Drying Veneers will make the size of the wood stable, free from pests, easy storage, and the finishing and processing process of the plywood sheets will also achieve higher quality. Good veneer drying practice is essential for making good quality plywood sheets. In particular, the drying of veneers will reduce its weight, thereby reducing transportation costs.
Problems with Wet Veneers
The over amount of moisture in the veneer can affect the spread of glue on the veneer surface of plywood sheets. Wrong material can cause blister, glue penetration, glue peeling, etc.
High moisture veneer is not suitable for hot-press process of plywood manufacturing. It will prolong the hot press time and discount the quality of wood panels.
There are two popular veneer drying methods: air-drying and forced drying.
Air-drying is a natural way of drying veneers. The sun provides energy (heat) for the evaporation of water in the veneers.
Using the air-drying method, veneers can be dried to a moisture content of 12 – 20% depending on weather conditions. The drying time can vary greatly from 10-30 days. This depends on the species and the size of the veneers.
2. Forced drying
Veneers, before being used for making plywood sheets or for some other use … it is usually dried to the required moisture content. In order to achieve this goal quickly and accurately, the veneers are dried in a kiln. Unlike the drying process, the temperature, relative humidity, and air circulation in the kiln are controlled during the drying process.
The temperature in the drying process can be up to 100 degrees Celsius. However, drying with high temperature is not common because it is difficult to limit defects that araise in the drying process.
Advantages And Disadvantages Of Two Method
Compared to drying by forced drying, air-drying requires little investment and no energy costs. However, air-drying has the following disadvantages:
- Long drying time.
- Veneers cannot be dried to moisture below 12%. Lower humidity is often required for products exported to countries with mild climates.
- Need a large area for stacking and drying.
2. Forced drying
The advantages of drying wood by forced drying method:
- The drying process is controlled, and defects are limited
- Achieve lower humidity compared to air-drying
- The drying time is shorter than that of air-drying
- The kiln is used for many different types of wood
- Achieve the exact humidity required
- The veneers fungus pests are destroyed during the drying process
Disadvantages of wood drying by forced drying:
- Requires bigger investment than air-drying
- Required cost for energy
- It is required that the operator must have skills in oven operation and maintenance.
Currently, most factories in developed countries are usually natural methods (air-drying) to dry in order to save energy costs.
Understanding these limitations, FOMEX’s factories have invested in machinery and equipment for forced drying. We aim to have a long-term business strategy, ensuring stable quality in plywood sheets. We hope we can contribute to bringing Vietnam’s plywood to reach extreme quality.