Recently, a customer consulted us. He used a machine to bond boards and veneers. After the workers applied veneer glue and pressed them together through the machine, the product began to crack and bubble. He asked us the reasons and solutions for this situation. Based on our experience, we have summarized the following five reasons and shared them with you. We hope that it will be helpful to you.
Reason 1: Oily substances are mixed into the glue
When the veneer glue is applied or stored by workers, oily liquids or substances accidentally seep into it, and the veneer will bubble or crack during bonding. In this case, you need to replace the glue with a new one the first time and keep it properly in the future.
Reason 2: The pressure is small and the glue line is thick after bonding
When workers use machines to press leather, the machine’s pressurization pressure is insufficient, the glue and the veneer are not in good contact with the board, and the glue line is generally thicker after bonding, which can also cause cracking and blistering. Therefore, the problem can be solved by simply increasing the machine pressure appropriately.
Reason 3: The amount of veneer glue applied is too low
To save costs, many manufacturers do not apply the required amount of glue (150-180g/㎡). Too low an amount of glue will cause cracking and blistering. In this case, you only need to increase the amount of veneer glue according to the standard and the problem can be solved when a reasonable glue line is visible.
Reason 4: Insufficient hardener or expired active period
When the veneer you need to bond is thicker or requires stronger weather resistance, the glue needs to be properly added with a hardener. If the worker adds an insufficient proportion of hardener, or the glue and hardener are mixed but not used within the validity period, cracking will also occur. If this is the reason, you only need to reasonably mix the hardener MDI (100:5-8) and use it within the validity period (best within 30 minutes) to solve this problem.
Reason 5: There is an oily substance on the surface of the board
Many times, when the board is placed in the warehouse, it is easy to be infected with oily substances (such as paint, cleaning agents, etc.). If it is not detected during bonding, the glue cannot penetrate the board reasonably, and there may be cracking and foaming, resulting in fever. For this situation, it is necessary to clean or polish the board before pasting to solve this problem.
The above 5 reasons are the main reasons and solutions that lead to bubbling and cracking in the machine-painted veneer process after the product is painted. We hope that this will be helpful to everyone. If you have other questions, you can also consult us.
