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End checks are a common problem when drying wood. Sometimes they aren’t too destructive and don’t travel too far, but other times they make the end of the lumber completely unusable or make a nice wide board into two not-so-wide boards. These cracks form on the ends of lumber because the ends are drying out faster and shrinking more than the middle. This happens because water can easily and quickly escape out the end, which is the same way it came in, but water trapped in the middle must travel out sideways to escape, which is a much trickier maneuver.
The secret to keeping lumber from checking on the ends is simple and logical – force the ends to dry out at the same speed as the rest of the board, meaning slow down the drying on the ends. Unfortunately, there is no single, 100% effective, way to do this.
The default method for beginners is to paint the ends with latex paint. Latex paint will not stop end checking because it it just too permeable. It will make you feel good, like you are doing something useful, but that’s about it.
Beyond latex paint is wax and unlike latex paint, wax is waterproof. If applied in a thick cohesive film, wax forms a perfect barrier to keep water from moving out of the end of a board. The biggest problem with wax is application. It is just hard to get hot wax on to the end of a lot of lumber in a timely fashion.
The application issue has been addressed by the kids at UC Coatings, who make a product called Anchorseal. Anchorseal is a wax and water emulsion made exclusively for coating the ends of logs and lumber to help prevent end checking. Anchorseal works just as stated, but it isn’t perfect.
First, Anchorseal isn’t cheap. A five gallon bucket goes for about $95. It costs enough that I thoroughly consider whether the wood deserves it. I usually save it for only the best lumber and the species most prone to checking, like white oak. Second, it still takes time to apply, and it is pretty messy. I know several guys that won’t use it in their operations because it gets on the floor and makes everything so slippery that it can be difficult to stand up. Third, using Anchorseal doesn’t guarantee that your wood won’t split. While it will greatly reduce the overall number of end checks, it isn’t uncommon to still get one or two big checks in wide boards. Many pieces of lumber have flaws in them and will split during the drying process no matter how much you try to stop them. Fourth, it must be applied to freshly sawn lumber before the end checks have started to develop for maximum effectiveness.
You can tell from my four points above that I don’t use Anchorseal very often. But, there are places that I will use it, and one is on high-quality, especially thick, flat-sawn white oak. Again, it may not stop all end checking, but it is a great tool to help prevent much of it. On many other species, like poplar, maple, and even walnut, I feel like I usually get by with minimal losses not using Anchorseal. It should be noted that my customers are usually shopping for small quantities of lumber, so they can decide on a board by board basis if an end check is problematic for them. For operations sending out large amounts of lumber to customers that are not picking through each board, using Anchorseal makes the most sense to help produce the greatest amount of useable lumber out of each bunk. At the very least, sealing the ends of the lumber lets your customer know that you did try to prevent end checking.
My greatest gains fighting off end checking have occurred in my sticker selection and placement. While many strides have been made in the industry to produce fluted sticks that reduce sticker stain, very few people have given much thought to using stacking sticks to help reduce end checking.
Awhile back, while at a friend’s sawmill, he casually mentioned how he noticed that lumber will split on the ends, back to the first stick. He was mad that his guys where producing lumber piles that weren’t so neatly stacked, but I focused on the end checking. After that, I paid more attention to my own stacking and changed how I stacked lumber.
The main difference was that I started using the sticks on the ends of the lumber to reduce end checking. I focused on getting the sticks out to the end of the lumber, and I also made sure the end sticks were solid sticks, which help hold in moisture, even on sticker stain prone woods like maple. Since the ends dry out quickly, they don’t sticker stain, and even if they did the loss on the end of the lumber would be minimal. Beyond using solid sticks, I also use wider sticks on the ends, up to 3″ wide. The extra width helps hold in even more moisture and still doesn’t risk staining the ends.
In my opinion, focusing on placing wide, solid sticks at the ends of the boards is as effective as end sealing, especially in relation to cost and time savings. Again, this isn’t a perfect method, but you would be amazed at how well it works to reduce end checking. And, if you have some especially prized lumber, you can rest easy knowing that you can always add AnchorSeal to the mix to double your chances of check-free lumber.
Recently, I got a question from a customer regarding a crack forming in his solid wood countertop. He built the top out of flat sawn white oak lumber and he wanted to figure out what caused the crack and hopefully, how he could repair it. Luckily, the repair is simple (just some glue and clamps), but he really needed to address the cause of the problem or the countertop would most likely crack again.
When he sent me photos of the crack, he also sent me photos of the how he attached it to the cabinets, which was very helpful. The vintage metal cabinets have a bracket in each corner with a hole just large enough for a screw, but not large enough to allow for any movement in the top. In this case, the wood was stuck in place and had no choice but to split when it shrunk in width.
I recommended to simply make the holes in the metal bracket bigger and to add a washer or use a large-headed screw to allow the top to move side to side while still being held down. The secret is to tighten the screws just enough to hold the top in place, but loose enough to allow it to move if the wood starts to pull.
This particular solution was pretty simple, but only because I have seen it many times before, and I knew what caused it. Without understanding how wood moves, the diagnosis wouldn’t be so apparent. Even though most people don’t worry about wood movement as much as I do, I always try to get them to understand the most basic premise, which is that wood moves more in width than it does in length, and you need to allow for that movement.
In woodworking in general, this disparity in movement is referred to as a “cross-grain situation”, when two pieces of wood come together with grain perpendicular to each other, then they want to pull in opposite directions. It happens all of the time in furniture construction, and it must be addressed to avoid catastrophic failures. In the example above, the setup was the same as a cross grain situation because the metal cabinet will not change in any dimension, while the wood moves in width.
When attaching wood tops of any kind, whether it be a wood countertop to a cabinet or a table top to a table base, you need to allow the top to move or it can split. The good news is that there is more than one way to attach a top and still make allowances for this movement.
The first and most common way, as mentioned earlier, is to make an oversized or elongated hole and to make up any differences with a washer or large-headed screw. Assume that any problems will be caused by excessive shrinkage and make sure that your holes are big enough and that your screws are placed in the holes so that the top has room to shrink.
Another method, which I like to use on tables, is to make blocks to fit into dados on the insides of the aprons. They don’t take too long to make and can easily be added wherever necessary. The blocks should be made so that tightening up the screws will just pull the top snug, like a perfect fitting tongue and groove joint and placed with a little separation to make sure nothing binds. They work great, and I think they look great too.
When attaching a top with a propensity to move, understand that all of your attachment points don’t have to have play in them. For example, you can firmly attach a countertop to the front of a cabinet as long as you allow the top to move in the back. Or, on table tops, you might choose to firmly attached the top in the middle of the width and allow the outside edges to move. This is perfectly acceptable and keeps the top centered on the base.
The main point to remember through all of this is to allow the wood to move. You can only really cause a problem if you don’t allow it to move. And remember , if you find that it is moving too much for your liking you can always go back and firm things up once you understand the potential problems.
For a more thorough description of wood movement click on these two earlier posts Have Your Heard About Shrinkage? or Why Quartersawn Lumber is so Stable: The 0-1-2 Rule In Action, to read a link on the subject. I think it is probably the most important subject for any woodworker to fully understand.
I am a woodworker, and as a woodworker I live by a certain set of norms which dictate that I be accurate, but not ridiculously accurate. After all, wood changes size all of the time, so there is a limit to how accurate we can be and how much we should really worry about it. For most of us, a few measurements in a job are critical and the rest of the pieces are fit to look good. We may use measurements as a jumping off point, but it isn’t uncommon to trim a bit here and plane a bit there.
When I am in the shop, I always have a tape measure hanging off of my pocket for anything that needs to be measured. I use it a lot, but mostly for rough measurements, like making sure a piece of wood will be big enough for what I have in mind. I also use it for more critical measurements, but I try my best to find ways to not use measurements when things start to get critical. For example, instead of measuring, I will use a scrap piece of wood as a spacer. That way I don’t need to worry every time about reading the tape measure wrong, and I know that all of my spacing will be very consistent.
As much as I try to avoid being fussy about my measurements, sometimes they need to be a little more accurate. One of the tools where accuracy is important is the planer. If I want 1″ thick wood, I want to know that it is 1″. Now, more engineery people might reach for their calipers, but for those of you like me, with only a tape measures on your belt, I have a very accurate way to make perfectly sized parts – just stack them up.
Here’s the logic. If your measurements are just slightly off, you may not notice it in just one piece, but as you add up the pieces you also add up the differences and they become much more obvious. Just run a scrap piece of wood through the planer, chop it into 3, 4 or 5 pieces, stack them up and measure them. 5 pieces of wood that are 1″ thick should measure 5″ – simple de dimple. If your 1″ thick board isn’t exactly 1″ thick, you will see it, even without calipers, and then you can adjust the thickness.
The beauty of this system is two-fold. First off, you don’t need to worry about having calipers (after all, those are for kids that work at Boeing and have really clean floors). Second, it gives you a more accurate real-world reading of what is coming out of your machine. We all know that a board coming out of the planer has dips and doodles in the wood and can range in thickness depending on the spot that you measure. Adding up several pieces of wood gives you not only a measurement that is accurate, but it is also closer to the average. We are only talking small amounts here, but if you are setting up to plane a bunch of lumber, it is great to know what the bulk of it is going to measure.
I use this system to double-check measurements on other tools as well. It works great on the table saw to make sure that your 3″ wide board is really 3″. Instead of cutting just one sample board 3″ wide and determining that it looks really close, cut 3 or more and add them up. Assuming that you can do a little simple math, you will be able to tell if the 3″ mark is consistently spitting out 3″ boards and not 2-63/64″ boards.
When using my fancy measuring shortcut, there is one important rule to follow. Make sure the tongue on your tape measure is accurate or don’t use the tongue at all. If you don’t trust the tongue on your tape measure then take a reading starting at the 1″ mark to check the distance and then just subtract 1″ from your reading (and then hope that a holiday is quickly approaching that might lend itself to the arrival of a new tape measure).