Multi-layer Solid Wood Board Testing

Multi-layer solid wood board testing is conducted in accordance with relevant standards and industry specifications. Scientific testing and analysis are performed on moisture content testing, formaldehyde emission testing, modulus of rupture testing, internal bond strength testing, surface bonding strength testing, and dimensional stability testing, objectively assessing the product quality grade. A detailed test report is issued within 7-10 working days, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Moisture content testing: Used to determine the moisture percentage inside the board and is a key indicator for controlling the dimensional stability of the board. The test result directly affects the risk of warping, cracking and subsequent processing performance of the board. Usually, in accordance with relevant national standards, the specimen is dried in an oven at a specified temperature to constant weight, and the percentage of mass loss is calculated.

Formaldehyde emission testing: This is a core indicator for evaluating the environmental safety of multi-layer solid wood boards. It mainly detects the concentration of free formaldehyde released by the board under specific conditions. Common methods include the perforation extraction method, the desiccator method and the chamber method. The result is directly related to indoor air quality and human health.

Modulus of rupture testing: A mechanical property indicator that measures the ability of the board to resist bending deformation. The test simulates the state in which the board bears static loads in actual use. A three-point bending testing machine is used to load the specimen until failure, and the maximum failure load is recorded to evaluate the structural load-bearing capacity of the board.

Internal bond strength testing: Also known as bonding strength, it is used to evaluate the quality of the bonding between the inner veneer layers of the board. A tensile testing machine applies tension perpendicular to the board surface, and the maximum stress at which the adhesive layer fails is measured, reflecting the overall structural stability of the board.

Surface bonding strength testing: Specifically targets the bonding force between the surface layer of the board (such as decorative veneer and impregnated paper) and the substrate. Dedicated fixtures apply tension perpendicular to the surface covering layer to test the force required to peel or pull it off, serving as an important basis for judging the quality of the surface lamination.

Dimensional stability testing: Mainly tests the dimensional change rate of the board under changes in temperature and humidity, including water absorption thickness swelling. By simulating different environmental humidity conditions, the change in thickness or length of the board after moisture absorption or desorption is measured to evaluate its resistance to wet swelling and dry shrinkage.

Screw holding power testing: An indicator for evaluating the ability of the board to hold fasteners (such as screws). A standard screw is driven into a pre-drilled hole in the board, and a tensile testing machine pulls the screw out along the axial direction to record the maximum pull-out force. This indicator is directly related to the assembly firmness and durability of furniture or wood products.

Testing Scope

Substrate testing: Mainly targets the core and inner layers of the multi-layer solid wood board, focusing on veneer quality, joint gaps, core material type and the presence of defects such as decay and insect damage. The substrate is the foundation that determines the structural strength and stability of the board, and its testing is the primary link in quality control.

Adhesive performance testing: Adhesives are a key factor affecting the environmental and mechanical properties of the board. The testing scope includes the physicochemical properties of the adhesive itself, as well as its water resistance and heat aging resistance in the service environment after curing, to ensure that the adhesive layer maintains sufficient bonding force throughout its service life.

Surface decorative layer testing: For laminated multi-layer solid wood boards, tests the performance of the surface decorative materials (such as solid wood veneer, melamine-impregnated paper and PVC film), including abrasion resistance, scratch resistance, color fastness to light, stain resistance and surface bonding strength.

Environmental safety performance testing: In addition to formaldehyde emission, the testing scope also covers other potentially hazardous substances, such as total volatile organic compound (TVOC) emission and heavy metal content (lead, cadmium, chromium and mercury), to ensure the product meets relevant environmental regulations.

Physical and mechanical property testing: Covers other mechanical indicators in addition to modulus of rupture and screw holding power, such as modulus of elasticity, surface hardness and impact resistance. These indicators comprehensively reflect the performance of the board under different loading conditions and are important references for engineering design.

Flame retardancy testing: For applications with special fire protection requirements (such as public buildings), the combustion performance of the board needs to be tested, including flame retardancy grade, oxygen index and smoke density, to evaluate its fire safety.

Comprehensive performance testing of finished boards: The board is treated as a final product for comprehensive evaluation of appearance quality (such as warpage, waviness, color difference and surface defects), dimensional specification deviation and overall durability.

Testing Methods

Chamber method (ENV 717-1, GB/T 17657): The arbitration method for formaldehyde emission testing. A board sample of specified area is placed in a large climate chamber with constant temperature, humidity and air exchange rate. After the formaldehyde concentration in the chamber air reaches equilibrium, air samples are collected for analysis. This method most closely reflects the release state of the board in a real indoor environment.

Desiccator method (GB/T 17657): A common method for formaldehyde emission testing. The specimen is placed in a desiccator containing distilled water at the bottom, sealed at a constant temperature for a certain time, and the formaldehyde released by the board is absorbed by the absorption solution, which is then measured with a spectrophotometer to determine the formaldehyde content.

Perforation extraction method (ISO 12460-1, GB/T 17657): A method for determining the extractable formaldehyde content of the board. After the specimen is crushed, it is heated and extracted in toluene solvent through a perforator so that the formaldehyde is completely released from the board and dissolved in water, and the formaldehyde content in the aqueous solution is determined. This method measures the potential formaldehyde content inside the board.

Three-point bending test method (GB/T 17657, ASTM D1037): The standard test method for modulus of rupture and modulus of elasticity. A strip specimen is simply supported at both ends, and a concentrated load is applied at a constant rate at the center point of the span until the specimen fails. The relevant mechanical parameters are calculated from the load-displacement curve.

Internal bond strength test method: Dedicated fixtures are used to apply tension uniformly to metal blocks bonded to both faces of the specimen, so that the tension acts perpendicular to the entire board surface and is loaded at a constant speed until the adhesive layer fails. The maximum tensile force is recorded and the strength value per unit area is calculated.

Moisture content determination - oven-drying method (GB/T 1931): A representative specimen is weighed and then dried in a drying oven at a specified temperature to constant weight and weighed again. The moisture content is calculated from the percentage of the mass difference before and after drying relative to the mass after drying. This is the most classic and accurate determination method.

Water absorption thickness swelling determination method: A test that measures the thickness change of the specimen before and after water immersion. The initial thickness at the center point of the specimen is first measured, then it is completely immersed in water at a specified temperature for a specified time, removed, surface moisture wiped off, and the thickness is measured again to calculate the percentage increase in thickness.

Testing Standards

Domestic Standards:

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

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

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

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

5. GB/T 4823-2013, Defects in sawn timber

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 mechanical testing machine: The core equipment for almost all mechanical property tests such as modulus of rupture, internal bond strength, modulus of elasticity and screw holding power. Equipped with high-precision sensors and a computer control system, it can precisely control the loading rate and collect and process load, displacement and other data in real time.

Formaldehyde emission testing climate chamber: A large environmental simulation chamber that can precisely control the internal temperature, relative humidity, air exchange rate and background formaldehyde concentration. Equipped with a professional air sampling and circulation system, it is used to simulate a real indoor environment and is key equipment for arbitration testing of formaldehyde emission.

Spectrophotometer: The main instrument for quantitative analysis of formaldehyde content. Based on the Lambert-Beer law, it measures the absorbance of the product formed by the reaction of formaldehyde with a specific chromogenic agent at a specific wavelength to calculate the precise formaldehyde concentration in the sample. It is widely used in the desiccator method, the perforation extraction method and other tests.

Constant temperature and humidity drying oven: Used for moisture content determination and some pretreatment tests. It can provide a stable and uniform heating environment, and some models have dehumidification functions to simulate specific temperature and humidity conditions. It is essential equipment for material drying, curing, aging and other treatment processes.

Blast drying oven: Complements the function of the constant temperature and humidity oven and is mainly used for occasions requiring rapid high-temperature drying, such as the drying-to-constant-weight step in moisture content determination. Through forced convection, the temperature inside the oven is more uniform and the drying efficiency is higher.

Precision thickness gauge / micrometer: Used to measure board thickness, water absorption thickness swelling and other dimensional parameters. High measurement accuracy is required, usually accurate to 0.01 mm, and the measuring head must have a specified contact area and pressure to ensure the accuracy and comparability of the measurement results.

Electronic balance: A high-precision weighing device used for specimen mass and moisture content calculations. In moisture content testing, its accuracy needs to reach 0.01 g or even higher to ensure the accuracy of the final calculation results. It is a basic and key measuring instrument in the laboratory.