fresh sweat is typically slightly acidic, while it becomes alkaline as bacterial decomposition progresses on the skin. To account for this variability, AATCC 15 specifies two test options: an acidic perspiration solution adjusted to pH 4.3 ± 0.2 and an alkaline perspiration solution adjusted to pH 8.0 ± 0.2. Both conditions must be tested and reported separately.
In the test, a colored specimen is soaked in artificial perspiration solution, placed in contact with a multifiber adjacent fabric, and kept under pressure at body temperature in a perspiration testing device (perspirometer) inside a laboratory oven. After exposure, the specimen is evaluated for color change and the adjacent fabric is evaluated for staining, both rated on the standard gray scales from Class 1 (severe) to Class 5 (negligible or none).
Testing Samples
Dyed and Printed Fabrics
The most common test subjects are woven, knitted, and nonwoven fabrics that have been dyed, printed, or otherwise colored. Typical specimen size is 60 mm × 60 mm (approximately 2.4 in × 2.4 in), cut to include all colors of a print pattern if applicable. Each color area should be evaluated independently whenever feasible.
Yarns and Fibers
Colored yarns can be tested by winding them close together on a suitable frame to form a compressed layer, or by braiding, to provide a uniform test surface. Loose dyed fibers may be combed and compressed into a small pad before testing.
Garments and Components
Finished garment components such as collars, cuffs, waistbands, linings, sewing threads, labels, and trims are frequently tested, since these areas are in direct contact with the skin and perspiration during wear.
Multifiber Adjacent Fabric
Each specimen is tested in contact with a multifiber test fabric (such as Multifiber No. 10, containing acetate, cotton, nylon, polyester, acrylic, and wool strips) of the same size. This allows the staining tendency of the specimen onto a full range of common fiber types to be assessed in a single test.
Testing Items
The AATCC 15 test measures two distinct performance characteristics:
- Color change of the specimen: The degree to which the original color of the tested material fades or shifts in hue after exposure to perspiration solution, rated using the AATCC Gray Scale for Color Change.
- Staining of adjacent materials: The degree to which color transfers from the specimen to each fiber component of the multifiber fabric, rated using the AATCC Gray Scale for Staining or the AATCC Chromatic Transference Scale.
- Effect classification: Both acidic and alkaline test results are graded from Class 5 (no visible change or staining) to Class 1 (severe change or heavy staining), usually reported to the nearest half-point increment.
Testing Methods
Preparation of Test Solutions
Artificial perspiration solutions are freshly prepared with distilled or deionized water. The acidic solution contains 0.5 g of histidine monohydrochloride monohydrate, 5 g of sodium chloride, and 2.2 g of sodium dihydrogen orthophosphate per liter, adjusted to pH 4.3 ± 0.2. The alkaline solution contains 0.5 g of histidine monohydrochloride monohydrate, 5 g of sodium chloride, and 5 g of disodium hydrogen orthophosphate per liter, adjusted to pH 8.0 ± 0.2. pH is verified with a calibrated pH meter.
Specimen Wetting
The specimen, assembled with the multifiber fabric, is immersed completely in the test solution at room temperature for 30 minutes, with occasional agitation and pressing to ensure thorough and uniform wetting. The wet assembly is then passed through squeeze rollers or pressed between blotting papers to achieve a wet pick-up of 100% ± 5% by mass.
Exposure Under Pressure and Heat
The wet assembly is placed between inert plastic or glass plates and loaded into a perspirometer. A constant force of 4.5 kg (10 lb) is applied to the specimen stack. The loaded device is placed in a laboratory oven maintained at 38°C ± 1°C (100°F ± 2°F), approximating human body temperature. Current editions of the standard specify an exposure time of 18 hours; note that earlier editions required only 6 hours, so specifications should always confirm the applicable version.
Drying and Evaluation
After the exposure period, the specimen is removed and air-dried at room temperature without wringing or oven drying, as excessive heat can distort the results. Once conditioned, the tested specimen is compared with an untreated original to assign a color change grade, and each fiber strip of the multifiber fabric is rated for staining. Evaluations are best performed in a standardized lighting environment such as a color assessment cabinet.
Reporting
The final report should state the test option (acid, alkaline, or both), the color change class, staining class for each adjacent fiber type, the multifie fabric used, the test duration and temperature, and any deviations from the standard procedure.
Applications
AATCC 15 is applied throughout the textile supply chain for product development, quality control, and regulatory compliance. Key applications include:
- Performance apparel: Sportswear, activewear, underwear, socks, and hosiery, which experience prolonged sweat contact during use.
- Everyday garments: Shirt collars, cuffs, linings, and waistbands where body contact is constant and staining complaints are common.
- Home and institutional textiles: Bed linens, mattress ticking, and towels that contact skin for extended periods.
- Dye and process optimization: Comparing dye classes, fixing agents, and after-washing procedures to improve perspiration fastness before bulk production.
- Buyer and brand compliance: Most major North American retailers specify minimum perspiration fastness requirements, commonly Class 4 for color change and Class 3 to 3-4 for staining, verified through AATCC 15 test reports.
- Failure analysis: Diagnosing customer complaints related to color bleeding, staining of white areas, and shade change in worn garments.
FAQ
What is the difference between AATCC 15 and ISO 105-E04?
Both methods evaluate perspiration colorfastness using similar apparatus and acid/alkaline solutions, but AATCC 15 uses an acidic solution at pH 4.3, while ISO 105-E04 uses pH 5.5. In addition, current AATCC 15 requires 18 hours at 38°C, whereas ISO 105-E04 specifies 4 hours at 37°C. Test results between the two methods are therefore not automatically interchangeable.
Why are both acidic and alkaline perspiration tested?
Because human sweat chemistry varies between individuals and changes over time, a fabric that performs well in acidic sweat may fail in alkaline sweat or vice versa. Testing both options provides a realistic assessment of real-world wear performance.
What equipment is required for AATCC 15 testing?
The essential equipment includes a perspirometer with a 4.5 kg weight, a laboratory oven capable of maintaining 38°C ± 1°C, a pH meter, precision balances, wet pick-up squeeze rollers, multifiber test fabric, freshly prepared perspiration solutions, and AATCC gray scales for evaluation.
What grade is considered a pass?
The standard itself does not set pass or fail limits; acceptance criteria are defined by buyers and product specifications. In commercial practice, a color change of Class 4 or better and staining of Class 3 or better on the critical adjacent fibers are typical minimum requirements.
Can AATCC 15 be performed on prints and multicolored fabrics?
Yes. When a specimen contains multiple colors, each color zone should either be tested as a separate specimen with its own multifiber fabric or positioned so that all colors contact the adjacent fabric, and the results for every color must be reported separately.