What Is Wood Movement And How Can It Affect Your Woodworking Projects?
When you work with wood, it's important to understand the different ways that it can move. Wood movement isn't always easy to predict, and if you're not prepared for it, your woodworking projects can be ruined. In this article, we'll discuss what wood movement is, why it happens, and how you can compensate for it in each stage of your process.
What Is Wood Movement?
Wood movement refers to the way that wood changes shape in response to changes in temperature and humidity. This can happen both while the wood is being processed (during kiln-drying, for example) and after it has been made into a finished product.
Why Does Wood Move?
Wood is made up of cells, and the cell walls are held together by a substance called lignin. Lignin is what gives wood its strength and rigidity. However, lignin is also affected by changes in temperature and humidity. When the weather gets warmer and more humid, the lignin expands, and the wood swells. Conversely, when the weather gets cooler and drier, the lignin contracts, and the wood shrinks. This expansion and contraction of the wood are what causes wood movement.
How Wood Usually Moves
Width-Wise Is The Problem
The wood expands most width-wise and least thickness-wise. That's why woodworking joints that are glued together while the wood is dry can become loose as the wood expands. Pieces will start to push each other out of the way. If you think of the way wood planks are laid out in most of your projects, that can be a big issue. If two boards are mounted flush next to each other and start to swell width-wise, they need to go somewhere. If they're mounted too tight, they're going to start buckling or popping out of your project.
Swelling Outward
Outward swelling is one reason why woodworking projects start to warp. That can cause big gaps between boards, or make already mounted boards start to pull away from each other. It can also cause wood to split along the grain if it's under too much stress.
Warping And Buckling
Lastly, wood can totally change shape due to weather or humidity. A board that was straight when you started your project can pop up and twist very quickly. This is called warping, and it's one of the most frustrating things that can happen to a woodworker. Warping can cause all sorts of problems, from making it difficult to mount pieces flush against each other, to causing your project to completely fall apart. Buckling is when wood bends or curls due to changes in humidity. It's similar to warping, but it can happen even if the wood is already mounted in your project.
How Can Wood Movement Affect Your Woodworking Projects?
Wood movement can cause all sorts of problems in woodworking projects. If you're not careful, wood movement can make your joints loosen, warp your wood, and crack your paint or finish. Futhermore, wood that has been improperly dried is more likely to experience wood movement, which can make your project fail even if you've done everything else right.
How To Prevent Wood Movement
The best way to prevent wood movement is to use wood that has been properly kiln-dried. Kiln-drying removes the moisture from the wood slowly and evenly, which prevents the wood from warping or cracking. You can also use wood that has been air-dried, but it's more difficult to find wood that has been air-dried to the proper moisture content. Another way to prevent wood movement is to use a wood species that is less likely to move, such as cherry or walnut. There are also some woodworking techniques that can help to minimize wood movement, such as using floating panels or breadboard ends. Finally, you can use a wood stabilizer, which is a product that you apply to the wood to help prevent wood movement.
How To Compensate For Wood Movement
If you're not able to prevent wood movement completely, there are some woodworking techniques that can help you to compensate for it. For example, you can use a spline joint instead of a butt joint to allow for wood movement. You can also use a loose tenon joint, which is a type of mortise and tenon joint that allows the wood to move without affecting the strength of the joint. Use wood screws, rather than nails, to assemble your project. This will allow the wood to expand and contract without affecting the joints. You can also use a wood filler or putty to fill in any cracks that may form as a result of wood movement.
Wood Movement FAQs
What is wood grain?
Wood grain is the direction, size, and shape of the wood cells.
How does wood grain effect wood movement?
The grain of the wood affects the way that the wood expands and contracts. For example, wood that has a straight grain will expand and contract more evenly than wood that has a wavy grain. As a result, wood with a straight grain is less likely to warp or crack.
What are the different types of wood grain?
There are three main types of wood grain: straight, wavy, and curly.
How does wood moisture content affect wood movement?
The moisture content of the wood affects how much the wood will expand and contract. Wood that has a high moisture content will expand more than wood that has a low moisture content.
What is the difference between wood movement and wood shrinkage?
Wood movement is the changes in shape and size that wood undergoes as it absorbs or releases moisture. Wood shrinkage is the changes in shape and size that wood undergoes as it dries.
Wood Movement | Final Thoughts
Wood movement is a natural process that occurs as wood absorbs or releases moisture. While you can't completely prevent wood movement, there are some woodworking techniques that can help you to minimize its effects. No matter how you choose to handle wood movement, the most important thing is that you keep it in mind. If you plan for wood movement from the very beginning of a project, you'll be ready when something doesn't go quite as expected.