Fusible Interlining Testing

Fusible interlining testing mainly conducts scientific testing and analysis on peeling strength, washing resistance, thermal shrinkage, handle and style, glue penetration and reverse penetration, and dimensional change under dry heat/wet heat, 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

Peeling strength: Refers to the force required when the fusible interlining is peeled from the fabric, and is the core indicator for measuring the bonding firmness. The test usually simulates the peeling action suffered by the garment during wearing and washing, to evaluate the bonding durability of the interlining with fabrics of different materials (such as cotton, polyester and wool). It is the key basis for judging the service performance of the interlining fabric.

Washing resistance: The key item for evaluating the performance retention ability of the fusible interlining after multiple washes. The test methods include simulating household washing and commercial dry cleaning, mainly observing the decay rate of the peeling strength after washing, the appearance changes (such as blistering and delamination) and the dimensional stability, which are directly related to the service life and appearance retention of the garment.

Thermal shrinkage: An indicator for measuring the dimensional change of the fusible interlining during hot pressing bonding and the subsequent heat treatment process. It includes the heat shrinkage rate and the shrinkage rate after cooling, and its value directly affects the flatness and dimensional stability of the interlining part of the garment. It is an important parameter for controlling the processing precision of the garment and avoiding wrinkling or deformation.

Handle and style: An objective evaluation of the subjective feelings such as the softness, stiffness and drape of the fabric after the interlining is bonded. It is usually quantified through the handle touch of professional raters or fabric style instruments, to meet the special style requirements of different garments (such as suits needing stiffness and underwear needing softness).

Glue penetration and reverse penetration: Tests whether the hot-melt adhesive penetrates the face of the fabric (glue penetration) or migrates to the back side of the interlining (reverse penetration) during hot pressing. Glue penetration will affect the appearance and handle of the fabric, and reverse penetration may cause pollution of the bonding machine or subsequent processes. It is assessed by visual inspection, microscope observation or comparison with a standard staining scale.

Dimensional change under dry heat/wet heat: Separately tests the dimensional stability of the fusible interlining under dry heat (such as ironing) and wet heat (such as steam ironing and steaming) conditions. This is particularly important for high-grade garments that need finishing (such as pressing and steam finishing), because an unstable interlining will cause deformation of the garment parts.

Free formaldehyde content: In accordance with the ecological textile safety specifications, the content of free formaldehyde released by the fusible interlining is tested. The water extraction method is usually adopted, and a spectrophotometer is used for determination, to ensure that it meets the limit requirements of the national standard (such as GB 18401) or the international ecological standards (such as OEKO-TEX Standard 100), protecting the health of consumers.

Testing Scope

Woven fusible interlining: The testing objects include woven interlinings with cotton, polyester-cotton, polyester filament and other fabrics as the base. Testing needs to focus on their mechanical properties in the warp and weft directions, dimensional stability, and the bonding compatibility with heavy fabrics such as high-grade suits and overcoats, evaluating their performance under complex stresses.

Knitted fusible interlining: Mainly for interlinings with weft-knitted or warp-knitted fabrics as the base. The testing focus is on their excellent elastic recovery rate, extensibility and soft handle, evaluating the followability after bonding with knitted fabrics and elastic fabrics, and whether the inherent elasticity and comfort of the fabric will be affected.

Nonwoven fusible interlining: Tests the nonwoven base interlinings made of chemical fibres through processes such as thermal bonding and needle punching. For this type of interlining, testing needs to focus on its isotropy and soft and light characteristics, as well as whether it is prone to deformation or strength loss under different washing conditions. It is commonly used in shirts and casual wear.

Classification by hot-melt adhesive type: The testing scope covers interlinings with different hot-melt adhesive coatings such as polyamide (PA), polyethylene (PE), polyester (PES) and ethylene-vinyl acetate copolymer (EVA). According to the adhesive characteristics, its optimum bonding temperature, washing type (washing or dry cleaning) and chemical resistance (such as resistance to organic solvents) need to be tested.

Classification by coating process: Covering fusible interlinings with different coating methods such as powder scattering, powder dot, paste dot, double dot and film. Testing needs to evaluate the uniformity of the adhesive distribution of different coating patterns, the air and moisture permeability after bonding, and the slight influence of the dot coating on the fabric handle.

Special function fusible interlining: Including products with additional functions such as waterproofness, flame retardancy, antistatic and antibacterial properties. In addition to the conventional items, special tests need to be carried out in accordance with the relevant functional standards (such as GB/T 5455 for flame retardancy and GB/T 12703 for antistatic properties), verifying the functional effectiveness and durability.

Testing Methods

Peeling strength test method (strip method): In accordance with the standards GB/T 23327 or ISO 2411, the fusible interlining is pressed and bonded with a standard fabric at a certain temperature, pressure and time to make a specimen of the specified width. On an electronic fabric strength tester, a 180° or T-type peeling is carried out at a constant speed (such as 100 mm/min), and the average force value during the peeling process is recorded, with the unit being N/(5 cm).

Washing resistance test method: In accordance with the standard series such as GB/T 8629, a standard washing machine, detergent and set program (such as temperature, time and mechanical action) are used for multiple washes. The dry cleaning test is in accordance with GB/T 19981, using perchloroethylene solvent to simulate commercial dry cleaning. After each wash and drying, the peeling strength is separately tested and compared with the initial value, and the retention rate is calculated.

Thermal shrinkage test method (dry heat/wet heat): For the dry heat shrinkage test, the specimen is usually placed in an oven at a specified temperature (such as 150 ℃±2 ℃) for a certain time (such as 30 min) after pre-conditioning, and the dimensional change is measured after cooling. For the wet heat shrinkage test, steam ironing or a steaming apparatus can be used to measure the dimensions before and after steaming, calculating the shrinkage percentage in the warp and weft directions.

Glue penetration and reverse penetration assessment method: For the glue penetration assessment, the interlining is usually pressed and bonded with a dark-coloured standard fabric (such as black polyester silk), and after cooling, it is observed with a magnifying glass under a standard light source whether there are adhesive particles or adhesive marks on the face of the fabric. For the reverse penetration assessment, the interlining is pressed with a clean aluminium foil, and it is observed whether there is adhesive transfer on the aluminium foil, or a grey scale is used to assess the staining grade.

Free formaldehyde determination (water extraction method): In accordance with GB/T 2912.1, the specimen is extracted in a 40 ℃ water bath for a certain time, and the extract reacts with the acetylacetone reagent for colour development. A UV-visible spectrophotometer is used to measure the absorbance at the wavelength of 412 nm, and by comparing with the standard working curve, the content of free formaldehyde in the specimen is calculated (mg/kg).

Handle and style instrumental assessment method: Fabric style evaluation systems such as KES-F or FAST are adopted. By testing multiple physical and mechanical indicators such as the bending stiffness, shear stiffness, compression work and surface friction coefficient of the fabric, the style characteristics such as the stiffness, smoothness and fullness of the fabric after bonding are comprehensively and quantitatively evaluated, realizing the objectification of the subjective handle.

Testing Standards

Domestic Standards:

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

2. GB/T 2912.1, Textiles — Determination of formaldehyde — Part 1: Free and hydrolysed formaldehyde (water extraction method)

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

4. GB/T 5455, Textiles — Burning behaviour — Determination of damaged length, afterglow time and afterflame time

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

6. GB/T 3921-2008, Textiles — Tests for colour fastness — Colour fastness to washing with soap or soap and soda

International Standards:

1. ISO 2411, Rubber- or plastics-coated fabrics — Determination of coating adhesion

2. ISO 105, Textiles — Tests for colour fastness

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

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

Electronic fabric strength tester: The core equipment for mechanical property tests such as the peeling strength and tensile strength. It is equipped with pneumatic or mechanical grips, peeling accessories, a high-precision sensor and a data acquisition system, can output the force-displacement curve, and automatically calculate key data such as the peak value and average value, meeting various standards such as GB, ISO and ASTM.

Standard pressing machine: The key equipment for preparing standard peeling specimens. It is required that the temperature control of the upper and lower platens is precise (±2 ℃), the pressure is uniform and adjustable (such as 0.3-0.5 MPa), and the timing is accurate. It can simulate the bonding process conditions of mass production, ensuring that the test specimens are consistent with the actual application state and ensuring the comparability of the test results.

Fully automatic shrinkage testing machine: A washing resistance testing device integrating washing, dewatering and drying. It can preset multiple international standard washing programs (such as AATCC and ISO), precisely control the water temperature, water level, agitation action and drying conditions, realizing the standardization and high repeatability of the washing resistance test and greatly improving the testing efficiency.

Constant temperature and humidity chamber and pre-conditioning device: Used for the equilibrium treatment of the test specimens under standard atmospheric conditions (such as temperature 20±2 ℃ and relative humidity 65±4%). Before all physical property tests, the specimens need to be conditioned to the moisture equilibrium under these conditions, to eliminate the influence of the environmental temperature and humidity on the test results (especially the shrinkage and strength).

UV-visible spectrophotometer: The analytical instrument for the determination of chemical contents such as free formaldehyde. It is required to have high wavelength accuracy and good photometric repeatability. Combined with pretreatment equipment such as constant temperature water bath shakers and precision pipettes, it can accurately and rapidly complete the colour development reaction and absorbance determination, and is essential equipment for ecological safety testing.

Fabric style instrument/fabric handle evaluation system: Such as the KES-FB system, including multiple dedicated testers for tensile and shear, bending, compression, surface friction and so on. Through multi-parameter comprehensive measurement, the mechanical properties and handle style of the fabric after bonding are fully quantified, providing precise and objective data support for the selection of the interlining for high-grade garments.

Digital thickness gauge and mass balance: Used to test the basic physical indicators of the fusible interlining. The thickness gauge can precisely measure the thickness of the interlining and after bonding with the fabric (accuracy 0.01 mm). The electronic balance (accuracy 0.001 g) is used to measure the mass per unit area (mass), and these are the basic parameters for controlling the specification and cost of the interlining.