Dealing with Defects
“Every little defect gets respect.”
If you’ve been a woodworker for longer than ten minutes, you’ve likely run across them. You’ve seen those boards at the lumberyard; the ones marked down in price, languishing away in a forgotten, dusty corner of the racks. The price catches your eye, but as you look closer, you see why they’ve been discounted- there’s something wrong with these sticks. They’ve got knots. Cracks. Checking. Bark inclusions. They’re twisted. Warped. Or even a touch of rot. In short, they’re not clear boards, or even FAS boards. They’re the uglies. Defects.
This article is going to go through some of the more common types of defects, and more importantly, how to deal with them. Of course, your tastes may vary; I get plenty of customers who are looking for the most solid, clean and perfect piece of wood they can find. Those customers also tend to wait a lot longer for what they’re looking for, on average. Unless you got your wood from one of the big box stores (whose focus is on homogeneity, among other things), chances are good that your chosen piece has at least one not-so-perfect thing about it. Of course, you can just cut around it- but that leads to a lot more waste, which is never good. Hopefully by investing in some basic tools (most of which you probably already have), you can save a board destined to be firewood.
There’s a few different types of defects you can come across in a piece of wood. Aside from a warp or twist in a piece, which can be fixed by milling it, the more common are:
- Knots – where the tree had a branchout, typically now cracked (or in some cases, totally missing, resulting in a knothole)
- Checking – cracks along the wood grain, caused by stress in the wood or uneven drying
- Bark inclusions – pockets of bark in a board
- Bug holes & tracks – usually found in sap wood, small holes or “tunnel” cross-sections
- Rot – soft, spongy-feeling areas in a piece of wood caused by bugs, fungi or bacteria
Now, I know what you’re thinking. “Epoxy will fix all those things, you clown. Why are you writing an entire article about this?” And yes, that’s true. You could use epoxy to fill all these. Here’s the thing, though. Anybody could do that. I’m going to steer clear of using epoxy as much as I can, because even though it may be the easiest solution to a defect, when has the easiest fix been the most fun? Besides, using other, contrasting materials in wood can give you some beautiful results. So let’s go through the list!
Knots. Knots and knotholes are some of the easier defects to deal with, as they’re usually just a small crack surrounded by the rest of the contiguous wood grain. At worst, they’re a clean hole right through the board. Instead of filling it with epoxy, consider this: scribe a small shape that contains the knot- could be a simple square, circle, whatever. Then take a palm router and rout out that shape, and patch it with another piece of wood- could be the same species, could be a contrasting one, it could even be a different material such as a soft metal like brass or aluminum. Patch that knot, and turn a bug into a feature!
Checking. For checking, bowties (or butterflies, or Dutchmen, etc.) are the traditional way to go, and for good reason. They’re a mechanically strong reinforcement that will stop a check from traveling further along the wood grain- and they’re a classically beautiful design element, as well. Same procedure applies here as it did for patching a knot, although the order is different. Make a bowtie, trace the shape over the offending check, rout it out and glue in the patch. For any gaps left over, just rub some sawdust and wood glue into them. Once it dries and you start sanding, it’ll look perfect.
Bark inclusions. There are a few different ways to deal with bark inclusions, and it will really depend on your personal aesthetic. No matter what you do, though, step one should be: CLEAR OUT ALL THE BARK. Why? Because the bark (or the outside) of a tree absorbs and releases moisture at a different rate than the wood inside it. If you leave bark in an inclusion, it will dry out faster than what it’s attached to. This means the bark will loosen over time and could ruin your piece. So what are some ways to address bark inclusions? Again, the patch method works well, especially if you need your surface to be contiguous and without holes. If you don’t, why not just sand it smooth? Unevenness in the surface of a piece is a great way to add visual interest. I’ve also seen videos of people using molten metal in the place of an epoxy to fill voids- I’m not exactly suggesting you do this, but it did look really cool.
Bug holes and tracks. Bug holes have to be one of the more irritating things to try and fix in a piece of “imperfect” wood. They’re usually just small enough to be noticed, and there always seems to be a gazillion of them. And just when you think you’ve got them all, you always find one more, don’t you? Sometimes the air compressor just won’t get all the sawdust out; you’ve got to get in there with a metal pick and dig it out by hand. So once you’ve cleared everything out, you could try and use epoxy to fill all those tiny holes, painstakingly applying it with a toothpick or something and then hitting it with a blowtorch or heat gun to thin it out so it’ll flow into all the holes. Instead, you could just try a product like Starbond’s Black CA glue- it wicks into small holes and cracks like regular CA glue, and once it’s dry, remains black and ready to be sanded. We’ve started using this stuff in the shop here at Goby, and everyone became an instant fan.
Rot. Wood rot is one of those things that really test your skills as a woodworker. Do you cut it out? Do you try to fix it? Do you just turn that piece into firewood? Luckily, you’re not without options. And this is the only trick in this article that actually explicitly calls for epoxy. Once you’ve got your epoxy mixed up, add just a little bit of acetone to it. Then pour your thinned-out goop into your punky area. (Make sure to test this method on a scrap piece first. A little will thin it out; too much will keep it from fully curing.) The idea here is the same as the “stabilizers” woodturners use for punky or fragile pieces, such as burl chunks. You can also buy commercial versions of this, although chances are good you’ve already got both epoxy and acetone in your shop. Once you’ve poured your mixture into your rot spot, let it cure for at least 72 hours. Repeat as necessary.
Defects don’t have to mean that a piece of wood is now an unusable chunk of firewood. If you’re willing to work with it, an imperfection can turn into a focal point in your final product. So the next time you’re out at the lumberyard, why not give that “rejects” pile a second look? You just might surprise yourself with what you’re capable of!