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2 Vital Steps to Ensure Shrinking, Warping, Cupping or Checking of Wood

You would notice it on some wood on your furniture at home or the stacked wood for your woodworking projects. It usually starts with small cracks until it grows bigger and damages the entire piece. And sometimes, you think for no reason, the surface just suddenly becomes uneven. The splitting, swelling and other wood abnormalities happen because of certain changes in its environment.

By knowing the 2 vital steps to ensure shrinking, warping, cupping or checking of wood, as what it is called, you will become aware of why these things occur even on the new wood pieces, and thus you can figure out how to avoid them. This is why this list is personally important to me because these things take place naturally whether you want it to happen or not.

What is shrinking, warping, cupping and checking of wood?

Before tackling these vital steps that contribute to these conditions, you may want to know the definition and dynamics of each one first.

Shrinking, Warping, and Cupping of wood are conditions that happen when wood becomes deformed or uneven due to different moisture properties on the parts of the wood. It normally happens when frequent spilling of water in the floor, for example, as it would cause for that specific area to shrink, hence showing a concave shape. This is why sometimes you wonder that even with newly bought wood, you can see some areas being higher or bulging than the rest.

Warping is further subdivided into five types based on the image and shape that is formed on the wood namely, bow, kink, twist, cup, and crook.

Checking of wood, on the other hand, is like cracks that cause the separation of the wood. It is due to improper drying that causes internal stresses. Drying too quickly, like what usually occurs on the ends of the wood piece also causes splits or as in woodworking terms, the checks.

Aside from the fact that these affect the structure of the wood and damage the quality of it, all share common causes, which are dissected into these two vital steps.

1) Expose to Different Moisture Content

Changes in outside temperature and humidity would cause a varying reaction to the moisture content of the wood, hence causing some parts of it to bend or change in shape. Therefore, when a specific wood has a high level of moisture, it would shrink as it dries. Conversely, when its moisture content (MC) decreases, it will result in swelling. Hence, you can tell and would be able to determine the specific condition of the wood when this happens.

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Thus, the reason why your wood furniture would deform when always gets wet and exposed to too much sunlight. This is one struggle of wood workers and furniture sellers that it is advised to let the wood acclimate first before using or cutting it to pieces.

However, there are factors to consider that may influence the rate of changes in moisture content. The effect may be delayed or takes longer than normal. It includes:

  • the size of the wood piece
  • coating
  • different grain orientation​

2) Improper Handling and Storage

One of the steps to take to ensure the shrinking, warping, cupping and checking of wood is on how it is being transferred, handled, and stored, which could cause over-drying, for one and may greatly affect the equilibrium of its moisture content. When you pile and stack the wood, with some heavy weights and lying on an uneven and unstable foundation, can also cause the deformities and changes on its normal shape.

Storing it a place with improper ventilation and spacing is one factor, and at the same time when you place it in an open, wet and humid location as the wood will absorb a significant amount of moisture.

Hence, if you are in a business involving wood, it is apparent to control the outside environment and follow proper handling and storing procedures to ensure the quality.


Do you agree on the list of the vital causes and steps to undertake that will lead to these common problems we encounter with wood? Did you find this useful?

I make DIY wood projects, and most of our furniture at home are wood, hence knowing the steps that lead to damage and poor quality is something that we should be aware of. You may not probably have stacks of wood at home or run a furniture shop, but at least have a cabinet or a shelf that is made of wood, hence, either way, it is still important to know these things. You will not wonder anymore why there could be sudden cracks or deformities on your book shelf even without touching it.

And now that you know the vital steps, how do you go about avoiding it? I would love to know your thoughts about it. You can write it in the comment section below. And please share if you like and find this list helpful to you.

  • June 2, 2017
  • DIY