Pure Cotton Garment Fabric Testing

All-cotton garment fabric testing mainly conducts scientific testing and analysis on fibre composition content analysis, colour fastness testing, fabric structure physical property testing, dimensional stability, strength performance testing and pilling performance evaluation, objectively assessing the product quality grade and issuing a detailed test report within 3-7 working days, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Fibre composition content analysis: Chemical dissolution methods or microscope methods are used to quantitatively determine the actual content percentage of cotton fibre in the fabric, ensuring that it conforms to the declared "all-cotton" or "100% cotton" claims, and preventing the adulteration of other fibres (such as polyester fibre and viscose fibre) as inferior products.

Colour fastness testing: Evaluates the stability of the fabric colour under the action of various external factors, and is a key indicator for measuring the quality of the fabric. It mainly includes colour fastness to rubbing, colour fastness to perspiration, colour fastness to washing and colour fastness to light, etc., to ensure that the garment is not easy to fade or stain other clothes during wearing and washing.

Fabric structure physical property testing: Including the testing of basic physical parameters such as the warp and weft density, mass per square metre, yarn count and thickness of the fabric. These parameters directly affect the appearance style (such as thickness, thinness, density), handle, and the subsequent durability and wearability of the fabric, and are the basis for judging whether the fabric conforms to the design specifications.

Dimensional stability (shrinkage) testing: By simulating the household washing or commercial washing process, the length change rate of the fabric in the warp and weft directions after washing and drying is measured. This test is particularly important for all-cotton garments, because cotton fibres are prone to swelling after absorbing moisture, causing the fabric to shrink, which directly affects the fit and size retention of the garment.

Strength performance testing: Measures the ability of the fabric to resist damage from external forces, mainly including tensile breaking strength, tearing strength and bursting strength. This is related to the durability and safety of the garment during wearing, especially for garment categories with higher requirements such as workwear and children's clothing.

Pilling performance evaluation: Through equipment such as the Martindale abrasion tester or the circular locus pilling box, the surface change of the fabric after friction during wearing is simulated, and its anti-pilling grade is rated. Although all-cotton fabric is relatively less prone to pilling than chemical fibres, some loose or short-fibre varieties still need attention to this property.

Formaldehyde content and pH value determination: These belong to the ecological safety indicator testing. Formaldehyde may come from processes such as anti-wrinkle finishing, and excessive amounts can irritate the skin; the pH value reflects the acidity and alkalinity of the fabric. Human skin is weakly acidic, and an excessive pH value can easily cause skin discomfort. These two items are mandatory requirements of domestic and foreign textile basic safety technical specifications (such as GB 18401).

Prohibited azo dyes and hazardous substance screening: Tests whether the fabric contains azo dyes that can decompose to release carcinogenic aromatic amines, as well as hazardous chemicals such as heavy metals (such as lead and cadmium) and phthalate plasticizers, ensuring that the garment complies with strict ecological and environmental protection standards such as the EU REACH and OEKO-TEX® STANDARD 100.

Testing Scope

Woven cotton fabrics: Including plain weaves (such as poplin and fine cloth), twill weaves (such as khaki and gabardine), and satin weaves (such as satin). Testing needs to pay attention to the differences in the warp and weft performance, the influence of the yarn configuration on the style, and the performance changes brought by the finishing processes (such as mercerizing and non-iron).

Knitted cotton fabrics: Including weft-knitted fabrics (such as single jersey, interlock and fleece fabrics) and warp-knitted fabrics. The testing focus is on their elasticity, extensibility, stitch density, and the problems such as snagging and laddering that may occur due to the loose structure. The shrinkage test method is also often different from that of woven fabrics.

Denim: As a special cotton fabric, in addition to the conventional items, testing particularly emphasizes its unique colour fastness (such as colour fastness to rubbing, light and ozone) and the warp tensile strength (related to the loom tension). At the same time, the influence of its washing processes (such as enzyme washing and stone washing) on the physical properties and safety indicators needs to be considered.

Raised cotton fabrics: Such as corduroy, velveteen and flannel. Testing needs to additionally focus on the firmness of the pile (such as the anti-fuzzing and pile loss performance under rubbing), the uniformity of the pile height, and the special handle and thermal insulation performance evaluation caused by the pile structure.

Functionally finished cotton fabrics: Cotton fabrics finished with special functions such as water repellency, oil repellency, soil release (three-proof), flame retardancy, antibacterial and UV resistance. The testing scope needs to be extended to the verification of the corresponding functional effects and their durability (such as the function retention rate after multiple washes), and to evaluate whether the finishing agents introduce new hazardous substances.

Semi-finished products and finished products at different processing stages: The testing scope covers the whole chain from yarn, grey fabric, printed and dyed finished fabric to the final garment. The testing focus of different stages is different. For example, the grey fabric focuses on the physical structure, while the finished product comprehensively covers all indicators of the physical properties, colour fastness and safety ecology.

Infant and children's cotton garments: For this type of product, the testing scope needs to implement stricter standards (such as GB 31701), adding physical safety testing items for accessories (buttons and zippers) such as the tension and torque, sharp points and edges, and cord safety, and the requirements for the limits of hazardous substances are more stringent.

Testing Methods

Fibre composition quantitative analysis (chemical method): In accordance with standards such as GB/T 2910 and ISO 1833, a specific solvent (such as 75% sulphuric acid dissolving cotton and retaining other fibres) is used to selectively dissolve one component in the mixed fibres, and the mass percentage of each component is calculated by weighing the residue. This method is the preferred method for arbitration and precise analysis.

Colour fastness testing (combination of instruments and grading): For the colour fastness to rubbing, a rubbing fastness tester is used. After the specimen is rubbed a specified number of times with a standard white cloth under a certain pressure, the staining grade is rated with a grey scale. For the colour fastness to washing, the specimen is sewn with a standard adjacent fabric, placed in a soap solution, mechanically agitated and washed at a specific temperature and time, and after drying, the change in colour and staining are separately rated.

Fabric structure physical property testing: For the warp and weft density, a fabric density glass is used to count the number of yarns in a specified area; for the mass per square metre, a precision balance is used to weigh the mass of the specimen of a specified area and convert it; the yarn count can be measured by the skein weighing method or the projection microscope method. These methods strictly follow the relevant basic method standards such as GB/T and ISO.

Shrinkage testing (dimensional change rate): The mainstream methods include the household washing method (such as GB/T 8629/ISO 6330) and the commercial washing method. Reference points are marked on the specimen, and after washing and drying (line drying, flat drying or oven drying) with a standard procedure, the distance change between the marked points is measured and the change rate is calculated. Before the test, the specimen needs to be conditioned to the moisture equilibrium.

Strength testing (mechanical method): For the tensile breaking strength, a constant rate of extension (CRE) type strength tester is used. The strip specimen or grab specimen is clamped and stretched at a constant rate until breakage, and the maximum force is recorded. For the tearing strength, the pendulum method or the tongue method is commonly used to measure the force required for the fabric to extend an initial cut. The tests are all carried out under standard temperature and humidity conditions.

Chemical analysis of hazardous substances: For the formaldehyde content, the liquid extraction method (such as the water extraction method) is adopted, and after colour development with acetylacetone, the absorbance is measured by a spectrophotometer for quantification. For the prohibited azo dyes, gas chromatography-mass spectrometry (GC-MS) is used for detection. After the dyes are reduced and cleaved, the types and contents of the generated aromatic amines are analysed.

Functional testing methods: For water repellency, the hydrostatic pressure method or the spray method is commonly used; for UV resistance, the UV transmittance is measured by a UV spectrophotometer and the UPF value is calculated; for antibacterial properties, the quantitative method (such as the absorption method) is adopted to inoculate specific bacterial strains, and after culturing, the antibacterial rate is calculated. The method selection needs to match the claimed functions and the applicable standards.

Testing Standards

Domestic Standards:

1. GB 18401-2010, National general safety technical code for textile products

2. GB/T 2910, Textiles — Quantitative chemical analysis

3. GB/T 8629, Textiles — Domestic washing and drying procedures for testing

4. GB/T 3920-2024, Textiles — Tests for colour fastness — Colour fastness to rubbing

International Standards:

1. ISO 6330, Textiles — Domestic washing and drying procedures for testing textiles

2. ISO 13934-1, Textiles — Tensile properties of fabrics — Part 1: Determination of maximum force and elongation at maximum force using the strip method

3. ISO 105, Textiles — Tests for colour fastness

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Fibre composition analysis system: The core equipment includes a precision analytical balance (accuracy 0.0001 g), a constant temperature water bath, a Soxhlet extractor or dedicated dissolution device, an oven and a desiccator, etc. A microscope (biological or projection type) is used to assist the qualitative identification of the fibre morphology, and is an important supplement to the chemical analysis method.

Colour fastness testing instrument series: Including washing fastness testing machines, rubbing fastness testers, perspiration fastness testers and light fastness test chambers (xenon arc lamp or carbon arc lamp), etc. The supporting equipment includes a standard light source cabinet (such as the D65 light source), and the grey scales for assessing the change in colour and staining and blue wool reference standards, ensuring objective and accurate grading.

Fabric physical property testers: Electronic fabric strength testers (for tensile, tearing and bursting tests), Martindale abrasion and pilling testers, fabric thickness gauges, fabric density glasses, circular sample cutters (for sampling of a standard area), and balances (for mass). The constant temperature and humidity laboratory is the prerequisite for ensuring the accuracy and comparability of these physical test data.

Shrinkage and appearance retention testing equipment: Standard household washing machines or commercial front-loading washing machines, tumble dryers or ovens, standard detergents, and drying racks (for line drying). The appearance smoothness appearance evaluation board after washing is used to assess the seam appearance and overall smoothness grade after washing.

Chemical safety indicator analysis instruments: UV-visible spectrophotometers (for the determination of formaldehyde and pH value), gas chromatography-mass spectrometry (GC-MS, for the analysis of trace organic toxins such as prohibited azo dyes and pesticide residues), atomic absorption spectrometers (AAS) or inductively coupled plasma mass spectrometers (ICP-MS, for the determination of heavy metal content).

Ecological and functional testing equipment: Hydrostatic pressure testers, spray-type waterproof testers, UV transmittance analysers (with an integrating sphere), constant temperature and humidity incubators and colony counters (for antibacterial testing), and vertical burning testers or oxygen index meters (for flame retardancy testing). These dedicated equipment provide technical means for verifying the additional properties of the product.

Laboratory environment guarantee system: This is the basis of all testing, including a high-precision constant temperature and humidity air conditioning system (usually maintaining a temperature of 20±2 ℃ and a relative humidity of 65±4%), an air purification system, a standard lighting system and a pure water preparation system. A stable environment is the key to ensuring the reproducibility and comparability of the physical test results of textiles.