Seasoning of Timber Why is timber seasoned? Seasoning timber is essentially just to drain it of water which is called its moisture content. This can cause it to shrink but it helps to prevent warping, splitting, it will become lighter and stronger and it becomes easier to machine. List three reasons for seasoning timber. 1. To prevent shrinkage, splitting, checking and warping. 2. To achieve greater stiffness and strength. 3. To obtain a surface that will accept paint, polish or glue. What is Equilibrium moisture content and find a definition (EMC) The term “EMC” is an acronym for Equilibrium Moisture Content. The term is often used in relation to "hygroscopic" materials, such as wood. The term hygroscopic refers to a material that absorbs moisture from or releases moisture into the atmosphere until it achieves a balance with its surroundings. Air Seasoning Briefly describe air seasoning. Giving an advantage and disadvantage The timber is stacked on foundations to keep it off the ground. Strips of wood are placed between the layers of boards to allow air to circulate. Ends of boards may be painted to prevent drying and splitting. A waterproof covering is placed over the stack to protect the timber from the sun and the weather. Disadvantage: Air seasoning is slow, taking up to a year for a piece 25 mm thick and considerably longer for thicker pieces. Advantage: the timber produced is well suited to outdoor work. Timber stacked for air drying Kiln Seasoning Briefly describe kiln seasoning. Giving an advantage and disadvantage Kiln seasoning is done in a large oven-like structure in which air circulation, humidity and temperatures are controlled. The timber is stacked on the trucks in the same way as for air drying. The trucks are on rails so that they can be moved into the kiln. Care must be taken to see that the drying process while removing the free water is not too rapid Advantage: The moisture content can be reduced as per requirement. Disadvantage: This method is costly (though the space required is less). Solar Seasoning Briefly describe Solar seasoning. Giving an advantage and disadvantage Solar Kilns use collectors, fans and baffles to control air movement and temperature Advantages: Controlled environment using solar energy Faster drying with better control than air seasoning Less expensive than kiln seasoning Disadvantage: It needs a larger space for seasoning. In the table below summarize your research Type of Seasoning Advantages Disadvantages Natural the timber produced is well suited to outdoor work. Air seasoning is slow, taking up to a year for a piece 25 mm thick and considerably longer for thicker pieces. Kiln Kiln drying permits drying to the exact M.C. required, which may be much less Disadvantage: This method is costly (though the space required is less). than that of air dried timber. Solar Controlled environment It needs a larger space for using solar energy seasoning. Faster drying with better control than air seasoning Less expensive than kiln seasoning If you came across 2 pieces of timber in a timber yard, one was unseasoned and the other seasoned; how could you tell the difference? Unseasoned wood is wet and looks very new and fresh in the middle. The wood is lighter towards the edges of the log and the bark is tightly attached. To identify well seasoned wood, check the ends of the logs. If they are dark in colour and cracked, they are dry. Dry seasoned wood is lighter in weight than wet wood and makes a hollow sound when hitting two pieces together. If there is any green colour visible or bark is hard to peel, the log is not yet dry.
