Impregnated Paper Laminated Wood Flooring Testing

Laminated floor (impregnated paper laminated wood flooring) testing mainly conducts scientific testing and analysis on surface abrasion resistance, formaldehyde emission, surface stain resistance, dimensional stability, internal bond strength and surface bonding strength, 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

Surface abrasion resistance: Used to evaluate the ability of the floor surface decorative layer to resist wear. Through a specific abrasion testing machine, under the specified load and rotational speed, the number of revolutions required for the surface to be worn through or the mass change before and after wear is observed. This item is directly related to the durability and service life of the floor in daily use, and is one of the key indicators for measuring the product quality grade.

Formaldehyde emission: This is a core health indicator related to indoor environmental safety. In accordance with national standards, the chamber method or the desiccator method is mainly adopted to simulate actual use conditions and determine the mass concentration of formaldehyde released into the air per unit area of the floor per unit time. Controlling formaldehyde emission is a mandatory test item for safeguarding consumer health and meeting green environmental requirements.

Surface stain resistance: Evaluates the ability of the floor surface to resist erosion and contamination by common pollutants (such as vinegar, coffee, shoe polish and ink). The specified pollutant is dropped on the surface of the specimen, and after a specified time, it is cleaned to observe whether there is contamination or discoloration on the surface. This item directly reflects the ease of cleaning and maintenance of the floor and the retention of aesthetics after long-term use.

Dimensional stability: Tests the expansion and shrinkage performance of the floor under changes in temperature and humidity. Usually, the specimen is treated in different humidity environments and the change rate of its length, width and thickness is measured. Excellent dimensional stability can effectively prevent problems such as excessive gaps, warping or cupping of the floor caused by environmental changes in use.

Internal bond strength: Used to evaluate the bonding strength between the fibers inside the floor substrate (usually high-density fiberboard). A tensile force is applied to the specific bonding surface of the specimen through a dedicated fixture, and the maximum tensile force per unit area at failure is determined. This indicator reflects the quality of the substrate itself and is the internal guarantee for preventing delamination and cracking of the floor in use.

Surface bonding strength: An indicator for measuring the firmness of the bond between the decorative impregnated paper and the substrate. A tensile testing machine is used to peel the decorative layer of a specified area from the substrate and record the maximum force required. Insufficient strength will cause the decorative layer to peel off, seriously affecting the appearance and service function of the floor.

Modulus of rupture and modulus of elasticity: These two items are important mechanical indicators for evaluating the load-bearing capacity and bending deformation resistance of the floor. The modulus of rupture reflects the ability of the floor to resist bending failure, while the modulus of elasticity characterizes its stiffness. Through the three-point bending test, a load is applied to the middle of the specimen until failure, thereby calculating the corresponding strength and modulus values.

Surface scratch resistance: Simulates the situation of sharp objects (such as sand and gravel and furniture casters) scratching across the floor surface, and evaluates its ability to resist scratches. A scratch needle or steel wool of a specific hardness is used to scratch across the specimen surface under the specified load and speed, and then the visibility and depth of the scratches are observed or measured.

Testing Scope

Product type coverage: The testing applies to all floors made by impregnating one or more layers of special paper with thermosetting amino resin, laying them on the surface of wood-based panel substrates such as particleboard and high-density fiberboard, adding a balance layer on the back, and forming by hot pressing. This includes products of different abrasion resistance grades such as household type (≥6000 revolutions) and commercial type (≥9000 revolutions), as well as products with various surface textures (such as embossed and synchronized grain).

Production process control: The testing scope runs through the key links of the product life cycle. From incoming material inspection (such as the basis weight and volatile content of the impregnated paper, and the density and moisture content of the substrate), to the monitoring of process parameters during production (such as hot pressing temperature, pressure and time), until the factory inspection and type inspection of the final finished product, forming a comprehensive quality control closed loop.

Circulation and use links: Testing is not limited to production enterprises, but also covers scenarios such as market supervision spot checks, consumer dispute arbitration, engineering acceptance and quality evaluation of old floors. For example, in construction project acceptance, sampling testing needs to be carried out on the floor entering the site to ensure that it meets the design contract and national standard requirements.

Performance dimension coverage: The testing scope comprehensively covers the physical and mechanical properties, environmental safety performance, durability performance and decorative performance of the product. Specifically, it includes but is not limited to dimensions, appearance, mechanical strength, surface performance, resistance (heat, light and chemicals) and hazardous substance limits, ensuring that the comprehensive quality of the product meets the use requirements.

Standard conformity verification: The core scope of testing is to verify whether the product complies with national and industry mandatory or recommended standards. In China, it is mainly based on the GB/T 18102-2020 "Laminated floor covering" standard, and may also involve mandatory environmental standards such as GB 18580-2025 "Indoor decorating and refurbishing materials — Limit of formaldehyde emission of wood-based panels and finishing products".

Products with special functions and uses: For products with special claims or functions, the testing scope needs to be correspondingly expanded. For example, for floors claiming functions such as "anti-static", "cigarette burn resistance" and "high water resistance", special tests such as electrostatic performance, cigarette burn resistance and water absorption thickness swelling need to be added to verify the truthfulness of the claims.

Testing Methods

Chamber method for determining formaldehyde emission: This is a precise method commonly used for arbitration and high-end products. A specimen with a surface area of 1 m² is placed in a climate chamber with strictly controlled temperature, humidity and air exchange rate. After the release becomes stable, air in the chamber is collected and the formaldehyde concentration is analyzed by the acetylacetone spectrophotometric method or high-performance liquid chromatography. This method can most realistically simulate the formaldehyde release condition of the floor in the actual indoor environment.

Surface abrasion resistance test (Taber method): The specimen is fixed on an abrasion testing machine, and grinding wheels of a specific specification (usually CS-10 or CS-17) are used for rotary friction under a specified load (such as 4.9 N or 9.8 N). After each certain number of revolutions, the machine is paused to observe whether the decorative pattern has been worn through to the substrate. The abrasion resistance grade is evaluated by the number of revolutions corresponding to the initial wear point (IP) and the final wear point (FP).

Internal bond strength determination: The specimen is cut to a specified size (such as 50 mm × 50 mm), and dedicated tensile fixtures are bonded to the upper and lower surfaces of the specimen with hot-melt adhesive. After the adhesive is cured, the specimen is installed on a universal material testing machine, and a tensile force perpendicular to the surface is applied at a constant rate until the specimen fails. The maximum load is recorded and the strength value per unit area is calculated, in MPa.

Dimensional stability testing (humidity treatment method): The specimen is conditioned under standard climate conditions (temperature 20±2 ℃, relative humidity 65±3%) until the mass is constant, and its initial dimensions are measured. It is then placed in a high-humidity environment (such as temperature 20±2 ℃, relative humidity 85±3%) and treated until the mass is constant again, and the dimensional change is measured. The stability is evaluated by calculating the change rate of length, width and thickness.

Surface stain resistance test: A variety of pollutants specified in the standard (such as acetone, coffee, shoe polish and blue ink) are selected, and about 1 mL of each is dropped or coated on the specimen surface. A watch glass is placed over it to prevent volatilization, and it is left at room temperature for a specified time (such as 16-24 hours). It is then wiped and cleaned with clean water, alcohol or other specified solvents, dried, and the stain marks and surface changes are observed under the specified lighting conditions.

Modulus of rupture and modulus of elasticity test (three-point bending method): A strip specimen (with length much greater than width) is supported on two fixed supports, with the distance between the two supports being more than 20 times the nominal thickness of the specimen. A vertical load is applied at the center of the span at a constant speed, and the maximum load at failure and the slope of the elastic deformation stage are recorded through the load-deflection curve, and the modulus of rupture and modulus of elasticity are calculated respectively.

Surface scratch resistance test: Common methods include the "Martindale method" and the "scratch tester method". The Martindale method is to carry out circular friction movement between the specimen and sandpaper of a specific grit under a certain pressure; the scratch tester method uses a scratch needle of a specified shape and hardness to scratch the specimen surface at a constant load and speed. After the test, the grade is evaluated by visual comparison or microscope measurement.

Testing Standards

Domestic Standards:

1. GB/T 18102-2020, Laminated floor covering

2. GB 18580-2025, Indoor decorating and refurbishing materials — Limit of formaldehyde emission of wood-based panels and finishing products

3. GB/T 17657-2022, Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels

4. GB/T 1931-2009, Method for determination of moisture content of wood

5. GB/T 1936.1-2009, Method of testing in bending strength of wood

International Standards:

1. ISO 12460-1, Determination of formaldehyde emission of wood-based panels — Part 1: 1 m³ chamber 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

Universal material testing machine: The core equipment for mechanical property testing, equipped with different fixtures and sensors, and can be used to determine internal bond strength, modulus of rupture, modulus of elasticity and surface bonding strength. Its high-precision load sensors and displacement sensors can accurately record the force and deformation during the test, and automatically calculate various strength indicators through software.

Taber abrasion testing machine: A classic equipment dedicated to surface abrasion resistance testing of materials such as floors and coatings. The main body includes a rotating platform, loading arms and abrasion wheels. By precisely controlling the rotational speed, loading weight and type of abrasion wheels, the effect of long-term foot wear can be simulated, and it is the standard instrument for evaluating the abrasion resistance revolutions of laminated floor.

Climate chamber for formaldehyde emission testing: Key equipment for determining formaldehyde by the chamber method. The internal environment of the chamber (temperature, relative humidity, air exchange rate and air flow velocity) can be precisely controlled by program, and the chamber material is made of inert material to avoid adsorbing formaldehyde. The equipped air sampling system can periodically and quantitatively collect the gas in the chamber for subsequent chemical analysis.

Spectrophotometer: Mainly used in the chemical analysis stage of formaldehyde emission testing. After sampling by the desiccator method or the chamber method, methods such as the acetylacetone method are used to develop the color of the collected formaldehyde absorption solution, and the absorbance of the solution is determined by a spectrophotometer at a specific wavelength (such as 412 nm), and then the accurate formaldehyde concentration is calculated according to the standard curve.

Constant temperature and humidity chamber: Used to provide a stable, controllable temperature and humidity environment for specimens, and is essential equipment for pretreatment and testing such as dimensional stability and equilibrium moisture content. It can precisely simulate various climate conditions from dry to humid, ensuring that the specimen reaches the specified equilibrium state before testing and ensuring the comparability and accuracy of test results.