George Vondriska

Filling Knots with Epoxy

George Vondriska
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Duration:   9  mins

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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17 Responses to “Filling Knots with Epoxy”

  1. chip Weseloh

    The ad for casting resin says it dries white. When filling a knot hole, wouldn't you want it to dry when you sand it flush, you can see the knot/imperfection through the resin? I'm confused by that description of it drying white????

  2. Steven Larson

    <strong> Ticket 36955</strong> In the epoxy Woodworking class they mentioned using penetrating epoxy to avoid leaching. George didn't use it in this video. Is it necessary or does the casting resign just not leach?

  3. Ivan

    George, I watched your video and since I want you to live longer. I wanted to recommend that you wear a mask when sanding. The dust on your glasses is a definite indicator of the dust your breathing. As you are aware, that's "No Bueno". Take care and as always, I love your knowledge and teaching skills.

  4. Timothy Lee Russell

    Great overview, thanks! !!! BUT !!! Use an appropriate respirator...inhaling saw dust and finely ground epoxy is very bad for you.

  5. Regina Campuzano

    Smooth vibration does make all the bubbles come out. I used it for doing dummies, works great. Also mixing delicately with a round stick.

  6. Georgia Davison

    Considering how much dust was on your glasses and shirt, sanding WALNUT and EPOXY, meant you SHOULD have worn a DUST MASK!!!

  7. Michael Strong

    Hi , before sanding the resin would running a planing router over it be advisable?

  8. walt

    whoa! do you not have lung cancer in the States? i really dont think its a good idea to encourage people to sand epoxy [or some woods' for that matter] without first instructing them of the potential health risks of inhaling this fine dust. i work with epoxy all the time and would never-ever sand without an efficient extraction system &amp; wearing a fine filter mask. In fact, if there is still evidence of dust on cloths or hair, climb into the shower and wet it down - then take off the mask! You point out the dust on your spectacles, so imagine what you were pulling in to your lungs with every breath whilst sanding this blank - not a wise course with epoxy dust. In my professional opinion you should remove this video (which is otherwise very instructional) pdq and replace it with a healthier version. Further: 'guess-gauging' epoxy mix quantities is also very bad practice &amp; to be honest just plain lazy. For best results the manufacturer gives precise ratio's for a reason; it isnt guess work and can be dangerous [if you've ever seen a student over do the catalyst causing the pot, first to boil, and then ignite, it isnt a joke i can tell you!] Work-safe, Stay-safe :-) walt, wales uk

  9. John Whiting

    Hey George, How bout running it through the DeWalt Thickness Planner? After plenty of cure time!

  10. John

    Great video, Mike. What types of dye should I use if I want to add some color to the epoxy?, If there are still voids in the board after the epoxy sets up can I simply pour on more epoxy and wait another day for it to set or will I need to rough it up somehow to get it to bond? Also, are there any issues with running the boards containing epoxy fill through my planer?

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