epoxy for knot holes?

[alex grams]

I am working on on larger pieces of walnut with a couple of knot holes (<1" Diameter) I need to clean out and fill.

I have some west system epoxy 105 (though it is at least 4 years on the shelf). Is this an acceptable epoxy for this task.

I read on west's website that with a good seal it should still be good for many years, though the hardener may darken some with aging and the epoxy resin may thicken/crystalize some and to heat to 125 degrees to redissolve the crystals (anyone run into these problems?)

If it is not the proper type, what epoxy's do you recommend? And for tinting the epoxy (the wood is walnut) Just get some walnut sawdust and mix in with the epoxy to match the colors?

Thanks in advance.

[Bill McDermott]

I can't speak for the integrity of aged epoxy. But it strikes me as a low risk application. Maybe a good way to use up old epoxy.

Anyway, as for filling holes... yes and yes. Sawdust mixture works. I regularly put a drop of TransTint in the epoxy mix. That works very well. Overfill it then use a card scraper and regular sanding. You are going to like this.

Why not experiment on scrap?

[Joe Angrisani]

.....Why not experiment on scrap?

Yes yes yes. :)

And tint it as Bill said. Otherwise the glue itself will look way too light on walnut.

[John Coloccia]

I don't know about other epoxy in general (though it applies) but I've never known West to go bad, even after many years of sitting on a shelf. Yes, the hardener does get a little darker.

[alex grams]

I will certainly be testing on some scrap first, but didn't want to waste efforts if the epoxy wasn't going to do the job and i needed to get another type.

[Kyle Iwamoto]

I just filled some voids with epoxy and artist's oil paint (not acrylic or water based artist oils, they won't mix with the epoxy). You can use colors for accents or black. It's NOT a "natural" thing to look at, just some out of the box thoughts. I've used sawdust/wood chips with very good results.

[matt tennessen]

My preference is to mix a little bit of very finely ground dark roast coffee on the first pass and the epoxy alone for the inevitable second round (if it's a large knot). Because knots are so much darker, I find that just sawdust looks too light and looks more like a patch. But if the knot is deep, either way you'll probably want to use something mixed with the epoxy. Sometimes it dries cloudy if it's too thick.

[Larry Edgerton]

My preference is to mix a little bit of very finely ground dark roast coffee on the first pass and the epoxy alone for the inevitable second round (if it's a large knot). Because knots are so much darker, I find that just sawdust looks too light and looks more like a patch. But if the knot is deep, either way you'll probably want to use something mixed with the epoxy. Sometimes it dries cloudy if it's too thick.

I like that idea, i will have to try it. I too do not think sawdust is the way to go, looks like a patch as you said.

What I do in the case of a through knot is tape the side that will be inside, pour in epoxy to within about 3/16", get the bobbles out with a torch, and wait. When that is cured I use oil paints to make a knot on the epoxy, let it dry and fill the last 3/16", again chasing the bubbles with a torch. This makes it look like a knot but because the paint is deep in does not look painted. Finish as normal.

I have not ever had West System go bad either. 107 may be the prefered hardener if this project is going to be in direct sunlight, but if not 105 will be fine. You can always call West System Tech line if in doubt. 1-866-937-8797

Larry

[Bob Direso]

I have used epoxy and transtint with ok results in the past. My latest approach was to use walnut shavings and if available knot material to fill the knot hole using CA glue to bind the shavings into the void. After filling the knot hole slightly beyond the surface with shavings I use a sanding block to level the material and I add a few drops of CA glue into the sawdust created by the sanding. The end result looks much more natural in my opinion than colored epoxy. Good luck whatever way you go. Bob.

[Jim Finn]

I have filled in voids in wood using a thin epoxy called "Z-Poxy" mixed with crushed and powdered, colored chalk from the dollar store. Gives a nice contrasting accent. I used blue in Mesquite.

[Bob Deroeck]

[QUOTE=I read on west's website that with a good seal it should still be good for many years, though the hardener may darken some with aging and the epoxy resin may thicken/crystalize some and to heat to 125 degrees to redissolve the crystals (anyone run into these problems?).[/QUOTE]

I've experienced both of these problems, typically with West 205 hardener over 2 years old and West 105 epoxy resin over 4 years old. West's website is correct. While the hardener may have darkened, it still performs as well or close to fresh hardener. And, thickened/crystalized resin can be resusitated by heating it to about 125 F.

[Frank Drew]

My hardener darkened quite a bit, to the point where you wouldn't need to color it to match a finished walnut knothole. I never noticed and degradation in the product, though, and this was after a good decade and more sitting in my shop.

[Mike Monroe]

Speaking of knots and epoxy... anyone ever use a dab of artist oil paint to color the epoxy? I wonder if the linseed oil binder in the artist oil paint would mess up the hardening of the epoxy. I don't have any Transtint on hand, just some Winsor & Newton artist oils.

[matt tennessen]

I've never used a torch for the air bubbles! I'd like to try that. Just direct flame on the just-poured epoxy? I'm assuming you've got to be careful not to create new problems to fix what with an open flame and wood combination.

[Mike Hollingsworth]

Speaking of knots and epoxy... anyone ever use a dab of artist oil paint to color the epoxy? I wonder if the linseed oil binder in the artist oil paint would mess up the hardening of the epoxy. I don't have any Transtint on hand, just some Winsor & Newton artist oils.

That's what I use. Never had a problem.

[Darrin Vanden Bosch]

I have used epoxy to fill voids , cracks and knots, I do not clean the knot out.I use a long curing mix that is runny and it will seep in and fill all the voids. Just leave it a little proud of whatever you are filling, then scrape and sand to level. Oh and I don't use any coloring or sawdust at all, I just don't see the point.
Darrin

[David Helm]

My preference is to mix a little bit of very finely ground dark roast coffee on the first pass and the epoxy alone for the inevitable second round (if it's a large knot). Because knots are so much darker, I find that just sawdust looks too light and looks more like a patch. But if the knot is deep, either way you'll probably want to use something mixed with the epoxy. Sometimes it dries cloudy if it's too thick.

My experience is that the epoxy ends up darker even than the knot. My favorite method is to use sanding flour from the wood in question. The shade always matches the wood.

[David Gandy]

Epoxy is a good filler for wood. I just filled a 12/4 slab of walnut that had a couple of big knots and mixed in powdered graphite to get a jet black color. Used a block plane to take the majority of the buildup down and a card scraper to finish. I think I saw Norm do this on a mesquite project he was working several years ago.
David G

[Butch Butler]

How would a set of planer blades fare to clean up and level the fill?......Not something thats done every day, so not a regular punishment on the blades.....on the flipside, how does the 105 epoxy react to being planed? Thanks, Butch

[David Gandy]

How would a set of planer blades fare to clean up and level the fill?......Not something thats done every day, so not a regular punishment on the blades.....on the flipside, how does the 105 epoxy react to being planed? Thanks, Butch

I have not planed a board after having filled with epoxy but I watched a New Yankee Workshop episode where norm did it with his Delta planer. Don't know if this affects the blades negatively or not....course, Norm probably has a roadie to work on his tools. I would speculate that it would not have a great impact on the blades, however, I have ran a painted board over my jointer and paint is very hard on HSS jointer blades, that I can testify.
David G