Filling Voids, Cracks, and Defects in Wood with Epoxy - Ask Matt #19

I like to incorporate some goofy pieces of wood into my work. Many of them have structural issues or voids that need to be addressed before they can be used in a project. Epoxy works great for filling and stabilizing knots, cracks, voids, and other defects in wood.

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[MichaelMakesMistakes]

I use a ton of epoxy as filler, since I use a lot of wood from locally felled trees. I know this is a little anal-retentive, but I always stir the epoxy in two cups. A few times when I was mixing in one cup before pouring, I would get a pocket of unmixed epoxy...probably from the edges or bottom of the cup. So now I mix for one minute in one cup, then pour into a second cup, and mix for another minute, with a new stir-stick. Works every time.

Also, if you ever get neurotic about bubbles, get a vacuum chamber to degas the epoxy...works like a charm.

[jamesdesmond]

Filling cracks etc with epoxy resin has been a big question mark for me as I start wood working in my new, now retired, work shop. Thanks! Matt, this was a big help; great video.

[RossNanfito]

The absolute best explanation of epoxy for voids and cracks. I'd already gone through this learning curve the hard way, wish I'd seen this 6 months ago. I also use West Systems. I also like to incorporate cracks and knots and voids. Thanks for making the time to do these videos.

[kevinl.]

Great video. One thing I learned was to watch the amount of epoxy going in the crack. This keeps the overflow stain area to a minimum 👍

[kennethkish]

Hi Matt, on large thick lumber I use my shop vac to suck the epoxy through the cracks. I use a thicker mix of epoxy. Once the mix comes out the other side I shut off the vac, tape and continue to to fill with thinner mix epoxy. I enjoy your videos and watch as often as i can. Thanks for sharing.

[Triassic]

Thanks Matt! This was very helpful. I am working with my first live edge slab to make a countertop for my son's bathroom countertop. I had no big voids, but there were enough cracks that made me nervous about the moisture and waterspills in a bathroom. I tried shopping for wood fillers and epoxy prior to seeing your video....to no avail!!! I was quite happy when I ran across your video giving recommendations for the product, and very detailed instructions on how to use it. I have just finished the epoxy work, and now I will be putting on my first coat of waterlox on the underside. I am very excited!! Thank you from a project loving mama!!!

[jonwikan]

I really like your videos and have been using some of your tips but I might add a tip, although even many experts use pigment in epoxy for defects, holes etc... I have a rule with epoxy. Never ever ever ever use tints for knot holes or cracks; unless for some odd reason the knot is not the color of a knot inside the hole, or if the hole is bigger and light can shine through the other side(almost never). Epoxy without tint will mimic the color below it and look absolutely perfect when sanded and varnished. Adding tint looks artificial and stains the adjacent wood. Adding sawdust looks pretty lame too. If whatever hole you are filling is the color of the wood or hole fill it with clear epoxy. When pigment is used in epoxy the deeper the hole the darker the color becomes. When to use pigment? say you laminate a table with strips of wood and your glue line has a half knot. Then you can gouge the non knot side out to look like a knot. Paint it with acrylic or epoxy and pigment and then fill after dry with clear epoxy. Remember epoxy gets darker with depth. Cracks that go deep will appear black with just clear epoxy poured in so no need to color dark. Knot holes become black with clear epoxy. Shallow dings or tear out etc...mimic the color below(wood) if (nearly) clear epoxy is used. Reach out and I can show you examples and I have literally almost a thousand knot holes, cracks etc I can snap a pic of for you all; and remember epoxy blushes, so if you have to pour more after it cures to fill that dam knot hole that was so thirsty. Make sure you wash the patch with hot soapy water and say a white scotch brite pad to remove the water soluble amine blush before lightly sanding and pouring a second coat. Same with after a perfect epoxy patch. Hot soapy water before varnish. Epoxy won't bond to it's own blush very well and either will varnish. Cheers, Jon

[hvrtguys]

For knots I grind dry coffee beans to dust then mix up small batches of 5 min epoxy. After the epoxy is mixed I add enough coffee powder to get a stiff mix like cookie dough. Then I use a putty knife to fill the cracks. While the mix is still a bit green I will remove excess filler with a sharp chisel. I have found that you cannot simply add the three components together all at once and then mix as it doesn't harden properly.

[DreadKnotWoodshop]

I have tried this technique and it works very well. I really like the way projects look when you leave the defects in in your material. It was also awesome to see my sticker in your cabinet!

[derekvanderhorst]

I live on the west coast and have been working with a lot of salvaged old growth redwoood in the process of restoring my 1880s home. I use all the techniques you show in this video with one key change. Applying the epoxy precisely out of a mixing cup is next to impossible. I dispense the resin and hardener into the corner of a ziplock or other hole-free baggie. Twist the baggie to isolate the corner and squish it around to mix. Cut the corner off with a razor knife at whatever size stream you need. Keep twisting the bag to keep it sealed and build a little pressure. I use recycled bags but u run the risk of having a leak which is a mess.

[paulbuckeljr]

Excellent timing Matt! I'm getting ready to fill silver maple crotch and this will be my first time using epoxy. Thanks.

[TickyMN]

The board you used looks just like some I have and thought they would become firewood. I may invest in the West System to save them and add interest to my projects too. Thanks Matt!

[randykniebes]

Thank you Matt for a great array of application of I am a bowl turner that likes very interesting bowl with voids and Wanting to fill the voids of an inclusion, so people won't say that it is cracked, no good!!! Now I know how to fill those unique voids and show the great character of the bowl's great grain patterns....

[darrenswoodworks]

I'm relatively new to epoxy, and am looking forward to doing a few projects with epoxy. Thanks for the great in-depth explanation of your epoxy experience.

[randykniebes]

thanks again for your instruction on epoxy in order to use wood that I know I have thrown into the camp fire pit.... Even though many time the wood has some very beautiful figured parts near the knot or crack... and by you adding the epoxy, you just end up with an attractive knot and the cracks are unique as well, especially in ash, cherry, and Thanks again for showing me how to use epoxy to figured wood....

[LynnLaceyLLWW]

Well done - I've used epoxy for years filling Mesquite cracks and checks and it just adds to beauty of the wood. Thanks

[blissjunkie]

Thanks Matt. This couldn't have come at a better time. Have some black walnut 8/4 I'm going to bookmatch for some door and drawer fronts and it had a few knots in it. Went with the 206 and some black walnut transtint. worked well.

Tip: when the mix starts to whisp smoke...You're done...or about to be.

[katzmosestools]

just bought the pieces to the kit using the affiliate links in the description. Somehow it's $30ish cheaper than the actual "kit" on Amazon. Cremona with the win!

[judithfairchild]

I like the way you keep the epoxy in normal wood colors. Thank you for the explanation

[jamesopell]

Great video on using epoxy. This technique can make defective wood a useable product and is quite attractive. Thanks for sharing Matt...