Unseasoned timber, also known as green timber, refers to wood that has not yet dried thoroughly enough to be considered seasoned. It contains a high level of natural moisture remaining from the tree.
Key Characteristics of Unseasoned Timber
The defining characteristic of unseasoned timber is its high moisture content. According to the provided information:
- The moisture content of unseasoned timber can range significantly, from as low as 25% to as high as 100%. This means that the weight of the water in the timber can be anywhere from a quarter to the entire weight of the dry wood itself.
This high moisture level is a direct result of the timber not undergoing a proper drying process (either air-drying or kiln-drying) to reach a stable moisture equilibrium with its surrounding environment.
Unseasoned vs. Seasoned Timber: A Moisture Comparison
Understanding unseasoned timber is often easiest when contrasted with its seasoned counterpart. Seasoned timber has been dried to a much lower, more stable moisture level, making it suitable for construction and other uses where dimensional stability is critical.
Here's a simple comparison based on moisture content:
| Timber Type | Moisture Content Range | Notes |
|---|---|---|
| Unseasoned | 25% to 100% | High moisture; "green timber" |
| Seasoned | 10% to 15% | Much lower; stable (e.g., for South-East Queensland) |
As the table shows, seasoned timber has a dramatically lower moisture content than unseasoned timber. This difference is fundamental to how the wood behaves.
Practical Implications of Using Unseasoned Timber
While sometimes used for specific applications (like fence posts buried in the ground), unseasoned timber is generally avoided for construction or fine woodworking due to its instability. The high moisture content can lead to:
- Significant Shrinkage: As the wood naturally dries over time, it will shrink considerably, potentially causing structures to move or crack.
- Warping and Checking: Uneven drying can cause the wood to twist, cup, or split (check).
- Increased Weight: The high water content makes the timber much heavier and harder to handle.
- Finishing Issues: Paints and finishes do not adhere well to wet wood.
- Higher Risk of Mold and Fungi: The moisture provides an ideal environment for biological growth before adequate drying occurs.
Therefore, the "seasoning" process, which reduces moisture to the levels seen in seasoned timber (like 10-15%), is crucial for producing stable and durable lumber suitable for most building purposes.
