Filling Knots with Epoxy

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Some of the most amazing pieces of wood are the ones that have “defects.” Defects could be spalting (mold), small checks, bark inclusions or, in this case, a huge hole. Sure, we could cut around those things and eliminate them, but I’m a huge fan of including this character in the final piece. I think it helps make my projects unique, and capitalizes on the natural beauty of wood. So, let’s look at filling knots with epoxy.

The Resin

The product that will give us the best results for filling knots with epoxy is casting resin. This is very different from the two-part epoxy in a syringe you’d buy at a home center or hardware store. It flows better, and it cures more slowly, so you have more working time. Be sure to carefully follow the manufacturer’s directions for mixing. You’ll probably have bubbles in the resin after you pour it. No problem, we show you how to get rid of those.

Then what?

Once the resin is poured, give it ample time to cure. It cures much more slowly than off-the-shelf epoxy. Once it’s completely cured you can sand it flush with surrounding wood, and admire your work.

Other Uses For Epoxy

In addition to filling knots with epoxy you can use it to fill or bridge other defects. Lots of woodworkers are commonly using epoxy for wood cracks. Again, instead of cutting the defects out, we can make them an interesting part of the finished piece.

General Repairs

If, instead of highlighting defects like cracks, you want them to go away, check out our advice on how to repair wood cracks.

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8 Responses to “Filling Knots with Epoxy”
  1. Mike

    When you are waiting for all the bubbles to rise to the surface, will vibrating the wood help them to come up faster, or will that hinder the process?

    • Customer Service

      Hi Mike. I don’t think agitating the wood would help bring the bubbles to the surface. It takes a while for all the bubbles to come up. You just have to be patient, let them surface, and hit them with heat when they do.


    Nice tech George, have you noticed yellowing over time with this? I have used several two part mixes, and often after several years I see discoloration. Also, were you able to flatten that board?

    • Customer Service

      Hi Robert. I’ve got epoxy patches that are about two years old, with no yellowing. So far, so good…..
      No, I haven’t done any more work with that piece of walnut yet. It’s killing me. I can’t wait to see that amazing board under finish. But there are other priorities.

  3. Jestin

    It is my understanding that it’s not heat that takes out the bubbles, simply exhaling on them also does it. I believe it’s the carbon dioxide that removes the bubbles.

  4. deborareda

    Great instruction video. However, I am surprised you didn’t wear a dust mask or gloves. In my experience the dust, even from casting resin can cause irritation to your skin and thogh there aren’t any noticeable fumes, the fine dust more than likely isn’t healthy to breath. ( also regarding gloves, I always manage to get some on myself, which requires acetone to clean up. 🙂 ). I also use crushed stone or shells to fill large voids.


Tags: epoxy technique, Free Videos, George Vondriska, using epoxy in woodworking, woodworking demos, woodworking skills, woodworking tips