Perspiration Color Fastness Tester Operation Guide: Principles, Procedure, and Evaluation

The perspiration color fastness tester is an essential laboratory instrument used to evaluate how resistant dyed and printed textiles are to artificial human sweat under controlled temperature and pressure conditions. This article provides a complete technical guide to the operating experiment, covering working principles, applicable standards such as ISO 105-E04, AATCC 15, and GB/T 3922, specimen preparation, step-by-step operating procedures, result evaluation, and practical applications in textile quality control.

Technical Overview

The perspiration color fastness tester, also known as a perspirometer, is a laboratory device that simulates the effect of human sweat on colored textiles. During wear, garments such as sportswear, underwear, shirts, and socks are frequently exposed to perspiration, which can cause dye migration, color fading, and staining of adjacent materials. The tester reproduces this environment by immersing a composite textile specimen in artificial perspiration solution and then subjecting it to a defined pressure and elevated temperature.

A typical instrument consists of a heated chamber, a set of acrylic or stainless-steel plates, a loading weight, and a specimen frame that can hold multiple composite specimens simultaneously. The standard pressure applied is approximately 12.5 kPa, achieved by a mass of about 5 kg acting over the 100 mm × 40 mm specimen area, while the chamber maintains a constant temperature of 37 ± 2 °C to simulate human body temperature.

The experiment is governed by several internationally recognized standards, including ISO 105-E04, AATCC 15, GB/T 3922, and JIS L 0848. These standards define the composition of artificial sweat solutions, specimen dimensions, soaking duration, pressure, temperature, testing time, and the grey scale method used to assess color change and staining.

• Temperature control range: typically ambient +5 °C to 60 °C with an accuracy of ±2 °C
• Standard testing temperature: 37 ± 2 °C (ISO/GB) or 38 ± 1 °C (AATCC)
• Applied pressure: approximately 12.5 kPa using a calibrated loading mass
• Specimen capacity: usually 10 to 21 composite specimens per test run
• Test duration: 4 hours for ISO and GB methods, 6 hours for the AATCC method

Testing Samples

Dyed and Printed Fabrics

Fabric samples are the most common test materials. A specimen measuring 100 mm × 40 mm is cut parallel to the warp and weft directions and sewn or stapled face-to-face with multifibre adjacent fabric, or sandwiched between two single-fibre adjacent fabrics as specified by the relevant standard.

Yarns and Fibers

Yarn samples are wound tightly onto a rigid frame or knitted into a small swatch before a 100 mm × 40 mm specimen is cut. Loose fibers are combed and pressed into a thin, uniform sheet of the same dimensions so that a consistent test surface is obtained.

Garments and Components

Finished products such as T-shirts, socks, sportswear, linings, sewing threads, and labels can be tested by cutting specimens directly from the article. This verifies the fastness performance of the complete product rather than only the bulk fabric.

Adjacent Fabrics

Multifibre adjacent fabric, typically containing wool, acrylic, polyester, nylon, cotton, and acetate stripes, is used to capture staining from the specimen. Alternatively, two single-fibre adjacent fabrics are used: one made of the same fiber as the specimen and one made of the fiber specified by the standard.

Testing Items

The primary testing item is color fastness to perspiration, evaluated separately for acidic and alkaline artificial sweat, since human perspiration can vary in pH depending on physical condition and body region. The results include two independent ratings: color change of the specimen itself and staining of the adjacent fabric. The same instrument can also be adapted for related fastness tests by changing the test solution.

• Color fastness to acid perspiration (pH 5.5 ± 0.2 per ISO 105-E04)
• Color fastness to alkaline perspiration (pH 8.0 ± 0.2 per ISO 105-E04)
• Color fastness to acid perspiration (pH 4.3 ± 0.2 per AATCC 15)
• Color fastness to water (ISO 105-E01) and seawater (ISO 105-E02) using the same perspirometer
• Staining assessment on each fiber stripe of the multifibre fabric

Testing Methods

Preparation Before the Experiment

Prepare fresh artificial perspiration solutions immediately before use. For the ISO method, dissolve 0.5 g of L-histidine monohydrochloride monohydrate, 5 g of sodium chloride, and 2.2 g of disodium hydrogen orthophosphate dihydrate in one liter of distilled water. Divide the solution into two portions: adjust one to pH 5.5 ± 0.2 with acetic acid solution for the acid test, and adjust the other to pH 8.0 ± 0.2 with sodium hydroxide solution for the alkaline test. Verify the pH with a calibrated pH meter, confirm the oven temperature at 37 ± 2 °C, and check that the loading mass and plates are clean and undamaged.

Specimen Preparation

Cut a 100 mm × 40 mm specimen from the sample and combine it with multifibre adjacent fabric of the same size by sewing along one short edge. Label each composite specimen clearly to distinguish acid and alkaline tests. Condition the specimens in a standard atmosphere before testing to ensure reproducible moisture content.

Immersion Procedure

Place the composite specimens flat in a shallow dish and pour in the artificial perspiration solution at a liquor ratio of 50:1. Keep the temperature at 37 ± 2 °C and allow the specimens to soak thoroughly for 30 minutes, pressing and turning them occasionally to ensure complete wetting. After soaking, remove excess liquid by running the specimen between two glass rods or by squeezing uniformly, so that the specimen retains a controlled and consistent amount of solution.

Loading and Heating

Place each wet composite specimen between two acrylic plates with the multifibre fabric in full contact with the test specimen. Stack the assemblies in the perspirometer frame between the base plate and the loading weight, applying a pressure of approximately 12.5 kPa. Lock the frame, transfer it into the heated chamber pre-set at 37 ± 2 °C, and maintain the temperature for 4 hours (or 38 ± 1 °C for 6 hours under a 4.54 kg mass when following AATCC 15).

Drying and Evaluation

After the specified time, remove the frame, release the pressure, and separate the composite specimens. Dry them in air at a temperature not exceeding 60 °C, keeping the specimen and adjacent fabric in their relative positions and protecting them from direct light. Once dry, assess the color change of the specimen and the staining of each adjacent fiber using the grey scales: the scale for color change (ISO 105-A02) and the scale for staining (ISO 105-A03), each ranging from grade 5 (no visible change) to grade 1 (severe change). Instrumental colorimetric evaluation may also be used for objective results.

Key Operational Precautions

• Use freshly prepared perspiration solutions and verify the pH before every test, as incorrect pH is a leading cause of invalid results
• Ensure uniform wetting and consistent wet pick-up across specimens to guarantee comparability
• Do not exceed the drying temperature of 60 °C, as excessive heat can alter dye behavior and distort ratings
• Calibrate the oven temperature, pressure mass, and grey scales regularly, and maintain traceable records for accreditation audits
• Evaluate results promptly after drying and under standardized lighting conditions in a color assessment cabinet

Applications

Perspiration fastness testing is widely applied across the textile supply chain. Fabric mills and dye houses use it to verify dye recipes and process stability, garment manufacturers use it for incoming material inspection, and brand retailers specify minimum fastness grades, commonly grade 3–4 or above, in their product specifications. Accredited third-party laboratories perform this test for export compliance, product certification, and dispute resolution. Typical end-use products include sportswear, underwear, baby clothing, socks, linings, medical textiles, and bedding, all of which involve prolonged skin contact where sweat resistance is critical to both appearance and consumer safety.

FAQ

What is the principle of the perspiration color fastness test?

The test simulates prolonged contact between colored textiles and human sweat. A composite specimen is soaked in acid or alkaline artificial perspiration, placed under standardized pressure, and kept at body temperature for several hours. The degree of color change in the specimen and staining on adjacent fabrics is then rated on grey scales from 1 to 5.

Why are both acid and alkaline perspiration tested?

Human sweat varies in pH: fresh perspiration is mildly acidic, while bacterial decomposition can make it alkaline. Dyes respond differently to each condition, so both tests are required to fully characterize fastness performance, particularly under ISO 105-E04 and GB/T 3922.

What rating is considered acceptable?

Grade 5 indicates no visible color change or staining, while grade 1 indicates severe change. Most commercial requirements demand a minimum of grade 3 to 4 for staining and grade 4 for color change, though exact limits depend on the product type and buyer specification.

Can one instrument perform other fastness tests?

Yes. The same perspirometer frame, plates, and loading system can be used for color fastness to water (ISO 105-E01), seawater (ISO 105-E02), and chlorinated pool water by simply changing the immersion solution and following the corresponding standard procedure.

What are common causes of failed or inconsistent results?

Frequent causes include incorrect solution pH, expired or contaminated artificial perspiration, uneven wet pick-up, inaccurate oven temperature, insufficient or excessive pressure, drying at excessively high temperature, and evaluation under non-standard lighting. Strict adherence to the standard procedure and regular instrument calibration minimize these errors.