Round Cut Tops (Almost) Always Split

All wood splits, some more than others, but it all splits. It even splits when paid professionals try to make it not split. This is good news for those of you wanting to snuggle by a warm fire, but not such good news for connoisseurs of  split-free wood. And, it is especially bad news for anyone wanting to make a round table top out of a slice of tree.

It seems easy enough to just slice a cookie, or coin, or round, or whatever you want to call it, off the end of a log and use it as a table top, but it rarely works out. The problem (especially when swimming) is shrinkage, and in the wood realm it’s uneven and unproportional shrinkage.

I talk to customers a lot about this uncomfortable subject, and even though it isn’t pleasant, someone has to do it. As woodworkers, it is critical to understand how wood shrinks (read an earlier post about shrinkage by clicking here), and as customers it is important to understand the limitations of wood.

Drying quartersawn lumber is easy, relatively speaking, and almost always produces wood that doesn’t split. Drying flatsawn lumber without splits is more difficult, but if the ends are sealed and the lumber is dried at a slow, consistent pace, it can be done reliably. Drying round cuts from the end of a log, however, is a totally different story, and almost always results in split wood, and not just a small split, but usually large, unsightly, unrepairable and often devastating splits. So much so, that I tell customers I will cut rounds for them only if they take the milled pieces directly from my sawmill as soon as they are cut. That way I can prove that I had nothing to do with them falling apart – they do that all on their own.

It all goes back to the way wood shrinks and the way it does so unevenly. As wood dries, it shrinks twice as much with the rings as it does from the center. When viewing a log at the end (not a round cut off the end of a log but an actual log), this produces cracks that resemble spokes in a wheel. Sometimes there are larger cracks mixed in with the smaller ones, but they are always in multiples. The end wood wants to split, but since it is attached to a log which is holding it in place, the end cracks with many smaller splits to even out the pressure.

When still attached to the log there will be many smaller splits.

When still attached to the log there will be many smaller splits.

If that piece is cut from the end of a log all bets are off. There is no log holding things together, so the end result is usually one large split that relieves all of the pressure at once. With wood that is known to split easily, like oak, the round cuts will not only have large splits, but will often just break in two or more pieces.

Here are some examples of dried wood cookies. All of these were cut from the end of the log when the wood was wet and then air dried slowly in the shop. They are all about 18″ in diameter and 2″ thick.

Walnut-Cracked!

Walnut-Cracked!

Pine-Split!

Pine-Split!

Maple-Busted!

Maple-Busted!

What's this! No crack? Every now and then they don't crack. This walnut is half the diameter of the others.

What’s this! No crack? Every now and then they don’t crack. This walnut is half the diameter of the others.

So, now you know that the cool round table that you were planning to build is probably going to split if you do nothing about it, but can you do something about it? Well, maybe, kinda, sorta.

One way I know to work, from personal experience and from other local sawyers, is to cut the rounds at an angle. This will reduce or completely eliminate the cracks because the stress is going more up and down than in a circle, but it will turn your round table top into an ellipse. And, while a piece that stays together is probably better than a piece that falls apart, an ellipse is not always acceptable. I personally expect to see a round piece of wood when you tell me it was cut from the end of a round log, and find the ellipse shape a bit unnatural.

This slice (from roxyheartvintage.com) was cut on an angle so it wouldn't crack. The angle cut is evident on the outside edge and by the fact that the "round" is not round. Logs that start out round, will end up as an ellipse angled slice.

This slice (from roxyheartvintage.com) was cut on an angle so it wouldn’t crack. The angle cut is evident on the outside edge and by the fact that the “round” is not round. Logs that start out round, will end up as an ellipse angled slice.

Another alternative is to remove the pith (center of the log). Removing the pith can stop the devastating splits, but it obviously puts a hole in the piece of wood, and it is still a gamble because it is hard to tell from tree to tree how much pith needs to be removed to stop the splits from happening. A larger hole is better, but at some point the missing wood in the center will demand creativity, and perhaps more wood or glass to make a complete top.

The last and most widely used solution is to use a wood stabilizer like Pentacryl or PEG (polyethylene glycol). Originally developed to stabilize wood from archeological sites, Pentacryl works well to stabilize all kinds of wood from punky wood to crotches and will help with wood cookies. It works by replacing the water in the wood and keeping the cells at their original size, even when dry. Know that while Pentacryl will reduce and often eliminate cracks, wood cookies are by far the most difficult to dry and may still crack.

Pentacryl is a good option to keep wood cookies from cracking.

Pentacryl is a good option to keep wood cookies from cracking.

Pentacryl is not perfect. It works well, but it is expensive at $60 per gallon and adds a yellow tint to the finished piece. And, wood cookies which could normally be dried relatively quickly need to be dried extremely slowly. So slow, in fact, that thicker pieces could still take over a year to safely dry.

PEG is applied like Pentacryl, but has drawbacks that make it less than perfect too. Like Pentacryl, it is also expensive and the resulting wood surface may not accept the finish of your choice. It also takes extra time to apply and may require additional equipment to make it work correctly.

The bottom line is that you can make a table out of a round end cut from a log, but you’ve got to be prepared for failure and/or be prepared to throw plenty of time and money at the problem. I still steer away from cutting wood cookies and do my best to direct customers away from them as well. And, if I do end up cutting wood cookies for a customer, I literally cut and run.

 

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About wunderwoods

Hi! My name is Scott Wunder and I am the owner of WunderWoods Custom Woodworking. We build wine cellars, built-ins and furniture from local woods, here in St. Louis, MO. Recently, I finished a three-year term as the President of the St. Louis Woodworkers Guild, which had me writing a monthly article for our newsletter. I love to write, especially about wood, and found that I still had more to say. Every day I run into something wood related that I realize some of my customers don't know and this seems like a great forum for sharing what I have learned (instead of telling the same story to each person). The main thing to remember is that I try to keep it light and as my wife always reminds people that have just met me, "He is joking."

39 responses to “Round Cut Tops (Almost) Always Split”

  1. David Gendron says :

    Good evening, interesting topic. I have a cutting board, made by those guys; http://boardsbyjoel.com/hardwoodRounds.htm
    What do you think is there process??

    Cheers
    David

  2. Bob Portman says :

    I was wondering if it would help to carefully 1/4 the cut end thru the middle (pie cuts), let it dry and then clean up the cut edges and “reassemble” the round. I know that even with thin kerf cut it would be hard to realign the grain- but it might give a stable result. Any ideas?

    • wunderwoods says :

      Reassembling pieces after they are dry will work, since most of the shrinkage happens during the initial drying. It will require two pieces that match that can be split before drying and then machined and reassembled after drying. The results can be more than satisfactory, but still a lot of work for what everyone assumes is just one cut.

  3. Ariel says :

    I have a question I hope you can help me with: I just cut down a 60 foot silver maple in my backyard and retained seven 6 foot logs that I hope to use for landscaping. I’m wondering what I should do to avoid them splitting/ cracking. This wood will just be used as logs in the backyard. So would coating the ends with Thompson’s water seal be a good idea or something like that?

    • wunderwoods says :

      I don’t think anything will help. Silver maple logs will not last long outside. Within a couple of years you will see significant degrade, especially with ground contact. Sealing them doesn’t help because they are already wet on the inside and sealing them just traps in the water.

      • Ariel G. says :

        This is really helpful. So, can you paint a picture of what “degrade” looks like? Will the logs mostly get big cracks ,or the wood start decomposing on the outside? (Or completely fall apart?)
        My thought was have the logs rest just above the ground (putting a couple notched logs underneath), as well as cut a bunch of different height stumps (sitting on the ground) that could create “stairs” or sitting areas, creating a kind of kid-friendly space for playing, climbing, hanging around.
        I’m curious now what’s likely to happen to the logs. BTW, I live in the Chicago area, so we have cold winters and hot n humid summers…
        Thanks for this–this knowledge you’re sharing is very much appreciated…

      • wunderwoods says :

        Cracks will happen no matter what. The degrade will be the wood decomposing and falling apart. Even white oak and walnut logs, both known for durability will start to degrade on the outside in a similar time frame. They will last longer if you can get them dry and keep them dry.The logs need minimal ground contact and the bark should be removed. The bark holds in water and promotes the decay. If you can do both of those things, the logs will last for much longer.

  4. Jack Fouracre says :

    Hi!

    Lovely article, very educational!

    Quick question, I have some 5″ thick, 16″ diameter black walnut cookies that have been air drying outside for about 6 months (winter here in Toronto). Basically I am going to resaw them to about 2.5″ thick but I would like the to crack exactly like the picture above. Repeat, I want them to crack 🙂 I was thinking I could maybe add a slit with a hack saw to try and induce it?

    Hope you find the time to respond! Cheers!

  5. Andrew says :

    I have about 5 stumps maybe 2 feet in height dont know the diameter but about 18 inches by 15 inches i have alot of oittle cracks like in the pictures i want to cut them straight down the middle and made rustic cuting bords but will there be little cracks even inside the wood that is not exposed at the moment ?

    • wunderwoods says :

      The cracks always start at the outside, so the middle may not be cracked (yet). They will most likely crack like the ends. Hopefully, you will get lots of small cracks instead of one big one that completely breaks.

  6. Kage says :

    My mom received some cookie trivets that are about an inch thick and they split just like in your picture. I did a burning pen technique to create an art piece on one, but I’m now concerned. The crack runs almost to the middle. Will it continue spreading until the piece breaks, or should it stop on its own? I don’t want someone buying it and then it breaking. I didn’t want to put anything on it for fear of making it worse. Thanks for all the info- the post is great!

    • wunderwoods says :

      The crack will stop at the middle. If another one meets it at the middle it will break in two, but one big crack usually relieves the stress so the other cracks aren’t as bad. Keep it inside drying and keep an eye on the cracks. They will get worse as it dries. I wouldn’t try and sell it until it is dry and the cracks stop opening up.

  7. Caleb Chapman says :

    I just picked up a maple log roughly 8′ x 2′ diameter that had been stored inside for 6-7 years. It is very split, most of the burls were cut off in the beginning. I was thinking of forming the top a little for a seat and tables( leave it whole kinda of has that form already) I would leave it outside put it on a stand of sorts to keep it off the ground. I want to know how to seal it large holes and all! Live on the sunny Olympic Peninsula of Wash. St where it only rains 3/4 of the year. Would like to preserve it best I can for the years to come. Can send you a picture of it if that helps. Thank You!

    • wunderwoods says :

      My favorite outdoor sealer is Sikkens Proluxe Cetol Door and Window. It’s your best chance for complete outdoor protection. You will still have to maintain it every other year, but it is the longest lasting outdoor finish I know of.

  8. tratejr says :

    Thank you for a great read! I have two 6″ thick, 36-40″ diameter cookies from an ash tree that was cut down today. I would like to build a table from one of them. I was thinking of putting a thin saw cut from the edge to the center of one to have a controlled crack that I can fill in later. On the other I am debating whether or not to let it soak in PEG or just take my chances with a crack. Is PEG going to significantly increase my chances of having a solid cookie? Also, I don’t know anything about wood. Are my ash cookies likely to fare any better or significantly worse than the woods you have shown in your post?

    • wunderwoods says :

      Any soaking you do will help, but is still no guarantee. At 6″ thick you will need to soak for a long time, in the months, not days or weeks. I haven’t tried to dry ash cookies, so I have no first hand knowledge of how much they will split. I can tell you that ash splits very easily, so any stress will definitely lead to a crack. My guess is that you will have splits, no matter how you treat it.

  9. Chris says :

    This is a great help to those of us amateurs who love working wood. I have a redwood round cut from a stump about 5′ in diameter and about 10″ thick. I was hoping to pond float it for a year or so to prevent the drying damage. I have heard that the pond float will eventually ‘dry’ the wood, even though the saturation from the pond will keep it soaked. Have you ever seen this? Do you think that I would be stuck with the same problem after a year or so with drying damage, or would the water coming from the wood after the year long bath be a different makeup than the normal water content from the live cells? Thank you for your advice!

    • wunderwoods says :

      I have never heard of that approach and my gut tells me that it won’t help much in a short amount of time. I suppose that with a long period of floating that something may physically chance in the wood, but it will take a while. I know that river recovered walnut dries quicker than newly cut walnut.

  10. Maricela says :

    Thank you for your information. My questions are regarding Mesquite. I plan on cutting some 4 inch high rounds for an event in January. How soon should I start cutting and treating the pieces?

    • wunderwoods says :

      If you cut them a couple weeks out from the event, you can get the surface to dry enough so that it won’t get moldy, but not so dry that it will have catastrophic cracks. It will still crack some, but you should be able to avoid the major ones.

  11. Lukasz says :

    Hi Scott. Great article! Very informative and has shed more light on the issues I have had with rounds. I actually found your article while researching Pentacryl. I am currently bidding on a job to make 20 stump stools for a classroom from recently felled red oak trees. The stools will range from 8″ to 16″ in height and diameters will range from about 14-20″. I will debark the logs and was hoping I could apply the Pentacryl all over each surface and deliver the stools in a couple of weeks. Can you provide some feedback on this approach, please? I’m not too considered about a few hairline cracks, but the last thing I want is for these stools to split and warp. This wood is very green and I’m concerned all of my effort may be a waste of time.

    • wunderwoods says :

      Pentacryl will definitely help, but it isn’t foolproof. Even if treated with Pentacryl the wood can still split. The longer you soak the wood the better the odds of it not splitting, so your short timeline doesn’t bode well for you. The bottom line is that it wants to split. Good Luck.

  12. AD says :

    I ran across your post when trying to search for a solution to a slightly different problem. We had several large stands of big-leaf maples removed to stop them from dropping any more large branches on/around the house, and have been left with a few large rounds. (Most of the rounds were hauled away by an acquaintance for firewood.) I had the idea of keeping one of the large pieces (~3 feet across, maybe 1 foot thick) and using it (on edge) as an address marker near the road. I was trying to figure out what to do (or have done) to it to keep it from disintegrating outside. I hadn’t thought of splitting as a potential issue, though.

    I have several choices of large rounds remaining, including one that already has a hole in the center (maybe 4″ x 4″). Any suggestions for me, or is this a terrible idea I should abandon entirely?

    • wunderwoods says :

      It is not the worst idea you have ever had. First off, the piece with a hole in the center has the most potential to not split. With that said, it is possible for a totally solid piece of maple to develop lots of small cracks and not develop one large crack. I would cut more than one slice, let them dry for a few months and see what happens. If they stay together, go ahead and use them. If you keep the wood off of the ground and standing up it will last pretty long since the water won’t pool anywhere. You can seal the wood if you want, but I think it will last a pretty long time unsealed, as long as it can dry out between rain events.

  13. William says :

    Excellent article, and very informative replies to all the questions. Thanks!!

  14. Ed dufort says :

    Great read and great info …thx

  15. Tracy says :

    This is the best article I’ve found yet concerning these problems! I got a large round of pine that’s about 30″ diameter and 3″ thick and being a completely amateur I left it to dry and split. I want to salvage it for a tabletop still, perhaps by placing another wood into the crack or doing the thing mentioned above of cutting it into pie slices and reassembling them. The split is already a couple inches apart and has started to separate the rings towards the middle (the pith is off-center). Do you have any recommendations for how to repair the round or can you direct me to any online tutorials? It may be a lost cause, but I wanted to give it one last shot.

    • wunderwoods says :

      All of the fixes you mentioned are viable options, but will still be obvious as repairs. I am afraid that I don’t know of any tutorials. This is going to be a trial and error type of operation for you at this point. Sorry that I can’t be of more help.

    • Brian says :

      Tracy, you could always use epoxy on it just google epoxy table tops to see what im talking about. its not easy work but i do that for all my wood cookie cuts. i think the cracks in the wood add art that cant be done by my own hands. i also soak my cuts i dont want cracks in polyurethane and i mean like in a bath tub soak. for two weeks on the really big cuts. it works for me but i only do hard woods too so im not sure how it would be on a soft wood like pine but your could always try.

  16. Jeff Oppenheimer says :

    Hello all…. great blog! I just had a large maple cut down and I was talking to the tree surgeon and he said he has a friend who soaks in Pentacryl then buries it for 6 months…. he said it works well…can’t hurt to try right?

    • wunderwoods says :

      I know what the Pentacryl does. Don’t know what the burying does. I imagine the Pentacryl is doing all the work in that case to stop the splitting, while the burying probably encourages spalting.

  17. Jr. Jean says :

    I Have a beautiful slab of mesquite wood that has a large void that runs to the edge of the bark. I would love to turn this into a bar top using a clear epoxy. My question is there anything i can use to keep the epoxy from pouring out like some kind of putty and then be able to remove it from the bark ?

    • wunderwoods says :

      We usually form epoxy dams with wide packing tape, sometimes backed up with a solid backer to keep it flat. To keep it from coming out the bark side, you may need to flip the wood on edge to make the bark the top side for filling.

  18. Patricia F says :

    So I have a question regarding cutting and then using a cookie from a stump to make a wall hanging. We saved some tree rounds (large logs) from a tree that fell into our yard during Hurricane Matthew. We’d like to cut a round from it, have a talented friend paint and letter “I survived Hurricane Matthew” for a decoration and hang it up. If we cut it at an angle, you are saying we’ll have a better change of it not splitting? The first cookie we tried split pretty much right away so we stopped! The wood has been sitting in our garage for 6 months waiting as we just didn’t know what to do at this point! Thanks for any suggestions.

    • wunderwoods says :

      So, splitting should be expected. Slicing at an angle will help a lot, but the angle needs to be pretty steep, like 45 degrees. Since your piece has already had some drying time, this may not make a difference. I would try both a cut straight across the log and one at an angle and see what happens.

  19. Charlie B says :

    I have a very large red oak tree that has to be removed. (15 1/2 feet circumference) that I wanted to cookie saw a table top from. Reading your article, how large of a center hole would you suggest I cut, followed by all other treatments?

    • wunderwoods says :

      I can tell you that a hole in the center will help, but I am not sure what the minimum size is that will do the trick. I think to be safe that the log needs to be more hollow than just having a hole. Pentacryl is the only other additional treatment that will give you a fighting change. Note that it is expensive and does take awhile, but it can be effective.

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