Recently, several friends have been asking about what "raw material," "old material," and "aged material" mean in the context of yew wood. It seems that some newcomers to this topic are still confused about these key categories. In this article, I'll clarify these terms and provide a detailed explanation for those who are interested.
Some of the content in this text is based on information from other authors. I apologize for not being able to list all sources individually. Thank you for your understanding.
Before diving into the three types of materials—raw, old, and aged—it's important to first understand the basic structure of wood. This foundational knowledge will help you better grasp the terminology I'll be using next.
The Bark, Sapwood, and Core Material of Wood
In the xylem, the outermost layer near the bark (usually lighter in color) is known as the sapwood. This part is alive and contains living cells. The core material, located between the sapwood and the center of the tree, is darker in color and consists of dead cells that no longer function. Understanding this distinction is crucial when discussing different types of wood materials.
As shown below:
Raw Material
As the name suggests, raw material refers to freshly cut or unprocessed wood. The defining feature is the presence of bark (sometimes stripped) and sapwood, which is the white layer we often refer to as the "white skin." This type of material is typically moist, sometimes even with leaves still attached. It’s generally not preferred for long-term use due to its instability and tendency to crack over time.
Here’s an example:
This image, found on Baidu, clearly shows the bark and sapwood, both of which fall under the category of raw material. To summarize: raw material is fresh, alive, and full of moisture.
Why Raw Material Cracks
Thuja wood contains polar hydroxyl groups, which cause expansion and contraction when moisture is absorbed or released. This process can lead to uneven shrinkage or swelling, especially along the grain. As a result, the wood may develop cracks or bends over time.
Related reading: Secret wood with English, numbers and other symbols
Chen Huan Material
Before discussing "old material," it's essential to first understand "Chen Huan" material, as it provides a clearer foundation for the discussion. Chen Huan material refers to the parts of thuja wood that have completely weathered and decayed on cliffs, leaving only the core material behind. Some people call it "weathered material," others "de-agglomerated," or "relic material."
As shown below:
Notice that there is no bark or sapwood left. What remains is the gully, symbolizing the passage of time and the resilience of nature. This is the kind of material that many appreciate for its character and history.
Old Material
After the aging process, we come to "old material." By definition, old material refers to the stage after the thuja has died on the cliff (note that this condition is specific to cliff environments) but before the bark and sapwood have fully weathered away. In other words, old material is the stage where the bark and sapwood are still present but beginning to show signs of decay.
Here’s an example:
The period during which old material exists can be quite long. One friend once shared a story about a dead cypress tree on a cliff near his house. His father had seen the tree die when he was young, and now, in his 40s, he discovered that the sapwood (the white skin) was still intact. This shows how slow the decay of sapwood can be—often taking decades or even longer.
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