Wood: Seasoning, Cutting, & Defects | Pass the ARE 5.0

Summary

This video delves into wood seasoning, cutting techniques, and common manufacturing defects. It explains why wood needs to be dried before use, highlighting two seasoning methods: kiln drying and air drying. The video also covers the differences between plane, quarter, and rift sawing techniques, emphasizing how each method affects wood's stability and appearance. Additionally, it identifies common manufacturing defects like checks, splits, wanes, and warps, explaining how these can impact wood quality. Overall, it's an informative guide for anyone working with or learning about lumber.

Takeaways

• 🌳 Green lumber contains a lot of water and is not suitable for construction until it's seasoned.
• 🔥 Seasoning involves drying out wood to reduce moisture content to 19% or less, preventing shrinkage and warping.
• 🏭 Kiln drying and air drying are the two methods of seasoning wood, with kiln drying being faster and more effective.
• 📏 Seasoned lumber is stronger, stiffer, lighter, and more resistant to decay and insects than green lumber.
• 📌 Proper seasoning improves nail holding power and the ability of wood to hold paint.
• 🏷 Look for labels like 'KD' for kiln-dried or 'SD' for air-dried to identify seasoned lumber.
• ✂️ There are three types of wood cuts: plain sawing, quarter sawing, and rift sawing, each with different characteristics and uses.
• 🌀 Plain sawn wood has a cathedral grain pattern and is the most common and cheapest method, but may twist or cup.
• 📏 Quarter sawn wood is more stable and shows a linear grain pattern, with less tendency to twist, warp, or cup.
• 💰 Rift sawn wood is the most expensive and wasteful to produce but offers the most consistent and beautiful grain.
• ⚒ Manufacturing defects such as checks, splits, wings, and warps can occur in wood due to improper seasoning or processing.

Q & A

What is the difference between green wood and seasoned wood?

Green wood is wood that is freshly cut from a living tree and contains a lot of water. Seasoned wood, on the other hand, has been dried to reduce its moisture content to 19 percent or less, making it suitable for construction and minimizing future shrinkage.

Why is it important to season lumber before construction?

Seasoning lumber is important because it reduces the moisture content, which in turn minimizes the tendency of the wood to shrink, warp, and twist. Seasoned lumber is stronger, stiffer, lighter, and more resistant to decay, insects, and mold. It also has better nail holding power and a greater ability to hold paint.

What are the two methods of seasoning wood?

The two methods of seasoning wood are kiln drying and air drying. Kiln drying involves placing the wood in a large kiln and heating it to draw out moisture, while air drying involves leaving the wood in a cool, clean, dry, and shady space to slowly lose its moisture.

How does kiln drying compare to air drying in terms of time and moisture content?

Kiln drying can reduce the moisture content of the wood to under 10 percent in just a few days, whereas air drying typically only reduces the moisture content to 10 to 20 percent and takes months to do so.

What do the markings 'KD', 'SD', 'S GN', and 'S GRN' indicate on lumber?

The marking 'KD' indicates kiln-dried lumber, 'SD' indicates air-dried lumber, 'S GN' or 'S GRN' indicates green lumber. These markings are important to know so that the correct lumber is purchased for the job.

What are the three types of wood cutting methods mentioned in the script?

The three types of wood cutting methods mentioned are plain sawing, quarter sawing, and rift sawing. Each method affects the look of the wood, its dimensional stability, and its resistance to warping.

Which wood cutting method is the most common and cheapest, and what is its characteristic grain pattern?

Plain sawing is the most common and cheapest method. It results in a distinct Cathedral grain pattern and often a raised grain.

What is quarter sawing and how does it affect the wood's stability?

Quarter sawing is a method where a log is cut into four quarters and then each quarter is plainsawed at an angle. This results in a linear grain pattern and makes the lumber more dimensionally stable with almost no twisting, warping, or cupping.

Why is rift sawing considered the most wasteful and expensive cutting method?

Rift sawing is considered the most wasteful and expensive because it leaves triangles of waste between each board. However, it provides the most straight-lined grain and is the most reliable and beautiful cut available.

What are the four main manufacturing defects that can occur in wood?

The four main manufacturing defects that can occur in wood are checks, splits, wings, and warps. Checks are lengthwise separations caused by seasoning, splits are lengthwise separations extending from one face to the other, wings indicate a lack of wood on the edge or corner, and warps are distortions due to shrinkage.

What are the four types of warpage that can occur in wood?

The four types of warpage that can occur in wood are bowing, crooking, cupping, and twisting. These are distortions that affect the shape and flatness of the wood.