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Crack!

H

herb

Joined
Mar 4, 2007
Messages
56
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8
Location
Lakewood, Colorado
Hi,

I gave a fiend a salad bowl that I had turned. She was in the process of using if for the first time when it cracked. It was a loud pop and cracked from the rim to the bottom of the bowl. The crack was about 1/3 at the rim.

Some background. The wood is locust that I turned green and dried the blank (end grain sealed in paper bags) for 11 months. The bowl is 13" and rather shallow at 2.5 inches in calabash style. The bowl is about 1/3 inches thick.

Any ideas here?

Herb
 
things happen, probably could tell more if you had 5 bowls and they all cracked, one bowl is not enough of a sample
 
herb said:
Hi,

I gave a fiend a salad bowl that I had turned. She was in the process of using if for the first time when it cracked. It was a loud pop and cracked from the rim to the bottom of the bowl. The crack was about 1/3 at the rim.

Some background. The wood is locust that I turned green and dried the blank (end grain sealed in paper bags) for 11 months. The bowl is 13" and rather shallow at 2.5 inches in calabash style. The bowl is about 1/3 inches thick.

Any ideas here?

Herb
Click to expand...

Hello........

Given the information provided, it's doubtful that any conclusive thought can be given. However, a few questions would provide additional information that might provide stimulus for speculation......

Did the crack occur with the grain, or across the grain?

When you say the crack is "about 1/3 at the rim", do you mean to say it originated at the rim and ended at about 1/3 the distance of the total height?

Was there any force applied, such as a drop or bump associated with the loud pop?......or?

Could it be that the dried wood was now under the influence of salad oils, water, or other sudden application that could influence the moisture content? If the grain was properly sealed, this is unlikely to be a cause.

Does your definition of "calabash" mean an inward slanting rim?

Judging from your comment, I suspect you think the crack may have been present during the seasoning process. If so, is there anything that makes you suspect this is so? If it was, it's always a possibility this is a source of the crack. I have had hairline cracks in seasoning bowls.......cracks that I could not, or did not detect until sometime after mounting for final turning.

...................................



Personally, I have not experienced a suddenly appearing crack that didn't originate without some sort of applied force........but, this is not to say that it's not a possibility. Maybe someone else can confirm.......?

I did have a bowl crack suddenly when mounted in the expand mode on my mega jumbo jaws......by simply turning on the power and the rpm preset to something well above zero rpm. Since then, I always turn the potentiometer to zero every time I start up, and gradually increase the rpm......no problems since that rule has been in force. In this example, there definitely was some "applied force" to induce the crack.

Also, I had a crack occur on a laminated bowl years later.....this was with the lamination, and across the grain in one section. I attribute this as due to uneven warping of different woods.

Also had a Wenge bowl crack years later.....with the grain. Nobody ever heard a "pop" with that one, but it could have happened suddenly, I suppose.

There was no outside influence to either of the latter two examples. (Wenge, laminated)

Awaiting further input.......

ooc
 
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Sounds as if the wood might have been affected by a change in temperature or humidity. Wood continues to move and it sounds as if there was a flucuation that caused the crack.
 
A few other thoughts are --

  • Was the rim close to the pith?
  • Did the owner put it in the dishwasher?
  • Did they stick it in the microwave?
Like Odie, I also do not understand what your statement about the crack being 1/3 at the rim means.

It might be useful if you posted a picture of what the bowl looks like now.
 
I just noticed your statement that it was an end grain turning. A very shallow bowl with such a large diameter and turned end grain is just begging for trouble especially if it was turned so that the pith is near the center. Having said that, something more than simply putting a bit of salad in the bowl had to be going on -- perhaps soaking up lot of moisture from something.
 
Years back I wanted to pour a patio (decks were still in the future) for our house in California. I consulted literature and contractors and found that there were some things which would guarantee cracks, but there were no things that would prevent them 100%. Some slabs or bowls crack, some don't. If the rim curves in (I think the endgrain was merely sealed, right?) it is weak times two for being endgrain and curving in. Grab it with your thumb in the right place and it might experience enough stress to force a crack. Start one and it will run.
 
herb said:
Hi,

I gave a fiend a salad bowl that I had turned. She was in the process of using if for the first time when it cracked. . . . The bowl is 13". . . .
Herb
Click to expand...

You gave a bowl to a woman who is a fiend? That could explain it right there. Also, the bowl is thirteen inches. That's an unlucky number and 1/3 is 13. Try making the next bowl twelve or fourteen inches and 1/4" or 1/2" thick.

Without a picture, it's hard to guess why it cracked, but having the rim too close to the pith is a common cause of cracking. If the bowl sat on the lathe in dry Denver between turning sessions, the end grain could dry out. If you can't turn the bowl quickly in one session, put it in a plastic bag between turning sessions to equalize the moisture content.
 
Crack

The only crack of that nature I have had was here in dry Denver last summer. I was staining a turned and sanded pine calabash bowl from the day before. The wood was seasoned but the moisture content I don't know, also it was not end grain. THe bowl was sitting outside in the sun for awhile-I got some cold tap water, stirred in some stain powder and started in. Before staining was complete there was a fairly loud CRACK and a crack opened up runnning from the rim about 1/3 of the way down the bowl. The cause I am sure was putting cold water on a warm bowl but I have done that before many times. As they say the law of averages catches up with you.
 
One of my customers had that happen recently with some Mountain Mahogany bowls I made for him. He put some hot food into them, which I have never had a problem with before on other woods. Possibly, since Mountain Mahogany is a high desert wood (8500 ft out side Las Vegas), it doesn't do well with big changes in moisture levels. Then I got Mike Mahoney's new vides about Making Heirlooms. He said that the softer hard woods are better at taking the stresses of every day use while the harder ones like Osage and Locust were not as good. I am still pondering that one, but it does seem to make some sense.

As to the calabash style of bowl, I never did like them. I just can't get over the rim slanting inwards. How do you get the last bit of stuff out of the bowl except by turning the bowl up side down?????

Concrete: the only two guarantees that you can give with concrete is one it will crack, and two, no body is going to steal it.

robo hippy
 
As a fellow who has made many hundreds of calabash bowls straight up the log in many different woods I am going to be on the side of those who say luck of the draw so to speak. But now that its cracked consider a traditional repair such as a butterfly patch. Dont try to mash the wood back together. Fill the crack with sanding dust and ca glue. Or try Jerry Kermodes stitch patches. In ancient Hawaii it took so long to make a bowl that it was worth the time to repair. They add value to a work. We all know that popping sound. We all very much dislike it. I unloaded a hot kiln full of dry bowls one time into a wheelbarrow and headed to the shop. Within about four minutes I had five or six bowls make that horrible sound. From then on I let the load cool down.
 
crack

Hi,

Thanks for your responses. Here is some more info and pictures. As far as I know there was not a bump or drop. She was using it for first time and eating from it when POP - quite loud. so it was not a crack that expanded. It is not an end grain turning nor close to the pith. I turned a large platter from the same log that was closer to the pith. From the picture it looks to me like the crack is 1/3" wide at the rim. I've heard from one other person about locust cracking like this. Pictures represent before and after
 

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herb said:
Hi,

Thanks for your responses. Here is some more info and pictures. As far as I know there was not a bump or drop. She was using it for first time and eating from it when POP - quite loud. so it was not a crack that expanded. It is not an end grain turning nor close to the pith. I turned a large platter from the same log that was closer to the pith. From the picture it looks to me like the crack is 1/3" wide at the rim. I've heard from one other person about locust cracking like this. Pictures represent before and after
Click to expand...

herb........

Wow, now that is a big crack! I can understand the disappointment it was. 🙁

Your bowl may not have had pith in it, but it's across the grain......and pointing to where the pith would be. I think that is significant.

Honey Locust......is that correct? I have not seen this in this particular species.....yet! It is possible there is something about the species that is adding to the equation.........and, it sounds like you've heard from others who believe it is. I just finished a Honey Locust bowl in the last month......so, will hang onto it so I can watch it very closely! 😉

As to the source of the crack........I'd say the pith did influence this one, and you may have had similar results with the other platter, if the same exact shape were involved.....and maybe not! 🙄 (I believe it was John Lucas who mentioned that wood is a fickle thing somewhere else in the forum......true!)

Is the photo with the salad in the bowl, taken just prior to the incident?

There is no repairing that one........

ooc
 
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Bottom is very wide and doesn't appear to have much slope on the outside. That left a lot of drying stress available. Somehow whatever she did to the bowl was the straw that broke it. I'll take your word about there being no heart checks in the log to cue you to any particular weakness. More slope to the sides might have preserved it, but it shouldn't have broken anyway.

Not enough undercut to justify my original guess.
 
crack

Hi,

Again, thanks for replies. Yes Odie, the picture with the salad in it was taken just before the incident. Also, she is a friend not a fiend. Wow, what a difference a letter makes.

I also think that the design of the bowl has something to do with it. As you can see in the crack picture the side opposite of crack is bowed up. I think it held a lot of tension in it. I have one more blank of this wood - we will see.

Herb
 
I mis-read your original statement and thought you meant that it was an end grain turning that was dried in a paper bag.

From the photos it is clear that the wood was not completely dry when it was final turned as evidenced by the warping. That is the typical warping pattern especially if the rim is close to the pith -- the area close to the pith will still be high while the part farthest from the pith will shrink the most and shrink downward in this type of grain orientation. The curvature of the growth rings shows that the rim was not very far from the pith, especially on the far side of the bowl where there is a lot of distortion.
 
That's too bad about your bowl, Herb. Your friend must have been quite startled by the surprise POP. I know I would have been.

I had a similar experience when I applied shellac to a beetle-killed pine bowl. The finish soaked into the end grain so quickly the bowl went POP and developed a hairline crack with a slight misalignment in the same classic location as your bowl.

I have not tried this but some people swear by boiling to ease tension in Pacific Madrone blanks. I think they boil the blanks when they are still green. Maybe boiling would help relieve tension in Locust.
 
I some one showed me that bowl, and asked me why it cracked, I would say, "Oh, you tried to dry it too fast." That big of a crack is a sure sigh of major stress relief. There appears to be some warping of the bowl, but not much, so it is hard to tell how dry it was. After 11 months in a paper bag, it should have been stable. If some one is taking one of my Oregon bowls to Arizona, I will tell them to put it in a closet, or a paper bag for a few days to let it acclimate or adjust to the change of environment.

As to the Madrone, you have to either turn it thin (1/4 to 3/8 inch max) and slow dry it, or boil it. If you thick turn it, even if you seal it and are able to dry it without it cracking, it will warp so much that the 10% rule won't even be close. I have one bowl I turned before Christmas that came off the lathe at 22 inch diameter. It finished moving at 25 by 17 inches. Boiling is the only way to stabilize it, unless you want to sink it in the rain barrel for a year or so.

robo hippy
 
problem?

You my fiend(friend) have unknowingly created the legendary exploding bowl.

Known to only the oldest of trickery and bafoonery. Such as myself.......:cool2:

Just like an exploding cigar, it is only a success when the user is holding it.

If a cigar explodes in the woods...?

All of the other responses refer to the failure of the piece. No, no, no !

I wish to welcome you on your journey to a larger world.

All further bafoonery questions should be directed my way.

Thanks

DJ
 
WOW! That is pretty dramatic for certain. Honey locust is such a gorgeous wood; its a pity to see your post. I don't have nearly the experience with salad bowls that robo hippy has, but I have worked with a bunch of locust. First off, this may be totally off base; as I've only worked with black locust on the lathe. I milled a bit a few years back, and was very surprised at how much it warped in drying, even though the tree was very straight grained and clear of branches. Lots of tension in there. Similarly, a large honey locust that I slabbed into natural edge boards 3" thick warped a fair amount. Every bowl I've turned from black locust has moved significantly. I don't have measurements, and they wouldn't be useful anyway, as they are natural edge pieces, but enough so that I really have to work a section at a time when hollowing the inside, and doing finish cuts along the way. As the bowl spins out water by centrifugal force, it dries out, and starts to move QUICK! By the end of the turning, the rim is nowhere near round anymore.

I guess I'm not offering any sort of solution to your problem, but merely sharing my experience with the tension and movement of locust in general...
😱 😕 😱
 
FWIW, Honey locust shows 4.2 radial, 6.6 tangential shrink. Volumetric is 10.8 Both the ratio and overall is pretty near normal among hardwoods.

Black shows 4.6, 7.2, and 10.2. Also pretty normal.

Madrone, The Hippy favorite, shows 5.6, 12.4, and 18.1 Pretty wild by comparison.

Cherry, my favorite is 3.7, 7.1, and 11.5, but people constantly call it and other "fruitwoods" unstable in drying.
 
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