What is End-Checking in Wood – Causes & Prevention Tips

One of the many things that can befall wood is something that is known as checking or end checking.

An end check is the name of the process when the wood begins to separate around its growth rings.

This is a natural and normal process that occurs when the force that is drying the wood is greater than the strength of the wood itself.

This force occurs most commonly around the outer edges of the wood that surround the core, which tends to be moister. It can happen to any species of wood, from maple to mahogany.

Read on to understand what causes this process, how to prevent it, and how to stop it from spreading.

In This Article We Will Cover:

What Causes End Checks?

An end check specifically is when a spit or crack occurs at the end of the board. This occurs since the outer edges of the wood dry at a much faster rate than the inner portions of the board.

It occurs when the stress from quick-drying becomes more than the board can accommodate.

While seasoning is usually the reason for this, drying and other environmental issues can cause it as well.

It’s nearly impossible to entirely prevent checking, but you can work to keep the checks in balance as much as possible.

Wood Checking Prevention Tips

Though many people like to recommend sealing or painting the end grain, that is not the only way to do it.

On top of that, the process is an expensive one and doesn’t ultimately end up being as effective as you’d like. Instead, you can follow the steps below for the best results:

Check the moisture content of the wood using a moisture meter. If the meter doesn’t come with an adjustment feature, be sure to factor manual adjustment into what you calculate.

If the wood has an overabundance of moisture, you can stack it on stickers. Allow at least a .25-inch gap between the boards to allow for air to flow through.

Plastic wrap the ends to keep the grain well covered.

Wait until the wood has equalized before removing them from the sticks. Using a moisture meter to get a reading on different parts of the board is the best way to ensure the board is properly equalized.

You can accelerate the dissipation rate of the moisture by slowing down the rate at the end of the boards this way.

Any movement in the lumber will occur simultaneously to ensure there is minimal internal stress.

Through this process, end checking is greatly reduced.

From time to time, there may be a major issue with the moisture level in the wood. When this happens, it may benefit you to put the wood back in a kiln.

Why are Imported Woods Prone to Checking?

There are various reasons why imported woods are particularly prone to end-checking as opposed to domestic wood.

a) Species

Firstly, certain wood species are more likely to check than others. This is because wood is likely to check along with the rays.

Woods that have large rays, such as North American Beech and White Oak, have a greater likelihood of checking than woods with smaller rays, such as American Cherry or White Hard Maple.

When it comes to imported woods, Brazilian and Jatoba woods are more likely to check than Genuine Mahogany, for instance.

b) Board size

A lot of imported woods are sawn into large sizes. For example, you’ll often find 15-inch-wide mahogany boards.

Sometimes, this can result in the board not being able to consistently equalize, causing it to develop splits, twists, and checks.

The edges of a board may dry out faster due to exposure to wind while the core of the board contains a higher content of moisture.

In boards of smaller sizes, the changes in moisture content across the various parts of the board are usually minimal and aren’t enough to generate check-causing stress.

c) Kiln drying

The method and quality of kiln drying can affect the stability of the wood, therefore, increasing the chance of checking.

Other Different Types of Wood Cracks to Be Aware of

Since wood is an organic material, cracking and end-checking is a normal process.

However, there are certain kinds of splits and cracks in wood to be aware of. These include:

1- Shakes

Shakes can occur when wood separates lengthwise along the grain.

You might notice shakes that only run halfway down the wood, but some go completely through the wood’s length and are known as “through shakes.”

This kind of cracking is certainly a natural process that occurs while the tree is still growing. Bacteria that get into the roots instead of the stem will cause shakes.

2- Splits

Gaps that occur in an adjoining surface are known as splits.

They are caused by a force that tears apart the cells of the wood, and they usually occur during the drying process.

3- Roller splits

These are also caused by a force that pushes apart the cells of the wood.

They often occur when a warped piece of wood is pushed through a flattening machine.

This will generate a split where the board is forced against its shape.

4- End splits

This kind of split is caused by natural stresses that a tree might experience while growing instead of manmade causes.

This includes excessive snow, high winds, or stress in growth.

If you leave these cracks untreated, they may begin to spread. This is true especially if you live somewhere that is extremely humid or extremely dry.

Untreated cracks can cause boards to become unusable or to separate or warp.

What you’ll need to do to stop cracks from continuing to spread will depend on the method you are using to handle it.

How to Stop the Wood Cracks and Checks from Spreading?

There are four ways to effectively deal with a crack: replace it, remove it, patch it or fill it.

Below are some benefits and drawbacks of each of these methods:

1- Replace the Cracked Wood

If the crack occurs further from the edge of the board or in a piece of wood that is finished, it might not be feasible to take it off entirely.

For this kind of crack, you can fill it with a bowtie or inlay after routing it out.

If the crack runs all the way down into the board, you will have to inlay both sides of it.

The PROS

Completely avoids warping
Offers a nice finish to the existing piece

The CONS

Takes more time and effort than other methods
Requires you to have router skills and knowledge
Requires you to have various additional tools like chisels

2- Remove the Cracked Wood

If you have wood that is cracking along the edge, there is a chance you can just remove it.

Mark the cut-line a few inches away from the edge of the crack, and keep in mind that it might extend further than the surface where it cannot be seen.

Then, cut off several inches from the board using a table saw or miter. The crack won’t be an issue after this.

The PROS

Avoids warping entirely

Removes it quickly

The CONS

Loss of material

3- Patch Over the Cracked Wood

If the crack is on the smaller side, it may be just fine with an easy patch.

You could patch the wood using either superglue and sawdust or wood putty, depending on your preferences.

With the putty, you’ll want to carefully read the instructions that come on the package and follow them well; some putties have to be applied before varnish, for instance.

The sawdust and superglue method might not work with certain varnishes, as it can mean discoloration of the wood.

The PROS

A budget-friendly option
Easy to apply
Takes a shorter amount of time

Comes in many color options
Has a long life

The CONS

It might not prevent the crack from spreading as well as some other methods do

4- Fill in Cracked Wood

Filling in wood can be used in tandem with an inlay, though you can also use epoxy on its own.

Generally speaking, epoxy is self-leveling and makes for a quick fix for the crack.

After fully drying, it is a long-lasting, strong solution that can be customized with your choice of colors.

The PROS

Fills and seals in one application
Low shrinkage
Easy to color match

Excellent adhesion

The CONS

May be messy

Usually more expensive
Has a short lifespan

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Hi, I am Mark Garner a professional carpenter, woodworker, and DIY painter. I live in the small city of Peoria, Arizona as a semi-retired woodworker. I have started this blog with a simple motive to help you with my wood experience in this sector. If you like to know more about what I love doing and how it all got started, you can check more about me here.