Gluing
The veneer gluing process is the stage in which veneer sheets that have passed through the drying phase are coated with adhesive and prepared for the production of plywood panels. Gluing is a critical production stage that directly determines the inter-layer bonding strength and long-term durability of the panel.
Why Is Gluing So Important?
The quality of a plywood panel depends largely on the bonding strength between its layers. Insufficient or improper gluing leads to layer delamination, swelling, and structural weakening in the panel. The correct choice of adhesive, the correct application amount, and uniform distribution are decisive factors in terms of the panel’s moisture resistance, compressive strength, and long-lasting quality.
Types of Adhesives Used
Different types of adhesives are preferred in plywood production depending on the intended use. For panels intended for indoor use, urea formaldehyde (UF) adhesive is used. This adhesive is widely preferred in indoor furniture and cabinet production due to its economical cost and fast-curing properties. For applications that will be exposed to moisture and water, melamine formaldehyde (MF) or melamine urea formaldehyde (MUF) adhesives are preferred. For outdoor applications requiring high moisture resistance and panels used in the construction sector, phenol formaldehyde (PF) adhesive is used. This adhesive provides the highest water and moisture resistance.
Gluing Method
At Alesta Naturel facilities, the gluing process is carried out using adhesive spreader machines. Veneer sheets are passed between adhesive spreading rollers; an equal and uniform amount of adhesive is applied to both surfaces. The amount of adhesive is precisely set at 140–180 grams per square meter per single surface. This range is of critical importance for the adhesive to penetrate the veneer surface optimally and ensure strong bonding. Excess adhesive both increases costs and causes staining and irregularities on the panel surface, while insufficient adhesive reduces bonding quality.
Layer Assembly
After the gluing process, veneer sheets are stacked perpendicularly on top of each other. The wood grain direction of each sheet is positioned at a right angle to the previous one. This arrangement ensures that the plywood panel gains equal strength in every direction and increases the panel’s dimensional stability against moisture changes.
As Alesta Naturel, the adhesives we use in the gluing process are products that have been tested for compliance with European emission standards (E1 and E2). This ensures that the plywood panels we produce offer both high performance and reliability in terms of health and the environment.
For detailed information about our gluing process and products, you can contact our team.
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Veneer sheets are passed through adhesive spreading rollers and adhesive is applied equally to both surfaces.
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The adhesive type is selected according to the intended use: UF for indoor, PF for outdoor and construction applications.
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Sheets are arranged perpendicularly to give the panel equal strength in every direction.
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The adhesives used comply with European E1 and E2 emission standards.
F.A.Q
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What types of adhesives are used in plywood production?
Different adhesives are preferred depending on the intended use. Urea formaldehyde (UF) is used for indoor panels, melamine formaldehyde (MF or MUF) for humid environments, and phenol formaldehyde (PF) — which provides the highest water resistance — is used for outdoor and construction applications.
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How does the amount of adhesive affect panel quality?
Correct calibration of the adhesive amount is critical. Excess adhesive causes staining and irregularities on the panel surface, while insufficient adhesive reduces the bonding strength between layers and negatively affects the panel's durability.
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Why are the sheets arranged in a cross-grain direction?
Since wood fibers run in a single direction, panels with all layers arranged in the same direction are strong along that grain but weak in the perpendicular direction. Cross-grain arrangement provides equal strength in every direction and increases the panel's dimensional stability against moisture changes.
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Are Alesta Naturel adhesives safe for health and the environment?
Yes, all the adhesives we use are products tested for compliance with European emission standards E1 and E2. These standards limit formaldehyde emissions and ensure a healthy environment for indoor use.
