Epoxy resin is used for a lot of different things and can be used together with lots of different materials. But will epoxy resin adhere to wood?
Epoxy resin will adhere to every type of wood. The strength of the adhesion depends on the viscosity of the resin and on the surface energy of the wood. Epoxy will also adhere to varnished wood, stained wood, and oiled wood without any issues and without any sanding required.
Epoxy resins adhere because of attractive polar forces in the resin and the surface it has contact with while curing. When the surface energy of a material is higher than that of the epoxy resin then it will create a strong bond.
Surface energy is a measurement of how many potential unfinished atoms there are that want to react with something. You can read more about surface energy right here or if you want a more simple explanation then consider reading my guide on what epoxy resins are and how they adhere.
Every type of wood as well as every type of varnish, oil, and wood stain have a higher surface energy than epoxy resin. So Epoxy will create a strong bond with all of them.
The adhesive strength of epoxy resin has only very little to do with how porous the wood is.
The viscosity of the resin has something to do with the adhesive strength though. The more liquid the resin is the more contact it will have with the surface of the wood thus creating a stronger bond.
Choose the Right Kind of Resin
There are a lot of different kinds of resins and choosing the right type for your project will help a lot with the results.
Generally, for working with wood you want a liquid type of epoxy resin. I highly recommend either “deep pour epoxy resin” if you want to pour the resin in a layer that is thicker than 5 cm or “art resin” if you want to apply a thin layer of resin to your wooden project.
Kneadable epoxy resin, two-part epoxy glue, and UV-resin will also work on wood.
Kneadable epoxy resin needs to be pressed firmly to the surface of the wood to ensure a strong adhesive bond, though.
That is also why I don´t really recommend using kneadable epoxy for woodworking projects. There are other things like wood filler or wood glue that can be used instead and will yield better results.
Two-part epoxy glue works just fine but I only recommend using it for gluing wood to other materials. For gluing wood to wood regular wood glue is still better, cheaper, and easier to use.
UV-resin can be used on wood and you can achieve great results with it but I only recommend using it for smaller applications as it is more expensive than regular resin and tends to warp if you don´t cure it evenly enough.
The Type of Wood is Important
Every type of epoxy resin will adhere to every type of wood but the strength of the adhesion is still somewhat dependent on the type of wood.
Different type of wood has different surface energy and the higher the surface energy the stronger the adhesive bond with the epoxy resin is.
There is a neat trick to see how high or low the surface energy of wood is. Simply drop a single drop of water on the untreated surface of the wood.
If the water drop is absorbed right away then the surface energy of the wood is high and the resin will adhere very well to it.
If the water drop is absorbed very slowly then the surface energy of the wood is not that high and the resin will adhere less well to it.
The surface energy of surface free energy of wood can be slightly increased by rough sanding the surface of the wood with some sandpaper.
The Finish of the Wood Can Impact the Adhesion Strength
If you are working with wood that has already been sealed, oiled, or stained then the adhesive bond with epoxy resin will be different.
It generally doesn´t matter how the wood was sealed as the epoxy resin will adhere to stained wood as well as varnished wood.
Even wood that has been sealed with epoxy resin is no issue as epoxy resin adheres very well to itself.
But even though the epoxy resin will stick to every type of surface finish that is commonly given to wooden surfaces it will adhere better to some surfaces than to other.
It generally doesn´t matter that much but just for interest’s sake. Epoxy resin will generally stick better to varnished wood and stained wood than to wood that has been sealed with epoxy resin.
Epoxy resin will not adhere well to oiled wood surfaces.
How to Apply Resin to Wood
This is only a quick little guide on how to apply resin to wood.
- Apply some varnish or resin to the surface of the wood
- Seal any holes and gaps with acrylic sheets or tape
- Mix and color the resin
- Pour the resin
- Pop bubbles by torching the resin
- Remove the acrylic sheets and tape after the resin has cured
- Sand and polish everything
These are the basic steps of applying resin to wood.
Before you apply resin to a wooden surface you have to make sure that the resin doesn´t bleed into the fibers of the wood or you will end up with discolored areas where the resin touches the wood.
To avoid this discoloration simply apply very small amounts of resin to the surface of the wood that will later touch the resin. You are basically coating the surface with resin.
This resin coating will act as a barrier for the resin later on.
Let the coating cure and then seal any holes or gaps with either acrylic sheets or tape.
This will keep the resin where it is supposed to cure.
The rest of the process is pretty straightforward. Simply mix the resin accordingly and color it if you want to. I have a full guide on coloring resin properly right here if you want to know more.
And then pour the resin. Make sure to cover everything properly and use a toothpick to push the resin all the way to the edge of the wood if you need to.
Use a blow torch to get rid of any bubbles that are forming inside the resin while it cures.
Once the epoxy resin has cured, simply remove the tape and the acrylic sheets and sand everything down. Resin needs to be wet sanded with very fine-grit sandpaper to get it back to a transparent finish.