Wood Bowl Crack Fix Secrets

Wood Bowl Crack Fix Secrets – Woodturning Repairing Cracks

It’s hard to think of anything other than a wood bowl crack as a wood bowl turner’s number one enemy. A wood bowl crack appearance can make grown men cry and draw attention away from an otherwise perfectly turned wood bowl.

To prevent and repair cracks in wood turned bowls, we need to understand better what is causing the cracks to form.

Put simply, change is what causes cracks.

More specifically, uneven change causes a wood bowl to crack. Anytime temperature, humidity, or internal moisture content changes, there’s a good chance there are internal structural changes that will take place inside the wood cells, fibers and grain.

It’s imperative as wood turners that we pay attention to these conditions and show our respect as much as possible. When we don’t, our beautiful bowls suffer the consequences.

Wood Bowl Crack Prevention

As they say, “An ounce of prevention keeps bowl cracks to a minimum,” or something like that. So what are we trying to prevent? Uneven, abrupt or excessive wood movement essentially is what we’re trying to prevent.

Wood movement occurs from a few major factors: internal stress, moisture content and temperature changes.

Let’s dive right in and start by covering ways to reduce all of these factors and greatly reduce the chance cracks will visit our bowls.

Length Matters

The length of green wood logs prepared for bowl blanks does make a difference. Even with the additional preventive measures, we will discuss below, there will be some checks and cracks on the ends of the rough-cut bowl blanks. Cutting logs longer than needed will provide excess waste material on the ends of the log that can be trimmed away later.

The length to add to a log will depend on the overall diameter of the log. In general, it’s good to add at least six inches to the log diameter to determine the cutting length.

For example, if a log is 10 inches in diameter, cut the lengths 16 inches long. The extra length leaves about three inches of wood that can crack and check on both ends.

When the time comes to turn the log, simply saw off an inch or so from one end. Look at the newly exposed cut area. Are there still cracks? If so, trim off another inch and check, again. Once no cracks appear, do the same trimming on the other end of the log. Now you have a crack-free log to begin turning.

Half the Trouble

When preparing green wood bowl blanks, it’s critical to get the full round logs split in half as soon as possible. This one step removes a great deal of tangential pressure caused by the inner growth rings and the fact that they are unevenly sized.

The inner rings at the pith of a log are under much more pressure than the outer rings. As the whole round log ages, the outer diameter of the log loses moisture faster than the interior, thereby causing increased tension.

How Cracks Form Wood Logs Bowl Blank Prevention

Watch the Pith

Some people swear the pith CANNOT be in the bowl or the whole thing will blow apart. While this can be true, it’s also possible to leave the pith on the bowl walls, and everything turns out fine.

The particular wood species and how the bowl is created and dried later will greatly determine if the pith will or won’t crack and deform.

At a minimum, the pith will usually stretch and pull away from the turned shape of the bowl as it dries, making the bowl more elliptical than round.

If the pith is something with which you’d rather not take a chance, by all means, avoid it. Cut away any wood that is within the inner circle surrounding the pith. This distance may only be a quarter inch on a small log or several inches around the pith on a larger log.

Either way, I would encourage you to experiment with the pith being left in a bowl or two and try this with different types of wood just to see what happens. You might be surprised.

Wood Bowl Pith Area Movement Intact

Loose Ends

When a log has been cut to the proper length and split in half, that’s a great way to store green logs for a longer period. But before they get tucked away, it’s best to seal the end grain.

Think of the log as a straight linear bundle of long drinking straws. The ends of the straws correspond to the end grain of the log. The fibers run lengthwise through the log much like the drinking straws. And like those straws, the wood’s end grain has small openings allowing moisture to move in and out quickly and easily.

Because of this physical property, the ends of the log will lose moisture content much faster than any other part of the log. The best way to counter this is to seal the end grains with Anchorseal (check current price on Amazon).

Take an inexpensive chip brush (Amazon link) and slather a liberal coating of Anchorseal on each end, covering all the end grain. I also will put a small path along the flat cut edge near the ends to make sure all the end grains are sealed.

Storage

Wood storage plays a big factor in how it will later behave. If you’ve been following along, you understand we want “no sudden movements,” literally. So the storage area you select should continue along these lines.

Green wood storage is a tricky area, because what works for me might not work for you based on your local temperature, humidity, and climate.

So instead of giving some blanket answer, let’s think about what is needed. If the wood is green, wet or has any moisture, it needs to lose that moisture slowly. Or rather IT IS going to lose that moisture. It’s our job to slow that process and make it as gradual and even as possible.

In general, cool, not overly dry, dark (or at a minimum no direct sunlight) spaces will slow this drying process. While I can stack wood along a wall in a very open barn outside where I live in a humid area, that practice will create splintered bowl blanks in the harsh dryness along the Rockies. There, it might be necessary to have a humidified space to store wood, such as a cool basement.

Remember the basics: no direct sunlight, no harsh temperature or humidity changes and avoid excessive air movement. Simple enough, right? Ha!

Wood Bowl Crack Forming Natural Elements Enemies
Wood Bowl Crack Forming Natural Elements Enemies

Get It Done Quicker

Once a bowl blank is mounted to the lathe, it’s a good idea to complete the piece, exterior and interior, as soon as possible. I’ve seen people spend weeks working on the same piece, only to have massive cracks appear midway through the turning.

Why does this happen? The newly turned areas exposed to the elements change unevenly. Usually, the outside of the bowl is fine at first, but the added forces within the bowl’s still solid moist interior are under their original pressure and continue pushing and pulling. The newly exposed area is losing moisture content much quicker than the solid interior, and those internal forces usually manifest as cracks on the outside of the bowl.

It’s important to turn the wood bowl within a reasonable timeframe to prevent these internal forces from ruining a bowl. The bowl needs to be completed more quickly when there is more water content in the bowl blank. A tremendous amount of the wood’s internal pressures are removed when the interior of the bowl is turned away and removed.

If a bowl cannot be completed promptly, inside and out, consider wrapping it in plastic and possibly spritzing it with water first to slow the drying of the outside bowl walls.

Nice and Even

Unevenly turned bowl walls are another contributing factor for the production of bowl cracks. When an area of a wood turned bowl is thick in one area and thinner in another, the two areas dry and move differently. When those movements oppose one another, cracks can form.

Try to turn the bowl to a uniform wall thickness throughout. The base also needs to be turned to a similar thickness as the walls. A thick solid base under a thin-walled bowl will dry much slower than the side walls, usually causing issues.

Wood Bowl Crack Oak Base Too Thick

Avoid the Heat

Once a bowl has been evenly turned, it’s time to sand. Be aware that sanding at too high of a speed can cause heat buildup. If either the lathe or a power sander, or both, are turning too quickly, they will produce excess friction and heat. Moisture is lost more quickly when the wood bowl surface is heated, which can cause cracks to form.

Heat-related cracking is especially true with thin-walled forms and bowls. Slow down the lathe and the power sander and only work for short times in a given area to reduce heat buildup.

An even better approach, although one that makes many people cringe, is to hand sand the final turned wooden bowl.

Bag Green

Once a bowl, which is made with green or moist wood, is complete and off the lathe, the drying process needs to be controlled. Again, the control that is needed is usually to slow the drying process. A great way to slow the drying time is to bag the finished wood bowl.

Before you sweep the floor, grab several handfuls of those moist shavings from the bowl that was just made. Place a shallow bed of shavings in a brown paper grocery bag, then add the new bowl. Fill around and inside the bowl also with those shavings and loosely close the bag.

Store the bagged bowl away in a cool dark place that’s not too dry or moist. Usually, a space indoors at similar conditions to where the final bowl may be displayed is ideal. After all, the wood needs to acclimate to the space where it will eventually live.

Wood Bowl Crack Paper Bag Slow Drying Prevention

There it is! A fine wood bowl crack line appears along the edge of your beautiful bowl. What to do? Even with taking all the preventative measures covered, cracks can occur. If a wood bowl crack appears, don’t fear. There are several options for recovery available.

Fissure Filling

Small bowl cracks can easily be repaired and mitigated. This process is simple and will also help to reduce telltale stains around the crack.

To complete this task, you’ll need a good quality CA super thin glue, CA accelerator and a Clear Spray Lacquer (Amazon links check current prices). Don’t worry, the spray lacquer is only acting as a mask and will be sanded off later when the bowl is completed.

Lacquer is a film finish that sits on top of the wood and once sanded off; it will not limit any final finishes you choose to use. The purpose of first using lacquer is to prevent the CA from staining the wood immediately around the wood bowl crack.

This process is best done while the bowl is still on the lathe before final sanding and finishing. Here are the steps to correctly fill a small to medium wood bowl crack and prevent them from growing.

  1. Spray around the wood bowl crack with lacquer, then let dry a few minutes.
  2. Pack very fine sawdust into the crack.
  3. Using the fine tip provided, drip super thin CA into the crack.
  4. Rub fine sawdust over crack.
  5. Spray crack area with CA accelerator.
  6. Continue turning or finish sanding area smooth.
Wood Bowl Crack Repair CA Lacquer Steps

Decorating

Celebrate the crack! It’s natural, after all, and nothing is perfect. Some cracks look amazing and can be left “as is,” adding unique character to a gorgeous wood turned bowl.

If you’d like to fill, instead of look through a crack, there are many decorative and colorful powders available to highlight the wood bowl crack area. There are even turquoise chips and metal powders that can be used for this step.

If the crack is small, the same steps can be used from above, substituting the colored filler for the sawdust.

Larger areas may require an epoxy mix to fill the entire area. A dam on one side of the bowl can be made by applying tape to cover the cracked area.

Mix the Two-Part, Five-Minute Epoxy (check Amazon for current price) according to the product instructions in a portion large enough for the given wood bowl crack area. While mixing the epoxy parts, add the color mix and then apply the mixture to the cavity.

Let the colored epoxy dry according to the epoxy manufacturer’s details. Again, this step is best done before the bowl is complete, so the repaired area can be further turned and sanded to the desired finish.

If the repair area is large or if you’re interested in creating new material to turn, try the Alumilite Casting Epoxy (check Amazon for current pricing). Alumilite can also be colorized and then sanded after it has dried.

Hickory Bowl Crack Filled With Turquoise Epoxy
Hickory Bowl Crack Filled With Turquoise Epoxy

Architectural Reinforcement

Let’s face it, some cracks become way bigger than originally thought acceptable. But before you turn that bowl into a piece of fancy luxury firewood, consider reinforcing architecture.

Depending upon the bowl and your taste, many things can be done that both transform a “crack” into a “design decision” and make the piece more structurally sound at the same time. Not only can these structures be practical, but they can also be quite creative.

Stitch up a seam by drilling holes parallel to each other on opposite sides of the crack. Using string, leather or wire, stitch the crack up. It doesn’t need to be drawn tight or closed to have a supporting and striking visual effect.

Butterfly joints can be applied as well. Often used in furniture construction, butterfly, or bow tie, joints can be hand chiseled and inlaid into the bowl across the crack area. The dovetail shape of this inlay will hold the crack as is and not allow it to continue to grow, all the while appearing somewhat planned and deliberate.

Wood Bowl Crack Fix Secrets

There you have it, 12 tricks for preventing and repairing cracks. When making wood turned bowls, we need to remember we’re working with a beautiful natural resource: wood. It is not, nor was it ever intended to be, perfect. That is nature.

We can do as much as possible to avoid a wood bowl crack, and deal with them when they do appear, but after all is said and done, cracks happen. I guess it’s all in how we look at them that makes the difference.

How do you deal with wood bowl cracks? Leave me a comment below.

– For details of equipment mentioned in this article see my Recommended Equipment Guide.


Dealing with wood bowl cracks? Reads these articles also:
SUPER FAST WOODEN BOWL CRACK FIX – WOOD GLUE
DRYING GREEN WOOD BOWLS – 6 METHODS FOR SUCCESS
WOOD BOWL REPAIR HOW TO FIX DAMAGE


Happy Turning,
Kent

Comments

  1. Hi, great article and I always appreciate you graphic designer background in you posts :).
    Just wanted to mention that while I don’t know what exactly is in CA glue accelerator, water works great too. Just use up the accelerator and fill the bottle with water.
    It’s been a while since I tried this trick, so if I’m forgetting some inequality, please let me know.
    Thanks for producing such a great resource.

    1. Author

      Hello Raif,

      Thanks for sharing this tip.

      I will try it out.

      I hope the glue companies haven’t been selling us water in a spray bottle as an accelerator all this time. LOL

      But, if it works. Shrug. 😉

      Thank you!

      Happy Turning,
      Kent

  2. I have wood I have let dry for three yrs. black walnut anything i should do or just turn
    Duane Stiles

    1. Author

      Hello Duane,

      I would say, just turn a piece or two and see how it performs. You may still find a bit of moisture inside, but the wood should be pretty stable at this point. Hopefully, it has not dried too much cracked inside.

      Experimentation is the best way to learn.

      Happy Turning,
      Kent

  3. Hi Kent – This is the first article of yours I’ve read and I can guarantee it will not be the last! It is very well written, not only for the beginner, but the advanced woodturner. I am the President of the Ozark Woodturners Club that serves Northern and Central Arkansas and we have a membership of just over 60 members. It is my intention, with your blessing, to offer this article to the membership either in our newsletter or as a demonstration at one of our meetings. Thank you for the time and effort it takes to write this article (and others), I know it is quite an undertaking and much appreciated!

    1. Author

      Hello Darcie,

      Thank you for writing and for your kind words.

      Yes, you may use the information found here for your club newsletter and demo. Please follow the usage guidelines found here > https://turnawoodbowl.com/artwork-usage/

      Please include me on your email list.

      Happy Turning,
      Kent

  4. Your article is very informative but alas, I’m no wood worker. I have an 18″ tall segmented wood vase and a maple big leaf bowl that were both damaged in shipment. Both are unique enough that I’d like to have them repaired. Can you advise appropriate vendors, or how/where to find them?

    1. Author

      Craig,

      I can only recommend finding a local woodworker or maybe someone skilled at a cabinet shop/ I hope that helps.

  5. I’ve been turning bowls for 60 years, and I still learn something every time I read one of your posts. They are beyond excellent. I finally got past the idea that every bowl has to be perfect thanks to you.

    Thank you for sharing your skill.

    1. Author

      Charlie,

      I don’t know what to say except that is one heck of a compliment! Thank you!!!

      Happy Turning and Enjoy,
      Kent

  6. I am plagued with hair line cracks is some of my woods, especially Walnut. I have just read your article on Fissure Filling and plan to try it tomorrow. I have tried the CA thin, but end up with stains. When I sand the stains out, I am back to the cracks. The Clear Lacquer Spray makes sense, if it works. But I am will to try it. This wood is too beautiful to give up on.

    I do not turn my bowls. I use Arbortech tools that allow me to maintain the outer shape of the wood/log.

    1. Author

      Hello Linsay,

      Thank you for your comment and question.

      It sounds like you may need to get the filling element, dust or whatever you are using, farther down into the crack before you apply the CA.

      There is another trick too, which I will be writing about soon. You can apply a small bead of wood glue (I recommend Titebond II) and work it down into the crack, then wipe the surface quickly. Immediately begin sanding across the crack with the grain of the wood, with 120 to 180 grit sandpaper, until the glue skins up and is coated with a fine layer of wood dust. Let the glue dry thoroughly overnight. If the crack areas settle a bit, either sand more or add another layer of the wood glue sanding trick.

      Let me know if that works.

      Thanks,
      Kent

    2. Great article Kent. I have only been turning about 18 months and it is teaching me patience plus I have been meeting some great friends. First article I have read on properly using ca glue. I have also used Milliput with great success after a couple of failures. Keep the articles coming
      Dan frsm Schoharie NY

      1. Author

        Dan,

        Thank you for writing!

        I’m glad you like this technique.

        Please tell us a bit more about how you use Milliput? Do you dry it in the cracks and then sand it? How does it work?

        Happy Turning,
        Kent

  7. Hello Kent, devastated here when I found the amazing bowl I just purchased from my Rasta friend in Jamaica, arrived home with 2 cracks! Housewarming gift for my son & wife! It is cedar, high sheen, one crack is hairline visible to the eye not touch (the old “vintage china check for cracks with eyes closed test). 2nd crack is eye and touch, actually raised a bit, pinhole and it goes from the outer edge then through a knot and continues downward. Guessing that’s not good? Rastas on the beach called me Mrs Jack Sparrow when I set it atop my head, it’s actually quite mid-century modern in shape. From your wonderful article perhaps this beauty had a double whammy of temperature change and baggage handlers!
    Yes, looking for your help please before I try anything. Thanks and Best, Peggy

    1. Author

      Hello Peggy,

      Oh, I can imagine your frustration.

      OK, you may be in luck. From what I’m reading the piece is not separated but just cracked. If this is the case, you can start repairing it by using very thin CA glue, here’s a link. This glue will run right into the finest cracks and bond them together. Hold the piece together with a little pressure and apply the CA. You may want to experiment with this technique on a small area that isn’t as visible, perhaps the bottom area first.

      If the finish is lacquer, it can be repaired by likely sanding the glued crack area and applying new lacquer. Lacquer will soften earlier lacquer layers and bond with them. If the finish is a polyurethane, the wood might need to be sanded down completely before reapplying finish. If the thin CA holds the crack solid and is not visible you may be ok just gluing the piece.

      Let me know if this helps.

      Thanks for commenting and I wish you luck,
      Kent

      PS – and yes, if the baggage handlers weren’t involved it could have occurred due to temperature and moisture content change inside the wood.

  8. I just carved a bowl from cedar ad it was beautiful. I started oiling it with butcher block oil but before I got enough coats on it the bowl cracked on one side from the rim to almost the middle of the bowl. Would I be able to soak it to close the crack? I saw the post above about the grandmother’s bowl but would it hurt a newly carved bowl?

    1. Author

      You can try soaking the bowl. Unfortunately, there are too many variables for me to guess what will or won’t work. Also soaking the wood with oil will also help to revive the wood. Either way, the crack will remain. You might want to try to glue the gap before applying oil. Use a good quality wood glue. Press it down into the crack thoroughly and then sand the crack with sandpaper before the glue dries. The sanding will smooth the gap and fill the glue with color matching dust.

  9. I have an old wooden bowl that my grandmother used to make biscuits. It was passed around. I finally got it about a yr ago. It has a large crack about halfway through the length of the bowl. I would like to repair it to use for decoration. I have heard of soaking the wood/bowl to make the wood more flexible. Can you give me some guidance? Thanks in advance.

    1. Author

      Rebecca,

      Thank you for sharing the story of your grandmother’s wood bowl. I must say, I have not restored an old bowl, but I can share some ideas. I think soaking in water might be too extreme. The wood is probably dried out, but water might be more harmful than good. Consider using a good quality Danish Oil (I have one listed in the Recommended Finishes section) and simply wipe it on the wood generously. If the wood is truly dry it should soak up each coat at first. Allow several hours and or days for each coat to be completely absorbed. Once the wood stays saturated on the surface, the wood fibers have then been filled with the Danish Oil. This will rejuvenate the wood cells and appearance.

      Especially if the bowl is for decoration, consider cutting butterfly inserts. These are small bowtie-shaped pieces of wood that are placed across the crack and inlaid into the bowl. They are both functional and decorative.

      Let me know if these ideas help and I’d love to see the bowl before and after. Thanks again and good luck restoring your heirloom bowl.

  10. The lacquer idea works but so does shellac. I make a solution of shellac diluted 1 to 10using denatured alcohol and keep it in a spray bottle. Before using the CA glue, I spray the piece with the diluted shellac. I spray it generously often covering the whole piece because the glue tends to drip and can drip anywhere. If the glue gets on an area that has not been sprayed, it will stain the wood. I learned this technique from Steven Hatcher when doing inlay work.

  11. I like the suggestion of spray lacquer before applying the CA. Does that not also coat the inside of the crack, which would inhibit the adhesion of the CA when you drizzle it into the crack with the sawdust?

    1. Author

      Great question! I’ve had no trouble with the filled crack not adhering. When spraying I simply make a quick pass across the surface. I’m guessing very little or no lacquer makes it in the crack.

  12. Hi everyone years ago I helped a guy whi was foreman at Fechters in Knysna tgey made the most beautiful wooden furniture uncle Laurie always had a cloth which he dipped in parraffin and everytime he turned a bit he will just hold the cloth lightly to run over the piece you have done it never cracks this way. I bought a small Unimat set from Germany I want to start making dolls house furniture. Hold thumbs because I have to teach myself. Blessings Anette von Mollendorff

  13. Merci pour ce documentaire , qui va etre un outil de travail ,moi qui commence dans le tournage sur bois et qui veut faire des bols

    1. Author

      You’re welcome! Yes, the lacquer does a good job reducing the CA stains. It will depend a bit on the type of wood and dryness, but in general, I’ve found it works well. Happy turning!

  14. this is really appreciated information, I love it and thank you very much for this. I only started this hobby in late December 2017 and have already created around a dozen bowls segmented and natural among other things. I am loving my new hobby and have set up my 8 foot by 6 foot workshop with, (I think), all the tools I need to do justice to the things I make. Getting back to the subject of cracks I have ha one or two bowls that have had cracks appear and have used ca glue and sawdust to fix them but not always to my satisfaction, after reading your fixes I’m sure things will only get better. Thank you very much indeed.

    1. Author

      Thanks Ron! Glad to hear you’re enjoying wood bowl turning. I hope this article provides some useful information as you continue.

Leave a Comment