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In this article, I show you how to fill wood voids with epoxy resin. Also, learn the best epoxy for filling wood voids, knots, and cracks.

This 2 step technique I use in this article correctly repairs and stabilizes wood voids.

So, let’s dive in with a list of tools and materials.

Tools and Materials

Deep Pour Epoxy
Epoxy Resin (Fast Curing)
Mini Torch
Card Scraper
Burn In Stick
Rotex Sander
Table Top Finish
Router
Router Slab Flattening Bit

Project Overview

First, this article is part of a the DIY walnut epoxy dining table build series.

I incorporate unique and reclaimed wood in most of my woodworking projects.

Many of these live edge wood slabs have structural issues that need to be addressed before I can use them for furniture. As a result, I use epoxy to repair large wood voids as well as a burn-in stick for smaller wood defects.

Epoxy works great for filling knots, cracks, voids and other wood defects as it repairs and stabilizes rotted wood.

My 2 step technique I use in this project shows you how to fill wood knots with epoxy correctly.

Although I used clear epoxy in this project, I often use colored epoxy, glow powder, or turquoise to fill cracks in wood.

Prepare Surface Area

I prepared the surface area before I fillled wood defects with epoxy to ensure proper adhesion.

First, I rough sanded the surface with low grit sandpaper to expose small holes, cracks, and other wood defects.

Rough sanding removes much of the dirt and debris which hide wood defects.

Rough Sanding Live Edge Walnut Slab

Next, I loosened the debris with various tools and vacuum them up from within the wood voids.

Ultimately, proper surface preparation is key to successfully fill voids in wood with epoxy.

Seal Underside of Wood

In my experience with various wood species and live edge slabs, I find most wood defects extend to the underside of the wood.

Also, all large voids in wood extend to the underside of the wood.

As a result, I sealed the underside of the table with tuck tape (any sheathing tape works) to prevent epoxy leaks.

Best Epoxy for Filling Voids in Wood

As I mentioned, I use a 2 step process to properly fill defects in wood with epoxy.

My 2 step process consists of using different types of epoxy.

I use deep pour epoxy for the first step, which is mixed at a 2:1 ratio.

For the second step, I use an epoxy with a 1:1 mixing ratio. This epoxy normally cures within 24 hours.

Deep Pour Epoxy

For the first step, I used deep pour epoxy to partially fill the wood voids.

As I outlined in my best epoxy resin for wood projects, I use chill epoxy and liquid glass as my preferred deep pour epoxy.

Deep pour epoxy penetrates and seals very well which allows it to fill all voids and soak into the wood fibers.

In addition, it cures slowly which makes for a stronger bond.

best deep pour epoxy for river desk

For the second layer, I used a table top epoxy resin with a 1:1 mixing ratio. This resin cures quickly and thicker than deep pour epoxy.

table top epoxy

Fill Wood Voids with Epoxy

First, I filled the cracks, knots, and voids with deep pour epoxy.

How to fill wood voids with epoxy
How to fill wood voids with epoxy
filling wood knots with epoxy

I allowed the epoxy soak in for a few minutes and added more until the wood void was half full with epoxy.

As a quick tip: Some wood voids require more epoxy than others so be sure to keep an eye on it after you pour.

The purpose of the first epoxy layer is to penetrate and seal the wood. In turn, I poured enough to partially fill the holes.

how to fill wood knots with epoxy

Remove Epoxy Air Bubbles

Next, I used a mini torch to heat the resin for even better penetration and to remove air bubbles.

remove epoxy air bubbles
fill knots with epoxy

Then, I allowed the deep pour epoxy to cure for 24 hours.

A 24 hour cure time allows the epoxy to partially cure and adhere to the next epoxy layer.

2nd Epoxy Layer

I used total boat table top epoxy to fill the wood voids, cracks, and knots.

filling walnut slab crack with epoxy

To avoid unnecessary sanding, I filled the wood void until it reached the wood surface. I allowed it to soak for a few minutes and poured more if needed.

Ultimately, I needed to pour an epoxy river and flatten the walnut dining table.

So, I wasn’t too concerned with the epoxy overflowing.

stabilize wood knot with epoxy

Once the epoxy dried, I poured a blue epoxy river, flattened the wood slab table with my router, and sanded the table smooth.

These steps were part of the DIY Walnut Slab Dining Table full build.

2 inch epoxy pour
epoxy deep pour second layer
flatten wood slab epoxy table
epoxy wood sanding technique
epoxy resin sanding technique

Use Burn-In Stick for Small Holes

After I flattened and planed the table, I noticed a few tiny holes near the wood knots, cracks, and voids.

So, I used a burn-in stick to fill them. I only use a burn-in stick for small wood voids.

filling holes in wood with burn in stick

First, I adjusted the flame on my mini torch to low.

filling holes in wood with burn in stick

Next, I applied heat to the burn-in stick until it became soft.

filling holes in wood with burn in stick

Then, I smeared the soft part of the burn-in stick to fill the small wood voids.

I repeated this process until there were no voids remaining on the table.

As a final step, I removed the excess with my card scraper.

When the wood shavings produced by the card scraper change colors, I know the excess is gone.

remove excess burn-in stick with card scraper
remove excess burn-in stick with card scraper
remove excess burn-in stick with card scraper
how to fill wood voids with epoxy
how to fill wood knots with epoxy
how to fill wood knots with epoxy

Sand & Apply Finish

Once I removed the excess, I sanded with 320 grit and applied rubio monocoat oil plus 2c finish.

sand epoxy wood table with 320 grit
apply rubio monocoat to epoxy wood table
apply rubio monocoat to epoxy wood table

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    I hope you learned how to fill wood voids with epoxy and use it on your next DIY project.

    diy walnut slab epoxy dining table

    Frequently Asked Questions

    What do you use to fill wood cracks?

    Epoxy works great to fill wood cracks and repair other wood defects. Additionally, a burn-in stick works to fill small wood voids and cracks.How to Fill Wood Voids with Epoxyfilling wood cracks with burn in stick

    How do you fill wood with colored epoxy?

    To fill wood with colored epoxy, mix epoxy, add pigment powder or resin dye, and stir well.add pigment powder to epoxymix pigment powder with epoxy

    What is the best epoxy resin for wood?

    Total Boat table top epoxy is the best all around epoxy for wood. It works well on a table top, epoxy inlays, and for fixing wood cracks and voids.Total Boat Epoxy Table Top

    How do you prepare wood for epoxy?

    To prepare wood for epoxy, remove loose debris and sand the wood.Rough Sanding Live Edge Walnut Slab