Epoxy is basically like having a superpower in your back pocket, and using it when the chips are down.
It’s wonderfully malleable; you can use it like cookie dough or clay, making it exactly what you need it to be and applying it where it’s needed.
It’s one of those things that you just need in your woodworking shop.
Whether it becomes part of your normal routine or you’re just using it for repairs, it’s a lifesaver. You’ll be glad you stashed some away for the occasion.
But it’s not all powerful.
There are limitations, and you should only use it a certain amount of the time. Let’s define the boundaries, discuss the benefits of it, and teach you how to repair seemingly destroyed wood from start to finish.
What Exactly is Epoxy?
Epoxy is an adhesive, first and foremost.
On its own, epoxy is actually organic until it’s mixed with chemical elements.
On a basic level, it’s a chain of carbon, hydrogen, oxygen and nitrogen in a never ending pattern, one that creates an insane bond.
You have to pay attention though, because epoxy is a term that can be stretched. It could mean an epoxide functional group, which is basically a manipulative of epoxy. It’s not quite the same thing.
The organic compounds in epoxy are met with a chemical agent or activator, If you don’t use one of these, then it’s not going to do what you want it to do.
The organic compounds would just be like a watery substance, but chemical additives change the game. They are what allow the epoxy to harden and become useful.
The reaction is quick, and it’s something you don’t want on your hands. It becomes a hard polymer, one that is resistant to a vast number of things.
There’s different types of epoxy for different materials, because it has to mimic the same strength of that material. It would be amazing if it just conformed to its application and followed suit, but it’s actually through chemical engineering by manufacturers that this can happen.
Different grade of epoxies get different chemical catalysts added to them.
Some of them make the epoxy more resistant to moisture, some make it more heat resistant, and so on and so forth. You can get a general epoxy that will do a basic mix of all these things.
Epoxy needs to be cured, which can occur both prior to and post manufacturing.
Every type of epoxy will have varying dry times, and if those aren’t met with diligence and attention, the epoxy won’t reach its full strength. Some epoxies take ten minutes to fully harden, while others can take twenty-four hours for the full chemical reaction to hit.
Can Epoxy be Used on Wood?
Yes, it most certainly can be used on wood.
It actually sticks to exposed wood fibers like a dream come true, making it an ideal agent for multiple woodworking projects.
Wood is extremely fibrous, and that’s where the magic lies. We sand wood to prepare it for something else, for something to stick to it.
That’s because the fibers can’t pop through a varnish or shellac that’s on top; it needs to be exposed before anything new will stick to it.
If you were to paint exposed wood, it would stick right away, but if you put a coat down on a slick table that’s been treated with polyurethane, it’s not going to do anything.
Sanding releases those fibers. If you’re using epoxy to fix large scratches or divots in your hardwood flooring, you will have to sand it down and remove the finish.
It’s unfortunate, but when you refinish the floor, it’s going to stick out a bit. Most of the time, people will let little gashes go until they can devote time to sand, epoxy, and refinish the entire floor in one room.
Is Epoxy Stronger Than Wood Glue?
Every adhesive material is going to have its limits, but epoxy has farther limits than wood glue.
Even if you go with a trusted glue brand like Gorilla (and they make great wood glue, we’re not putting them down), epoxy is still going to be stronger for a number of reasons.
The most important is that it penetrates the fibers of the wood in a way that glue does not.
Glue binds two pieces together by basically holding onto the wood, but epoxy will sink into it and basically make the wood its home.
It makes it a lot more difficult to remove, since epoxy is meant to be used forever.
Epoxy is stronger than wood glue when it comes to heat resistance.
Glue will melt over a certain temperature, but epoxy is heat resistant and ready to withstand a beating. Since epoxy is often cured at temperatures of 250-350°, you’d really have to be trying to melt it off of your projects.
How do You Color Epoxy?
There are two main methods.
Coloring epoxy will drastically change how it looks with a very little amount of dye. It’s as if the polymer compounds welcome the coloration into its chain, and adapt to it entirely.
The first method is to use a chemical dye. You can find resin epoxy dyes everywhere, and most of them are UV treated.
Colored polymers (like plastic) are only susceptible to damage from ultraviolet rays, so getting UV-resistant epoxy paint is not only going to retain the color, but it’s going to protect the wooden project that much more. No sun damage means a longer lifespan without losing luster.
If you don’t want to use a chemical dye, that’s okay. This step gets a little tricky, but once you do it the first time, it’ll be a cake walk.
You need to get something called pigment powder. It doesn’t matter what brand, but pigment powder is what’s going to do this. It doesn’t matter if it’s a one-stage epoxy or a two-stage.
Gently apply about a quarter of an ounce to your epoxy (usually 8 oz jars or containers), and stir it with a simple wooden paint stirrer.
The reason why many woodworkers don’t like using powdered pigments is because it tends to fleck and get into the epoxy. Then you spend a few minutes scanning the epoxy and removing anything that sort of clumped up.
Adding a color to epoxy could increase the drying time. If you’re using a fast-drying epoxy that takes about ten minutes, assume twenty. If it take an hour, assume two.
Most epoxy dries clear, but with coloration you don’t want to touch the surface to find out that you messed up how clean and cohesive the color bonded to it.
One last word of advice: some epoxy will have a yellowish tinge to it.
Pay attention to the labeling to find out if it dries on clear. Something happens during application that will make the coating translucent, but it could affect how the colors blend into the epoxy.
How do You Prepare Wood for Epoxy?
Make a mishap during this step, and it could cost you the aesthetic appeal of your entire project. Epoxy is powerful, and it’s tough as nails to remove once you apply it.
Be very meticulous while preparing your surface, and do it indoors so that wind and dust aren’t an issue.
First of all, clean the surface off before you do anything.
Finger grease, oil, wax from wood storage—there could be a ton of things silently lurking on your wood.
You need to clean it off effectively before continuing, otherwise you’ll end up sanding the contaminants into the wood. That’s going to make applying epoxy a lot more difficult.
Next, dry the surface off. Whatever you used to clean it needs to be wiped off the surface. If you think that all the moisture has been removed off the wood, you’re likely wrong.
Wood fibers suck in a lot of moisture. Give the surface about twelve hours to dry before continuing.
Then it comes down to sanding. Do not use anything over an 80 grit sandpaper. The higher grit the sandpaper, the finer and smoother the surface is going to be.
That’s not what we want: we need it to be a bit coarse so that the epoxy has something to cling to. You can use a low grit belt sander here to get the job done quickly, and touch up any unique areas with a sanding block.
When you’re completely done, take a vacuum cleaner and a narrow nozzle attachment.
Use suction around the edges of the project first and gradually work inward.
Even after you think all of the dust is gone, give it a quick wipe with a dry paper towel at the end to be completely sure. We want to apply the epoxy to a totally clear and clean surface.
What Tools do I Need to Use Epoxy?
Since there is a chemical agent at work in the epoxy, it’s dangerous to get on your hands.
You’re going to start by getting some thick latex gloves and slipping them on.
Apart from that, you just need a cheap and thin paintbrush that you don’t mind ruining.
Apart from that, a heat gun will help speed things up a bit, and you will need some rags handy to keep everything clean and clear.
Step by Step Guide
Heres a short step by step guide on how to do it
1. Inspect the wood
How extensive is the damage?
You’ll have to gently poke and prod the affected or rotted area before you continue.
Use a wood chisel to lightly remove bits of the damaged wood, but don’t take away more than is necessary.
Use a shop vac attachment and a brush to remove all the remaining debris; we don’t want that sticking around when it comes time to application.
2. Clear our the area
Once the area is completely cleared out, get your paintbrush and your can of epoxy.
Gently dip the end of the bristles into the can, and make sure you don’t saturate the brush.
We don’t want any runoff to spill on other parts of the wood.
3. Slow passes first
Bring it over the specific area, and make short, slow passes with the brush.
Give the epoxy a little bit of a chance to seep into the wood and get captured by the fibers. Wait about ten to fifteen seconds, and do another small pass.
Eventually, the epoxy will begin to build up. Once you’ve reached the desired amount in the crack, break, or rotted part of the wood, you’re done with the brush.
Use a heat gun to treat certain areas of the epoxy resin as it dries.
If the epoxy starts bubbling, that’s bad: pull back.
Epoxy is cured at a max of 300°, and while your heat gun isn’t likely to reach that high and change the epoxy temperature, humidity can also attribute to epoxy failure.
Give the epoxy enough time to dry.
If you colored it to match the wood stain or type, give it twice as much time to dry as you normally would.
Once it’s dry, you can sand it down just like you would with wood, and check the finish when you’re done.
It should feel sturdy, and provided you got the right epoxy type for the task, it will have a similar feeling when you brush your hand over it. You’re done.
Is Epoxy Toxic?
Any time you use a chemical, you should have a respirator mask.
Epoxy isn’t as toxic as most people think. After all, it began as an organic compound, and the chemical additives are technically what makes it dangerous.
Most of the risk with epoxy comes from toxicity through ingestion, and I think it’s safe to say that you’re not planning on taking a sip out of the epoxy can anytime soon.
We put on gloves for that project earlier because it can be damaging if it gets on your skin. Your pores could absorb it, and it would be toxic at that point.
If you’re using gloves, you’re good. If you’re not ingesting it, you’re good. Your respirator mask will have to be in full working order, otherwise you’re running the risk of getting dizzy and nauseous from the fumes.
Epoxy chemical catalysts are labeled on the side of the can, but since we’re not all walking MSDS containers, look at the warnings and toxicity portion of the label.
You will see the same bits that we see on everything about washing your eyes out, and being 100% certain that it’s not going to get on your skin.
If you have the time and find the right epoxy for you, inspect the additives to understand the risks before using it.
Is One-Stage or Two-Stage Epoxy Better?
Some of it comes down to personal preference, and very little of it revolves around the strength of the epoxy.
If you’re not certain which works for you, it’s best to try both of them out and determine what works best after experience and application.
What is One-Stage Epoxy?
A one-stage or one part epoxy is generally used in smaller applications, such as aerospace-grade use, mechanical and engineering, and is generally not the choice of woodworkers.
One-stage epoxy can’t sustain itself in temperatures above 75°, otherwise it starts to degrade. It won’t melt like it would during the curing stage, but instead will just fail altogether.
Whatever it is attached to will simply fall apart.
One-stage epoxy is used in electrical and mechanical engineering as an adhesive in place of glue.
Because it can combine with multiple different types of metals and polymers, you’ll see it used with wires and small electronics.
It’s more versatile, but it’s a little more catatonic with that low temperature threshold.
What is Two-Stage Epoxy?
Remember that chemical additive we were talking about earlier?
Two-stage epoxy doesn’t have that chemical added to it yet; it imbues with the catalyst directly before application.
You might have to mix equal parts chemicals into equal parts organic epoxy in order for it to work, or you might find pre-packaged epoxy containers that blend them together as you use it.
Two-stage epoxy is the one that sustains high temperatures, but it also costs a fair deal more.
Woodworkers prefer this because it can bind metal and wood together, and stand the test of time during a repair where it’s sanded, treated, and painted.
If you are going to mix two-part epoxy components together in your own woodworking garage, make sure you’re wearing the appropriate clothing for the job.
Just Like New
Epoxy is insanely powerful in the way that it not only repairs the structural integrity of wood, but how flawless it looks when everything has dried.
You can sand it, refinish it, and nobody will be the wiser.
As one of the most essential repair items in your woodworking arsenal, it’s important to seal your cans properly to keep your supply in perfect order.
If you’re just getting into woodworking for the first time, buckle up: epoxy is about to be your best friend.