Can someone please explain why after a month of natural drying the pieces of Florida hickory I was spindle turning for a vase began cracking approximately three days after completion. Being a novice turner and having success with oak, purple hearth, osage orange, and many other woods, does the heavy grain of hickory have something to do with the cracking and does it require more time to dry? While working the wood it certainly appeared to be quite dry. Thanks for the help.
-
June 2025 Turning Challenge: Turn a Wand! (click here for details) -
Sign up for the 2025 AAW Forum Box Swap by Monday, June 30th (click here for details) -
Congratulations to Walker Westbrook for "Archaeological Record" being selected as Turning of the Week for June 23, 2025 (click here for details) -
Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.
Hickory Cracking
- Thread starter Bob Fox
- Start date
- Joined
- Apr 28, 2004
- Messages
- 117
- Likes
- 1
- Location
- Southwest Missouri
- Website
- www.hiltonhandcraft.com
The simple answer is that it wasn't dry yet. This may be just one part of your problem though. If you mean why did it wait for so long after you completed it, then it's just the fact that the uneven forces in the wood due to drying took that long to develop the cracks. Sometimes it goes quick and sometimes only after a few weeks or months will cracks develop if they're going to.
First, the dry/wet issue:
One month is nothing for air drying for pretty much any wood specie. The general rule is 1 year of air drying for each 1" of thickness. Adjust time up or down depending on the type of wood (see below).
Lots of ways to help shorten the time to dry. See the archives or just do a search on the web. Lots of opinion, conjecture, experimenting and "proof" out there to make any brain soggy.
The only sure way is to let it air dry. Next best is to kiln dry it. Regardless of what method you choose, there are pitfalls with them and it takes time to figure it out depending on your own situation.
One quick (if not very scientific) way to tell if a piece of wood is "dry" is to touch it. If it feels cool in any way (assuming it's at room temperature of course), it's not dry. You CAN get wood too dry but that's not usually a problem you need to worry about at this stage.
Type of wood:
Your Purpleheart is likely already dry by the time you buy it unless you buy direct or have a tree of it growing in your backyard. Same goes for many of the exotics unless it's encased in a waxy substance (like most ebony or snakewood, etc.). Those you should really consider wet as well. Let dry a LONG time if you want to keep them nice.
Red oak (I have no idea what kind you have as there are LOTS of varieties of oaks with vastly different characteristics) is very very difficult to dry in larger thicknesses (over around 2"). Red oak is one of those "standard" woods that kilns and kiln mfgs use to test their equipment and schedules. It cracks and with a vengence (usually lots of cracks in the ends and just a few large ones along the length of a board or spindle blank.
Osage Orange likes to crack but won't generally make huge ones. Lots of little ones. It warps nicely when it's thin too but that's another discussion.
Hickory (and it's kin species) is one of those woods that just likes to crack. American Sycamore doesn't (not that it won't, mind you) crack easily. That's just the way it goes. They're all different and you treat them as such. Much of it has to do with the different movement properties of the wood (shrinkage values on different planes) as it dries but it also has to do with the rate of moisture loss of a given species, etc. Do a search on "Wood Shrinkage Table" and you'll get the idea.
Other factors:
It could have been any number of other factors affecting that particular piece of wood too. Let's assume that that hickory was dry (but at just one month of air drying it's not going to be by a long shot).
Was it downed by the Florida hurricanes? Major problem. Storm trees (be it hurricane, tornado, major floods, or lightning, etc.) are damaged. How damaged isn't always apparent until you start working it. Reputable loggers and harvesters of trees note these problems and can follow along with the grading. There's going to a BUNCH of bad wood on the market (several markets including turning blanks) in the next 3 years because of all of the hurricanes this year. I won't touch most tornado trees for my logging operations. However, I DO take much of it for my own turning blanks. I note on the blank this potential problem and treat it a little differently because of the trauma it went through. It could affect the working characteristics.
Did that tree have common internal stress problems such as ring shake, wind shake, disease, compression, and so on? You aren't likely to know unless you study the tree closely. These things can also cause problems leading to your cracking problem.
How about any bark inclusions, figure (quilting, curl, birdeye, etc.), radical grain changes, embedded limbs, rocks, etc.? All factors to consider in how wood behaves.
And let's not forget the natural tendency for cracks to develop with the pith (center growth area of a tree) left intact in the piece. The areas outside of the pith are shrinking, expanding and moving at different rates due to drying. This causes great stress to develop there and radiate outward. If the pith is off-centered in the log section, then you can add another potential problem on top of that. (Does anyone think Dietrich noticed this inclusion? Hmmmm)
How about natural growth conditions other than environmental? What does that mean!? Was it growing on a steep incline? Very near a building or in a cluster of trees? Or maybe all alone in a field? How about in a place where constant winds are a force acting on the tree? All of these influence (to some degree or another ... which we won't always know about or detect until we work the wood) the stresses in the tree that might come out as you work it. Ever had a perfectly straight, nicely kiln dried piece of lumber go nuts on you as you tablesaw it .... binding on the blade or else twisting all to heck just before you're ready to use it? No, we're not always talking about huge, noticeable stresses or problems coming out as we work them. It can be as simple as a little extra movement/warping as you hollow out that bowl. But these are all things to consider. And, personally, it's one of those little unknowns that makes working wood so much fun. It's not static and it's not always what it looks like. Same goes for people too, but I digress....
Thickness is a key factor. If you were making some miniature vases (and, yes, some of us do), from 1/2" thick wood, then one month *might* be enough to have it dry enough. But I'm assuming you had a thickness of at least 3", right? That takes awhile to dry ... a year (simple air drying) at the very least and more likely 2 years (3 to be safe).
Yet another common problem is taking a "dry" piece of wood from one environmental location to a much drier climate (say Florida to the deserts of Arizona). If it's not handled properly, a piece of wood that's been "dry" for 30 years in one place can severely crack and/or warp if its' climate is altered dramatically and quickly. That's because "dry" is very much relative to the average moisture and heat conditions of the environment it is in. So, what is "dry" in Florida might be a 20% moisture content. What is "dry" in some parts of Arizona is 8%. Big difference there. So, "dry" is a relative term when talking about wood products.
This is why I mentioned above about being able to make wood too dry. Problems can occur when you artificially dry wood to too low of a moisture content (for your given climate conditions) and then begin working it especially. Not exactly the same problems as having it too wet but still problems. Things like warping and swelling can occur and can be quite the challenge to take care of when working a hollowform, for example.
So, lots of things that could have caused the cracking. If I would take a professional guess given no other information, it would be that one month of air drying just wasn't close to enough for that wood.
First, the dry/wet issue:
One month is nothing for air drying for pretty much any wood specie. The general rule is 1 year of air drying for each 1" of thickness. Adjust time up or down depending on the type of wood (see below).
Lots of ways to help shorten the time to dry. See the archives or just do a search on the web. Lots of opinion, conjecture, experimenting and "proof" out there to make any brain soggy.
The only sure way is to let it air dry. Next best is to kiln dry it. Regardless of what method you choose, there are pitfalls with them and it takes time to figure it out depending on your own situation.One quick (if not very scientific) way to tell if a piece of wood is "dry" is to touch it. If it feels cool in any way (assuming it's at room temperature of course), it's not dry. You CAN get wood too dry but that's not usually a problem you need to worry about at this stage.
Type of wood:
Your Purpleheart is likely already dry by the time you buy it unless you buy direct or have a tree of it growing in your backyard. Same goes for many of the exotics unless it's encased in a waxy substance (like most ebony or snakewood, etc.). Those you should really consider wet as well. Let dry a LONG time if you want to keep them nice.
Red oak (I have no idea what kind you have as there are LOTS of varieties of oaks with vastly different characteristics) is very very difficult to dry in larger thicknesses (over around 2"). Red oak is one of those "standard" woods that kilns and kiln mfgs use to test their equipment and schedules. It cracks and with a vengence (usually lots of cracks in the ends and just a few large ones along the length of a board or spindle blank.
Osage Orange likes to crack but won't generally make huge ones. Lots of little ones. It warps nicely when it's thin too but that's another discussion.
Hickory (and it's kin species) is one of those woods that just likes to crack. American Sycamore doesn't (not that it won't, mind you) crack easily. That's just the way it goes. They're all different and you treat them as such. Much of it has to do with the different movement properties of the wood (shrinkage values on different planes) as it dries but it also has to do with the rate of moisture loss of a given species, etc. Do a search on "Wood Shrinkage Table" and you'll get the idea.
Other factors:
It could have been any number of other factors affecting that particular piece of wood too. Let's assume that that hickory was dry (but at just one month of air drying it's not going to be by a long shot).
Was it downed by the Florida hurricanes? Major problem. Storm trees (be it hurricane, tornado, major floods, or lightning, etc.) are damaged. How damaged isn't always apparent until you start working it. Reputable loggers and harvesters of trees note these problems and can follow along with the grading. There's going to a BUNCH of bad wood on the market (several markets including turning blanks) in the next 3 years because of all of the hurricanes this year. I won't touch most tornado trees for my logging operations. However, I DO take much of it for my own turning blanks. I note on the blank this potential problem and treat it a little differently because of the trauma it went through. It could affect the working characteristics.
Did that tree have common internal stress problems such as ring shake, wind shake, disease, compression, and so on? You aren't likely to know unless you study the tree closely. These things can also cause problems leading to your cracking problem.
How about any bark inclusions, figure (quilting, curl, birdeye, etc.), radical grain changes, embedded limbs, rocks, etc.? All factors to consider in how wood behaves.
And let's not forget the natural tendency for cracks to develop with the pith (center growth area of a tree) left intact in the piece. The areas outside of the pith are shrinking, expanding and moving at different rates due to drying. This causes great stress to develop there and radiate outward. If the pith is off-centered in the log section, then you can add another potential problem on top of that. (Does anyone think Dietrich noticed this inclusion? Hmmmm)How about natural growth conditions other than environmental? What does that mean!? Was it growing on a steep incline? Very near a building or in a cluster of trees? Or maybe all alone in a field? How about in a place where constant winds are a force acting on the tree? All of these influence (to some degree or another ... which we won't always know about or detect until we work the wood) the stresses in the tree that might come out as you work it. Ever had a perfectly straight, nicely kiln dried piece of lumber go nuts on you as you tablesaw it .... binding on the blade or else twisting all to heck just before you're ready to use it? No, we're not always talking about huge, noticeable stresses or problems coming out as we work them. It can be as simple as a little extra movement/warping as you hollow out that bowl. But these are all things to consider. And, personally, it's one of those little unknowns that makes working wood so much fun. It's not static and it's not always what it looks like. Same goes for people too, but I digress....
Thickness is a key factor. If you were making some miniature vases (and, yes, some of us do), from 1/2" thick wood, then one month *might* be enough to have it dry enough. But I'm assuming you had a thickness of at least 3", right? That takes awhile to dry ... a year (simple air drying) at the very least and more likely 2 years (3 to be safe).
Yet another common problem is taking a "dry" piece of wood from one environmental location to a much drier climate (say Florida to the deserts of Arizona). If it's not handled properly, a piece of wood that's been "dry" for 30 years in one place can severely crack and/or warp if its' climate is altered dramatically and quickly. That's because "dry" is very much relative to the average moisture and heat conditions of the environment it is in. So, what is "dry" in Florida might be a 20% moisture content. What is "dry" in some parts of Arizona is 8%. Big difference there. So, "dry" is a relative term when talking about wood products.
This is why I mentioned above about being able to make wood too dry. Problems can occur when you artificially dry wood to too low of a moisture content (for your given climate conditions) and then begin working it especially. Not exactly the same problems as having it too wet but still problems. Things like warping and swelling can occur and can be quite the challenge to take care of when working a hollowform, for example.
So, lots of things that could have caused the cracking. If I would take a professional guess given no other information, it would be that one month of air drying just wasn't close to enough for that wood.
Last edited:
- Joined
- Apr 26, 2004
- Messages
- 43
- Likes
- 0
- Location
- lincoln, nebraska
- Website
- woodturners.underthecouch.com
Great info
Andrew, thanks for a lot of very good info. Cut and paste material for my ever-growing 'Things I must know about woodturning' file.
rick
Andrew, thanks for a lot of very good info. Cut and paste material for my ever-growing 'Things I must know about woodturning' file.
rick
Hey guys.
Andrew, you forgot to mention pith. If the pith is still in the wood when you turn it, it acts as a fulcrum point and cracks will radiate towards it. Milling the pith out of the wood will go a long ways to minimizing cracks.
Dietrich
Andrew, you forgot to mention pith. If the pith is still in the wood when you turn it, it acts as a fulcrum point and cracks will radiate towards it. Milling the pith out of the wood will go a long ways to minimizing cracks.
Dietrich
- Joined
- Apr 28, 2004
- Messages
- 117
- Likes
- 1
- Location
- Southwest Missouri
- Website
- www.hiltonhandcraft.com
Dietrich,
Ummmmmm ...... no I didn't. Really. It's there. Take another look.
"Yeah, that's the ticket!"
Ummmmmm ...... no I didn't. Really. It's there. Take another look.
"Yeah, that's the ticket!"
AAAAAHHHH, SSSSOOOOOOO........
Gotcha, Andrew. Tis there.
I usually consider it a problem whether off center or not. Sometimes, even in the most consistant piece of wood, if I leave it in, it's gonna end up pithing me off later.
Dietrich
Gotcha, Andrew. Tis there.
I usually consider it a problem whether off center or not. Sometimes, even in the most consistant piece of wood, if I leave it in, it's gonna end up pithing me off later.
Dietrich
- Joined
- Apr 28, 2004
- Messages
- 117
- Likes
- 1
- Location
- Southwest Missouri
- Website
- www.hiltonhandcraft.com
Bob,
You are most welcome. I'm impatient too so I just deal with the green wood as it is. Much easier to work with being green as long as you know what is (or at least might) happen as you work it. Drying after turning is a major problem and there's been numerous ways to deal with it (do a search here and other places on the web on Bowl Kiln, Boiling, Microwaving, Bagging, LDD, sealing, and as of late at least in the woodturning world - Alcohol). Turn it fairly thin and a consistent thickness (this is a bit more important than thinness) from rim to base to minimize the cracking problems. Still, no guarantees. That's what you get when playing with nature.
Dietrich,
You caught me! I meant to say in the edit of my post that having the pith (or the center part of the tree ... which isn't always in the exact center of the log) in the piece you're turning is likely to cause more chance of cracking. Not necessarily that the pith is centered in the turning or not. Although I do see more problems with cracking when the pith is up near the rim or down at the base rather than centered on a bowl or hollowform.
You're so pithing punny, Dietrich
You are most welcome. I'm impatient too so I just deal with the green wood as it is. Much easier to work with being green as long as you know what is (or at least might) happen as you work it. Drying after turning is a major problem and there's been numerous ways to deal with it (do a search here and other places on the web on Bowl Kiln, Boiling, Microwaving, Bagging, LDD, sealing, and as of late at least in the woodturning world - Alcohol). Turn it fairly thin and a consistent thickness (this is a bit more important than thinness) from rim to base to minimize the cracking problems. Still, no guarantees. That's what you get when playing with nature.
Dietrich,
You caught me!
I meant to say in the edit of my post that having the pith (or the center part of the tree ... which isn't always in the exact center of the log) in the piece you're turning is likely to cause more chance of cracking. Not necessarily that the pith is centered in the turning or not. Although I do see more problems with cracking when the pith is up near the rim or down at the base rather than centered on a bowl or hollowform.You're so pithing punny, Dietrich
Thanks, Andrew.
I'm appreciative of your pithy comments. I hope you'll forgive all my wise cracks. Your first comments really did get to the heartwood of the matter and had more than a grain of truth to them.
Well, enough from me, gotta split.
Dietrich
I'm appreciative of your pithy comments. I hope you'll forgive all my wise cracks. Your first comments really did get to the heartwood of the matter and had more than a grain of truth to them.
Well, enough from me, gotta split.
Dietrich