Does Epoxy Strengthen Wood?

If you’re looking to tackle a home improvement project in wood, then you may be wondering; how can you use epoxy to strengthen the wood you will use? The good news is that we’ve done all the research to ensure that you can tackle wood strengthening projects with ease.

Does epoxy strengthen wood? In general, yes epoxy will help strengthen wood. This depends on the wood, but an epoxy resin putty can be a great replacement for rotted wood and an epoxy sealer can be used to harden up rotted wood when epoxy putty won’t cut it. 

Let’s take a look at what epoxy is and how it can help strengthen wood. Finally, we’ll show you how to use epoxy to strengthen rotted wood in a practical and easy fashion for home use. 

What Is Epoxy Resin?

Epoxy resin is a catch-all term for a group of plastic compounds that, after curing, will become prepolymers and polymers (both types of complex molecules) with epoxide groups (which is where the term “epoxy” comes from) on them.

Fortunately, you don’t need to be a qualified chemist to get to grips with using epoxy resins and it has many applications including as a general-purpose adhesive, a bonding agent for cement, creating rigid foam, it can act as a non-skid coating, assist in creating stable sandy surfaces when drilling for oil, be used as an industrial coating, and, of course, it can be used in woodwork.

The finished product when using epoxy resin is generally a tough plastic that won’t shrink is impact resistant, that is resistant both to damp and chemical damage, with a long shelf-life and which contains no volatile organic compounds. 

Does Epoxy Strengthen Wood?

Epoxy resin requires two components when used in woodworking. You need the epoxy and the bonding agent which it reacts with to form the final product. You can find several different forms of epoxy that can be used in various ways.

In general terms, epoxy, when used correctly, can add strength to wood because it’s a tough, hard-wearing end product. However, it’s worth noting that much of this strength will come from the context of how the epoxy is used. 

Think about plywood, for example, a thin board of plywood is relatively easy to bend and snap by hand. Adding epoxy will make the plywood stronger but not so much that the plywood is now able to withstand huge forces. A little more pressure and the plywood will still break in your hands. 

Can You Replace Rotted Wood With Epoxy Putty?

One easy way to strengthen wood is to replace any areas of rotted wood with epoxy putty. This is a very easy repair to conduct by yourself. The simplest way to do it is to buy some epoxy wood repair putty.

Remove the rotted wood with a knife or other tool and then soak the remaining wood fibers with liquid epoxy. This will harden up the fibers that are there and make it easier for the putty to bond.

Then mix your two parts of the epoxy wood repair putty which will provide you with a nice soft, putty that you can easily shape to the hole that you want to fill. 

If you want to speed up the reaction at any point, you can use a hairdryer to move things along. You can warm the two halves of the mix to create the putty faster, you can warm the surface you apply the putty to and you can even warm the putty once it’s in place to give the curing process a boost.

Can You Strengthen Rotted Wood With Epoxy?

Sometimes, you don’t have the luxury of being able to clear out the rotted wood and start again with epoxy putty. Well, the good news is that you can use an epoxy resin hardener that will strengthen rotted wood for everyday use. 

Rotting wood is caused by the action of fungus and bacteria within the fibers of the wood. Not only will an epoxy resin help to toughen up the overall structure of the wood but as long as it is applied correctly – it cuts air and water off from the fungi and bacteria present, which stops the rot from spreading any farther.

In the long-term preventing the rot from spreading will ensure that the wood cannot get any weaker, which is important for peace of mind when working with rotten wood. 

Don’t Use A Cheap One-Part Wood Hardener

One-part wood hardeners are a bit cheaper than epoxy resin but only marginally so. However, they work using a completely different mechanism – they’re made of acrylics that are dissolved in a solvent.

Unfortunately, this makes them vulnerable to any exposure to water and they don’t bond particularly securely to the wood fibers, either. 

Over time, they become rigid and as the wood moves around with heat, light, moisture, etc. the bond will begin to wear. Any filler layers you decide to use over a one-part wood hardener are likely to suffer too. 

How To Strengthen Rotted Wood

The good news is that strengthening rotted wood with an epoxy sealer is not a difficult process and anyone can master it. You prepare the wood, mix the sealing agent, apply it and then allow it to harden. 

How To Prepare Rotted Wood

You have to get the wood ready to work on before you can add the epoxy sealer. Begin by pulling out any parts of the wood that are easily ripped off by hand, that wood is so damaged that it cannot be repaired and it’s better to replace it with epoxy than it is to try and firm it up.

Anything that doesn’t crumble to the touch can probably be saved after you add the epoxy it ought to become much harder. In fact, you should have no problem attaching fixings and you might even be able to ensure that a fully rotten beam can handle joists again!

How To Apply The Epoxy Resin Sealing Agent

Most epoxy sealing agents for rotten wood is very easy to mix. They normally have a 1:1 mixing ratio so you can mix it easily, make sure to choose the right container to mix the epoxy and you should be able to get the mix right without thinking about it.

When you get around to working with an epoxy sealing agent, we’d recommend working with a disposable brush though if you want to be able to reuse the brush because you don’t have a disposable one to hand – you can use a lacquer thinner to clean it afterward.

You Want Lots Of Sealing Agent

You want to add as much epoxy to the wood as you can, the sealing agent should soak into the rotted wood and as the solvents evaporate it will start to harden. 

On very large pieces of wood, you can short cut this process by drilling into the wood and pouring the sealing agent into the holes via a funnel. The agent will then move along the grain into the timber.

How Many Coats?

You will, almost certainly, need multiple coats of sealing agents and you need to wait for the first set of solvent to evaporate before you can add another application. The timber must be kept dry while you wait for the solvent to evaporate. 

Once the wood has taken as much sealing agent as it can handle, you should let the solvents evaporate and then add a top coat of epoxy resin which will bond to the epoxy sealing agent. 

How Much Harder Will The Rotten Wood Be?

Assuming that you’ve added enough coats of sealing agent – the rotten wood ought to have a very durable surface and, in most cases, you’ll be able to add fixings to the wood without a problem.

You should test the wood to the touch before you begin working with it. 

What To Do After Using The Epoxy?

Once you’ve completed the epoxy restoration of your rotted wood, you can now paint or varnish it. If your wood is exposed to direct sunlight you must add a top coat because there is no UV tolerance for the epoxy sealing agent (and thus, it will weaken in direct sunlight). 


Does epoxy strengthen wood? Epoxy can’t work miracles but yes, it will help to strengthen wood. In the case of rotting wood – it can be used to replace small sections of rotted wood and it can be used to harden up larger sections. All you need to do is follow our simple process and you can be working with epoxy to deliver great DIY improvements in no time at all. 

Damien Madeira

Damien has been doing woodworking for the last 5 years. He began as a hobbyist with hand tools and slowly worked his way up to own larger machines and mill rough wood into beautiful creations. While still considering himself a hobbyist, he has a passion for woodworking and enjoys working with epoxy as well.

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