Will An Epoxy Top Coat Stop Wood From Splitting?

Have you started to see small cracks and splits appear on the surface of wood? Wood cracks (also known as wood checking) is a surprisingly common problem when it comes to working with ‘green’ wood.

Now, green wood is the name given to freshly logged lumber. When wood is first cut, it has a lot of moisture in it. But, after seasoning (which can take months) much of the moisture in wood will have evaporated away.

However, if you don’t give wood time to season and start using it fresh, it will continue to dry out. Except now you will have to deal with wood shrinkage — which can lead to cracks appearing all over your wood craft.

But can an epoxy coat help to prevent wood from splitting apart like this?

Well, in this post, you’ll learn why wood starts to crack — and why seasoning is critical to preventing wood from fracturing. You will also find out the two most practical ways to stop wood from splitting.

And keep reading to discover out whether or not epoxy can actually help prevent wood from checking.

will epoxy stop wood from splitting

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Why Does Wood Split And Crack Apart When It Dries?

It’s all because of wood’s moisture content.

Freshly cut wood has a lot of water saturating its wood fibers. This is known as woods ‘moisture content’. And freshly logged lumber has a moisture content of nearly 100%.

But all of that excess water can make wood unstable. Especially when wood’s moisture content begins to evaporate.

So, before we start working with any piece of wood, we need to let it air-dry. And this air-drying process is what we refer to as wood ‘seasoning’.

Yet, as wood dries out, it will begin to contract and shrink down. And this is still the case regardless of whether or not you start working with wood — before it’s seasoned — or not.

What’s more, the faster wood dries, the faster it’ll contract. And if it contracts unevenly, it will begin to do something called ‘checking’.


And once wood starts to check, (i.e. crack), it’ll become far too brittle to make anything with.

Got It…So How Do You Keep Wooden Furniture From Checking?

The only way to fend off wood cracks is to try and slowdown that evaporation. This is because the faster moisture escapes, the worse things are going to be for that timber.

So, there are generally two ways you can go about doing this;

1). Regulate The Humidity In The Area

This option involves managing the moisture in the air around a furniture item or wood craft. As long as you maintain humidity levels at a range of 45% to 65%, you’ll prevent wood from drying out too fast.

But regulating the humidity in a space isn’t always the easiest thing to do. So this is why your next best option is to simply…

2). …Apply A Waterproof Sealant

This alternative approach involves sealing the surface of wood using a waterproofing sealant. The sealant will prevent moisture vapor evaporating away.

Applying a sealant, (especially over the end grain), will prevent wood from drying too fast.

IMAGE OF Face v End v Edge Grain

But the key to this approach is making sure you use a waterproof sealant, such as a polyurethane or urethane sealer. Especially if you happen to live in a very warm climate.

And why is that? Well, because most widely used wood finishes, tend to be microporous. Which means they aren’t going to be waterproof enough to prevent wood cracking during very hot months.

Wait A Second…What Exactly Do You Mean By A Microporous Finish?

Well, a microporous wood finish, (such as Tung oil or Linseed oil), are water-repellent, but not waterproof. This is because, while these finishes can prevent water droplets from sinking past, they aren’t able to block vapor.

So, they won’t prevent wood from becoming damp in very humid environments. And they won’t stop wood from drying out in very hot dry climates either.

This lack of waterproofing is one of the main reasons why microporous finishes become damaged if you place a coffee cup on them. That combination of high heat plus condensation will sink right past a microporous finish and ruin the wood underneath.

What About Epoxy? Is It A Waterproof Finish?

Well, first off, epoxy is not a microporous finish. So, you don’t need to worry about that.

In fact, once epoxy has hardened, it is probably one of the most waterproof wood sealing finishes you can use — besides polyurethane/urethane.

Related Post: Can You Apply Epoxy Over Polyurethane? (Your Questions Answered!)

OK. But Will Epoxy Be Waterproof Enough To Prevent Wood From Splitting?

If you were to seal wood with epoxy, then a coat of this hard finish will reduce the rate of evaporation.

However, the way people tend to use epoxy to fix wood cracks, won’t work.

You see, if you plan on packing epoxy into an already-present crack, then that doesn’t solve the real problem — which is fast-evaporation.

The epoxy itself will be stable — but the fast-drying wood won’t be — and that timber will continue to contract. And eventually, wood will simply continue to crack and split around the epoxy filler regardless.

Related Post: Can You Apply Epoxy Over A Tung Oil Finish?

To Wrap Up, Here Are The 3 Key Takeaways From This Post…

  • 1). When wood starts to split, it’s because of moisture evaporation. If the moisture in wood dries out too quickly, wood will contract and split.
  • 2). The simplest way to prevent wood splitting is to prevent wood from drying out too quickly. The most practical way to do this is to seal exposed wood grain with a penetrating oil or waterproof sealer.
  • 3). Epoxy is a waterproof sealer. If you seal wooden surfaces with this finish, it can prevent wood from drying out and cracking. But, if you use epoxy to fill in cracks, it won’t be able to stabilize that crack if wood continues to shrink.