Recently purchased a bunch of 6/4 black walnut to use for a long built-in counter-top… which will be about 115″ x 24.75. All the boards are pretty good, but I’m running into an issue with a knot in one of them. Specifically how soft part of the knot is…
If you look at the attached photo you’ll see there’s a dark and light side to the knot. The light side has the consistency of cork in the middle, getting progressively harder the farther out from the center you go. I used a needle to probe the knot (a needle can be pushed into the lighter part of the knot) and while depth varied it extends about 1/3″ into the piece.
How should I deal with this? I’d been planning to use either black epoxy or black CA with sawdust to blend the knot before staining the board. However, I’m now concerned about how soft that part of the knot is… it’s not soft enough that you can push your finger into it, but it is very slightly spongy to a hard press.
Is it fine to just seal this with black epoxy or black ca? Or do I need to actually dig out the softer stuff and then fill the whole knot with something? Note that flipping the board doesn’t really work… all of the boards (4) have one side that’s largely heart wood and one that’s sap, and the knot is on the heartwood side.
Thanks in advance for any advice!
-Rick
Replies
You can get an epoxy product that is made for stabilizing wood. It is thin enough to be absorbed by soft wood like that and then become solid. Or, you could just chisel out the soft wood and fill the hole with epoxy. Either will work.
Thanks for the reply! I'd rather avoid chiseling out the knot since the resulting hold will be large (at least 1.5" and about 0.3" deep). So, I'm looking to repair it if I can.
I think you're talking about the types of penetrating epoxy typically used for repairing rotting/weak wood on boats? What about a good CA glue... like Starbond EM-150. Is that too thick? CA glue is pretty runny... would it be strong enough if I saturate the knot with it?
-rt
I use epoxy mixed with carbon black powder, I also heat the epoxy with a heat gun before the fill and after so it becomes thin as water. It’s makes things easier to tape just outside of the knot say with an octogonal shape and fill until it’s flush with the masking tape so you get it even or above the surface in one shot.
Epoxy or CA will work. Color it if you want it darker. I'd probably do several thin coats of CA first, just to soak in to the punky part.
Minwax Wood Hardener is probably the most widely available of the soak-in products designed for this purpose. I've found it very effective, and it's also handy for spongy window sills, etc.
I'm only going to add advice to mix the epoxy very thoroughly.
I've had good results with araldite mixed with carbon black. It's heart-breaking if it won't set because I got lazy on the mixing...
wood resin epoxy,turns rot into wood. A brand I use is called Smiths, I've tried other products but they've all been bunk! Takes a few days to fully cure and that's on purpose so that it absorbs deep into the wood.
Howdy all. For anyone who's interested, I finally finished up the knot hole fix I posted about... still working on actually finishing the countertop.
To summarize, I decided to implement the knot hole replacement idea. I had a similar knot in some scrap from the project, so I routed the hole in the counter, cut the knot from the scrap to fit, and then glued it in and planed/sanded flat. Photo of the outcome pre-stain is below, came out really well!
This was my first time doing something like this. One suggestion for anyone else doing this is to cut the fill first, then trace that with an exacto knife over the spot you'll router out. I found someone who did this on Youtube after I'd completed my project, and it definitely seems easier. I used a template for both my hole and the filler, and while it was close there was a lot of small trimming and sanding to get it to fit exactly right. Tracing the fill would have eliminated a step in the chain (and the small errors that go with it.
Thanks again for all the help!
Best,
Rick
Looks good.
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