Cotton Pants and Jacket Testing

Cotton garment and trousers inspection mainly conducts scientific testing and analysis on fibre content testing, colour fastness testing, pilling performance testing, dimensional stability, pH value determination, tearing strength and breaking strength testing, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Fibre content testing: In accordance with the standards such as GB/T 2910, the composition ratios of the cotton fibres and the other fibres (such as the polyester fibres and spandex) in the cotton garment and trousers fabric are quantitatively analysed through the chemical dissolution method or microscope observation method. It is the basic item for judging the true material, value and whether it conforms to the marking regulations of the product.

Colour fastness testing: Evaluates the colour retention ability of the cotton garment and trousers under the specific conditions. The key items include the colour fastness to soaping, colour fastness to rubbing, colour fastness to perspiration and colour fastness to light. The test results directly affect whether the garment will fade or contaminate the other clothes during washing, wearing and daily use.

Pilling performance testing: Simulates the phenomenon that the fibre ends on the fabric surface protrude to form the fuzz or entangle into pills due to the friction during the wearing of the cotton garment and trousers. A Martindale abrasion tester or circular locus pilling tester is usually used for the testing, and the rating is carried out according to the standard sample photos. It is an important indicator for evaluating the appearance durability.

Dimensional stability (shrinkage) testing: By measuring the dimensional changes of the cotton garment and trousers before and after the standard washing (such as the GB/T 8629 procedure) and drying, the shrinkage in the warp and weft directions is calculated. This testing is directly related to the accuracy of the purchase size of the consumers and the fit after wearing.

pH value determination: Detects the acidity and alkalinity of the aqueous extract of the cotton garment and trousers fabric. According to the mandatory standard GB 18401, the pH value of the textile directly contacting the skin should be between 4.0 and 8.5. If the pH value is too high or too low, it may irritate the skin, affecting the wearing comfort and safety.

Tearing strength and breaking strength testing: The tearing strength of the fabric is tested by the falling pendulum method (Elmendorf method) or trapezoid method respectively, and the breaking strength of the fabric is tested by a constant-rate-of-extension (CRE) tensile testing machine. These physical and mechanical property indicators directly reflect the durability and damage resistance of the cotton garment and trousers fabric under the force.

Testing Scope

Main fabric body: The testing scope covers the main fabric parts of the cotton garment and trousers, including the outer fabric, middle thermal insulation layer (such as the batting sheets) and inner lining. The samples need to be taken separately to evaluate their respective fibre compositions, colour fastness and strength, ensuring the balanced overall quality.

Filling materials: For the cotton garment and trousers with the filling cotton (such as the fluffy cotton and down-like cotton), the testing scope needs to extend to the fillings. The key tests are their fibre content, oil content, loftiness and compression recovery rate, to evaluate the thermal insulation performance and durability.

Auxiliary materials and accessories: The testing objects include the auxiliary materials such as the zippers, buttons, Velcro, elastic bands and sewing threads. Their durability and colour fastness need to be evaluated, and in accordance with the standards such as GB 31701, the safety items such as the tensile strength and sharp edges of the accessories of the infant and children products are tested.

Sewn parts: The key testing is carried out on the seam parts, with the main item of the seam strength (or seam slippage). Through the tensile testing, the firmness of the sewing threads and the sewing process is evaluated, preventing the problems such as the seam opening and seam bursting during wearing.

Overall finished product: The testing is carried out from the perspective of the final finished product, such as the appearance retention after washing, twisting rate and overall dimensional change of the whole garment. This can comprehensively reflect the final performance of the fabric, auxiliary materials and process under the synergistic action.

Specific functions: If the cotton garment and trousers claim the special functions, such as the waterproof, windproof, anti-static and antibacterial, the testing scope needs to be correspondingly expanded to these claimed items, carrying out the verification testing in accordance with the relevant product standards or method standards.

Testing Methods

Chemical analysis method (fibre content): In accordance with the GB/T 2910 series standards, for the different fibre combinations, the specific chemical reagents (such as the sulfuric acid and sodium hypochlorite) are selected to selectively dissolve one of the components, and the content of each component is calculated by weighing the mass of the remaining substance. For the samples with complex blends, the microscope method is often combined for the qualitative and quantitative analysis.

Instrumental friction method (colour fastness): The colour fastness to rubbing testing follows GB/T 3920, using a rubbing fastness testing machine. The dry and wet standard white cloths are respectively used to carry out the reciprocating friction on the sample with the specified pressure and stroke, and finally the staining grade of the white cloth is rated with the grey scales.

Simulated washing method (dimensional stability): In accordance with GB/T 8629 "Textiles — Domestic washing and drying procedures for textile testing", the marked sample is placed in a standard washing machine, washed with the specified water temperature, detergent, mechanical action and rinsing procedure, then dried by the specified method (line drying, flat pressing or tumble drying), and finally the dimensional change rate is measured and calculated.

Martindale method (pilling and abrasion): In accordance with GB/T 4802.1 (pilling) and GB/T 21196 (abrasion), the specimen is rubbed with the standard abrasive in a circular motion on a Martindale abrasion tester under the specified pressure. After the specified number of times, the pilling degree is rated against the standard sample photos under a standard light cabinet.

Water extraction method (pH value): In accordance with GB/T 7573, the sample is cut into pieces and oscillating-extracted with the grade 3 water under the specific conditions, and the pH value of the extract is measured with a calibrated pH meter. Before the testing, the glassware needs to be fully cleaned, and the contamination of the sample by the hand perspiration needs to be avoided, to ensure the accurate results.

Mechanical property testing method (strength): The breaking strength and elongation at break testing follow GB/T 3923.1, using a constant-rate-of-extension (CRE) type tensile testing machine to stretch the specimen of the specified size at a constant rate until it breaks, recording the maximum force value and elongation. The tearing strength testing follows GB/T 3917, carried out by the impact pendulum method or trapezoid method.

Testing Standards

Domestic Standards:

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

2. GB/T 3923.1, Textiles — Tensile properties of fabrics — Part 1: Determination of breaking force and elongation at breaking force using the strip method

3. GB/T 3917, Textiles — Determination of tear properties of fabrics

4. GB/T 4802.1, Textiles — Determination of fabric propensity to surface pilling — Part 1: Circular locus pilling tester method

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

6. GB/T 7573, Textiles — Determination of pH of the aqueous extract

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

8. GB 31701, Safety technical code for infants and children textile products

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

International Standards:

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

2. ISO 13937, Textiles — Tear properties of fabrics

3. ISO 12947, Textiles — Determination of the abrasion resistance of fabrics by the Martindale method

4. 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 fineness tester and microscope: Used for the qualitative identification and partial quantitative analysis of the fibre composition. A biological microscope can observe the longitudinal and cross-section morphology of the fibres; a fibre fineness tester can combine the image analysis software to automatically measure the fibre diameter, and is important for the maturity evaluation of the cotton fibres.

Standard light source colour matching cabinet: Provides the standard light sources such as D65, TL84, CWF and UV, and is the essential equipment for the colour fastness rating (change in colour and staining), colour difference evaluation and pilling rating. It ensures that the rating personnel carry out the visual judgement under the stable environment of the different light sources without the interference of the external light.

Fabric strength testing machine: A general-purpose electronic universal material testing machine, equipped with the different fixtures and sensors, which can complete the various mechanical property tests such as the tensile breaking strength, tearing strength, seam strength and peel strength of the fabric, with the precise data and the complete stress-strain curve.

Martindale abrasion/pilling tester: Used to simulate the continuous and multi-directional friction of the fabric in the daily use. The instrument drives the friction heads to move in the Lissajous pattern on the abrasion table, and can carry out the abrasion resistance and pilling performance testing of the fabric simultaneously or separately.

Automatic shrinkage testing machine and drying equipment: Including the standard shrinkage washing machine, drying oven (for the oven method drying), flat pressing machine or tumble dryer. These equipment can precisely control the parameters of the washing, spinning and drying, ensuring the condition reproducibility and result comparability of the dimensional stability testing.

pH meter and oscillating extraction device: A high-precision laboratory pH meter (with the precision of 0.01) is used to measure the pH value of the extract, and needs to be regularly calibrated with the standard buffer solutions. A constant temperature oscillating water bath or horizontal oscillator is used to extract the specimen at the standard temperature, ensuring the sufficient extraction and consistent conditions.

Constant temperature and humidity laboratory: It is not a single piece of equipment, but the standard environment for the sample conditioning and testing before the physical testing of the textile. The temperature of (20±2) ℃ and the relative humidity of (65±4)% are usually required. All the test samples need to be equilibrated in this environment for at least 24 hours, to eliminate the influence of the environmental temperature and humidity on the test results.