Fushen woodworking glue! This article will help you understand the causes and solutions of cracks in hand-pasted wood veneer

Hand-pasting wood veneer is a craft that requires meticulous operation. However, in the actual process, the problem of wood veneer cracking often troubles the artisans. Analyzing from the two key aspects of glue and operation techniques can help us identify the root cause of the problem and improve the quality of veneering. ​

I. Reasons at the glue level

(1) Improper selection of glue

The requirements for glue vary depending on the material of the wood veneer and the different application scenarios. If the glue does not match the material of the wood veneer, cracking problems are likely to occur. For instance, when using ordinary white latex glue to bond hard wood veneer with a relatively high density, due to its limited bonding strength, it is difficult to firmly adhere the wood veneer to the base material. During subsequent use, the wood veneer may crack under the influence of external forces or environmental factors. In addition, some low-quality adhesives have unstable components, poor water resistance and weather resistance. When the humidity changes or the temperature fluctuates, the adhesive layer is prone to lose its stickiness, causing the wood veneer to separate from the base material and subsequently leading to cracking. ​

(2) Uneven application of glue

The evenness of the glue application directly affects the bonding effect. If too little glue is applied, the bonding force between the wood veneer and the base material will be insufficient, and a firm connection cannot be formed. Under the influence of external factors, the wood veneer is very likely to crack. Applying too much not only leads to the waste of glue but also causes the excess glue to overflow and contaminate the surface of the wood veneer. At the same time, excessive glue will generate a large shrinkage force during the drying process, pulling the wood veneer and causing it to crack. In addition, if there is local accumulation or missed application of glue during application, it will also cause inconsistent bonding strength and uneven force distribution among different parts of the wood veneer, thereby leading to cracking. ​

(3) The glue is not dried thoroughly

The drying process of the glue is crucial to the bonding effect of the wood veneer. If the glue is not completely dry before subsequent processing or use, the bonding strength of the glue layer has not yet reached the optimal state. At this time, the wood veneer is prone to cracking due to external forces. For instance, in a low-temperature and high-humidity environment, the drying speed of the glue will significantly slow down. If the environmental factors are not fully considered and the next step is carried out too early, the risk of wood veneer cracking will be greatly increased. In addition, the drying time and conditions for different types of glue also vary. If the drying process is not carried out in accordance with the glue's usage instructions, it may also lead to insufficient drying of the glue, causing the wood veneer to crack. ​

Second, reasons at the level of operational techniques

(1) Improper treatment of the substrate

Before applying wood veneer, the surface treatment of the base material is of vital importance. If the surface of the substrate is uneven, dusty, oily or moist, it will seriously affect the bonding effect between the glue and the substrate. An uneven surface will create gaps between the wood veneer and the base material, resulting in a weak bond. Dust and oil stains can prevent the glue from fully contacting the substrate and reduce the bonding force. Moisture, on the other hand, will dilute the glue and affect its performance. Meanwhile, during the drying process, the evaporation of moisture may also cause the wood veneer to deform and crack. In addition, if the base material itself has problems such as deformation and warping, after attaching the wood veneer, as the stress of the wood is released, it is also easy for the wood veneer to crack. ​

(2) The cutting and splicing of wood veneer are unreasonable

The cutting size and splicing method of wood veneer have a significant impact on the effect of veneering. When cutting wood veneer, if the size is inaccurate, either too large or too small, it will cause the wood veneer and the base material to not fit perfectly, which is prone to stress concentration and cracking. During the process of wood veneer splicing, if the splicing seams are not properly handled, such as being too wide, having inaccurate splicing angles, or not undergoing special treatment at the splicing points, the splicing areas will become weak links for wood veneer cracking. In addition, when wood veneers of different textures and directions are joined together, if the characteristics of the wood are not taken into account, cracking may also occur due to inconsistent shrinkage and expansion of the wood.

(3) Improper pressurization methods and pressure control

During the process of applying wood veneer, applying pressure is a crucial step to ensure that the wood veneer adheres closely to the base material. If the pressurization method is unreasonable, such as uneven pressure distribution, it will cause different bonding effects in various parts of the wood veneer, and the parts subjected to greater force are prone to deformation and cracking. If the pressure is too low, the wood veneer and the base material cannot bond fully, which is prone to hollowing and delamination, and eventually leads to cracking. However, excessive pressure may damage the surface of the wood veneer, causing problems such as indentations and cracks. In addition, insufficient or excessive pressurization time can also affect the bonding effect. If the time is insufficient, the glue will not fully cure and the bonding will not be firm. If the time is too long, it may cause the wood veneer to deform due to excessive pressure. ​

(4) Inadequate post-processing and maintenance

After the wood veneer is applied, the subsequent treatment and maintenance are equally important. If the surface of the veneer is not properly ground and polished, it will be uneven and prone to stress concentration, increasing the risk of cracking. During use, if proper maintenance is not carried out, such as frequent contact with water, high-temperature environments, or exposure to external impacts and friction, it will accelerate the damage of the wood veneer, leading to cracking. For instance, if furniture with wood veneer is placed in direct sunlight, the wood veneer will lose water and crack due to excessive temperature. Wiping the surface of the wood veneer with a damp cloth for a long time will cause the glue to become damp and lose its stickiness, leading to cracking of the wood veneer.

Iii. Solutions and Approaches

Choose Fushen quick-drying glue

When pasting wood veneer by hand, it is recommended to use professional wood veneer glue. For instance, there are Fushen veneer adhesives such as GW-6565, GW-6566A, and GW-5001, as well as heat-pressed wood veneer adhesives like GW-6528, GW-6525A, and GW-6526A, etc. Fushen Woodworking Adhesive has been dedicated to wood veneer adhesive for 20 years and holds a leading position in the industry.

Fushen's veneer adhesives, such as GW-6565 or 6566A, are fast-drying types that can significantly reduce ironing time and lower the risk of cracking caused by repeated ironing and water loss of the wood veneer. In case of bubbling, it can be repaired by ironing. Fushen's veneer adhesives are recommended for wood veneers ranging from 20 to 120 microns.

Choose professional wood veneer glue tools

Nowadays, many veneer factories choose household irons, which are extremely hot and can easily crack the wood veneer or cause it to lose moisture quickly, leading to the wood veneer cracking. Here we recommend the professional GW-1211 irregular-shaped wood veneer iron from Fushen, which is specifically designed for manual wood veneer application on furniture, wooden doors, decorations, display cabinets, etc.

It can heat flat surfaces, wire grooves, right-angle edges, concave arc surfaces, etc. Moreover, there are four temperature Settings that can be adjusted to prevent the temperature from being too high. Hand-pasted wood veneer is highly recommended for this professional iron.

Fushen Woodworking Adhesive is a brand of woodworking adhesives under Guangdong Fushen Chemical Co., LTD. It covers water-based environmentally friendly single-component, high-performance wood veneer adhesives, panel gluing adhesives, assembly adhesives, pressing board adhesives, etc., integrating R&D, production and sales.

Fushen was founded in 2005 and has been dedicated to the field of woodworking adhesives for many years. It is committed to developing environmentally friendly and high-performance adhesive products to catch up with international professional standards and is hailed by the wood products industry as "China's Expert in wood veneer adhesives".