Woodworking is both an art and a science, with creations that are not only functional but also visually appealing. However, as with any craft, there’s wear and tear. Over time, even the finest wooden items can develop small cracks or gaps and it’s essential to preserve their beauty and integrity.
So in this guide, I’ll share how you can fill cracks in wood with epoxy, along with the detailed steps and tips!
What Type of Epoxy Fills Cracks in Wood?
There are two types of epoxy filler that are commonly utilized for filling voids in wood: liquid epoxy and wood epoxy putty. These options provide effective solutions for addressing gaps and imperfections in wooden surfaces.
Epoxy Wood Fillers vs Liquid Epoxy
Liquid Epoxies
Liquid epoxies are recommended for large cracks and holes found in wood. It has a low-viscosity epoxy property which makes it a good choice for filling in large wood voids. The liquid can easily reach the bottom of the hole and soak the fibers in the process.
Epoxy Wood Fillers (Putty Version)
Epoxy wood filler (wood putty version) is the top choice when dealing with small cracks and voids. It is not recommended for larger voids and larger cracks. This product results in a bond that’s very durable and has a quick curing time. Check the top-quality epoxy wood fillers here!
Filling Cracks & Voids in Wood Using Epoxy: The Step-by-Step Process
Learning how to fill cracks in wood with epoxy resin is not complicated. It is generally an easy process. In addition, once it is completely dry, it creates a strong protective covering. You can also tint the resulting epoxy products so that it matches the exact color of the wood.
Tools/Materials You’ll Need
- Pigment
- Two-part liquid epoxy
- Sandpaper
- Needle
- Latex gloves
- Sheathing tape or tuck tape
- Sanding block or orbital sander
- Disposable container
- Disposable spoons or stir sticks
Step #1: Pick the Best Epoxy
Before you dive in, it’s essential to invest in the best epoxy resin you can find. Your choice should be driven by both the quality and strength suitable for your woodworking project.
Before using it on your kitchen or dining area, find out if epoxy resin is food-safe first.
Always remember that you get what you pay for. So make sure to buy the best epoxy product and steer clear of cheap brands. These products may have low-quality formulations that will not help you achieve a smooth result.
Purchase epoxy from a brand that you trust and have tested.
Recommended Read: Epoxy vs Resin
My Recommended Epoxy for Filling Cracks & Voids in Wood
Over the years, I’ve tried and experimented with various epoxy formulations to find the best match for my woodworking needs. After numerous trial and errors, I came to particularly appreciate the TotalBoat Penetrating Epoxy for filling wood cracks and voids.
One of its standout features is the straightforward mixing process, which is user-friendly in terms of ratio. The dispenser it comes with is quite efficient, giving out enough product.
It will prevent you from using too much epoxy. It also targets small cracks and fill voids well in a few minutes.
But for more options, you might want to check this review of the best epoxy resins for thick pours!
Step #2: Set the Open Time You’ll Need
Another thing to consider is the amount of time needed to work with the product. This time refers to the duration you work with the product while it is in its liquid state, also known as open time.
The majority of epoxy has an open time of approximately 5 to 60 minutes. If this open time is reached, the epoxy liquid turns into a gel that hardly flows.
You will need more time to fill cracks in wood or holes that are larger compared to the smaller ones. Make sure to purchase a product that can give you enough preparation time and successfully fill wood cracks without a hurry. Do not skip this prep work.
Step #3: Prepare the Wood Surface
Prepare the wood surface layers by cleaning them. Make sure to include the knots, cracks, and voids when cleaning the surface. If the wood has small holes or a larger one, loosen the wood fibers by using a sharp tool that is available for you.
Sand the surface, then clean off the sawdust. Examine the wood if the holes go through on the other side. If this happens, make sure to seal it with the use of masking tape.
Sealing the Underside of the Wood
- Clean the underside of the wood
- Sealing the underside is easy using tape. Make sure to seal the corners as well.
Step #4: Start Mixing Two-Part Epoxy Fillers
Start mixing the two-part epoxy fillers with a 1:1 ratio. Mix together equal parts resin and the hardener.
Check the manufacturer’s guidelines as well to see if this ratio is okay. Place the hardener into a container, then the resin, and mix thoroughly.
Continue to scrape on the sides as well as the bottom of the container. Continue to mix until the mixture becomes transparent and crystal clear. Make sure to use the recommended amount of the hardener.
Tips for Mixing Epoxy Fillers
1. Before you start to mix epoxy, determine the correct mixing ratio of your epoxy. Resin can have different ratios, and it is best to know which ratio is correct for your epoxy.
2. Mix the epoxy based on its volume instead of its weight.
3. Keep in mind and check the ambient temperature of the environment. Epoxy is sensitive to heat, and it will do you good to determine the current temperature when handling this product.
4. Check the humidity levels when you attempt to mix epoxy. Epoxy is also sensitive to humidity.
5. Be careful when mixing the product. Also, make sure to use the appropriate tools to mix it.
6. Purchase and apply premium quality epoxy fillers or epoxy sets.
Step #5: You Van Tint the Epoxy (If Needed)
You can also tint the epoxy to match the exact color of the wood. This step is optional and easy to do. The usual coloring products used include mica powder.
Drop a small amount of tint into the epoxy and mix it using a spoon. Continue to mix until the preferred tone has been achieved. Make sure to add the tint bit by bit.
You can tint epoxy products so that they will match the wood to create an illusion that there are no traces of epoxy.
Step #6: Now, Fill the Cracks in the Wood
Once you are done with the wood surface preparation, you can now start to fill a wood crack found on the wood. Do not worry since this step is easy.
Make sure to carefully deep-pour epoxy in the wood voids and fill cracks in the wood. Slightly overfill the wood voids or wood cracks.
The majority of the epoxy formulation will cure and dry for approximately 24 hours. Allow the mixture to dry longer if you find it necessary.
Suggested Readings:
Step #7: Get Rid of the Epoxy Air Bubbles
Next, examine the epoxy closely. Check for air bubbles, and if there are any, make sure to remove these before the product sets. One thing you can do is to poke the air bubbles by using a needle or your putty knife.
You may also heat the surface using a handy propane torch. The heat will warm the resin, which will make the bubbles float and eventually disappear.
Step #8: Strip the Tape and Start Sanding the Cured Epoxy
Remove tape and initiate the sanding process once the spot has been filled, fully cured, and dried down. Sand the overfilled gap and make sure that it matches the surrounding wood. Wrap the sandpaper onto a block and proceed to sand along the grain.
Make sure to keep examining the sandpaper or sanding block if it is filled with epoxy. This will make the sandpaper inefficient. If this happens, use new sandpaper immediately. (You may want to check out the best sandpapers for wood in this review!)
After addressing those significant voids or gaps in your wood, you might feel daunted by the prospect of sanding. Don’t worry! An orbital sander can make this task much more manageable. Just remember to keep it constantly moving across the surface; this ensures an even finish and helps avoid creating divots.
Step #9: Add Epoxy Layers (Optional)
This is an optional step that involves adding more epoxy layers to your project. I recommend doing this if you find gaps that are underfilled.
Overfill the gaps so that it can be easy to sand off the excess. If you have underfilled the gaps, you may need to refill it again once the initial pour has completely dried.
Step #10: Flatten and Sand the Wood Surface
Once the spot is flush with its immediate surrounding, you should stop sanding. You can now proceed to sand the entire wood to produce a smooth surface and prepare it for the final coat. The last step involves cleaning the wood shavings with a dry cloth.
Step #11: Finish the Wood Surface
Many brands will indicate whether the product is a stainable wood filler to help users choose the best product for the job. A two-part epoxy resin [1], on the other hand, is best finished with film to add shine to it.
You can use any of the following to finish the surface: tung oil, lacquer, polyurethane over epoxy, varnish, or shellac. Once you have decided on a finish, you can proceed to apply it with a roller or hand sprayer over the wood surface.
Applying Wood Finish
1. Examine the surface for any dirt and dust and proceed to clean it off
2. Using a brush apply the wood finish
3. Allow the clear casting of the finish to dry completely
4. You can check if the film finishes if it is dry by touching it
How to Fill Wood Voids Using Colored Epoxy
1. Inspect the voids and as well as several wood cracks on the surface. Then proceed to seal the side using painter’s tape or tuck tape
2. Get your colored epoxy and mix or add some tint to your liking
3. Deep pour epoxy to fill wood cracks
4. Proceed to remove the tape and then sand down and smoothen the area
5. Apply a finish of your choice
How Can You Use Burn-In Stick for Filling Small Holes?
1. Adjust the flame of the handy torch to low.
2. Apply the low heat to the burn-in stick until the product becomes soft
3. Apply the soft part of the burn-in stick when filling wood voids.
4. You can proceed with these steps when necessary
5. The final step involves removing the excess product with a scraper. This should result in a smooth and level finish that can cover knot holes.
Other Filling Options for Wood Voids and Cracks
There are other filling options for wood voids and cracks if you cannot find any epoxy. I suggest using wood putty or wood paste fillers. Another option to use instead of epoxy is wood filler sticks.
You can also make DIY epoxy filler by using sawdust mixed with an adhesive such as wood glue. You can start by mixing the sawdust with glue until you get a soft paste.
Safety Precautions to Consider When Filling Cracks with Epoxy
- Make sure to wear a mask as well as latex gloves while handling epoxy wood fillers. This will protect you from any accidents, such as spills.
- Make a mixture of the filler amount that you only need for your woodworking projects.
- Once the epoxy spills, clean it off using denatured alcohol; unfortunately, it gets to your skin using mild soap and water to remove it.
- Store the excess product in a cool and dry place away from the reach of other people.
More Epoxy Guides For You:
Conclusion
It is best to perform the necessary precautions and maintenance on your wooden pieces at home to extend their life and protect them from damage.
Learning how to fill cracks in wood with epoxy is a good skill to help maintain these pieces. I hope that this article has helped you better equip yourself on how to handle this task!
Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
