Self healing "checking" to wood........?

[Odie]

I finished a Padauk shallow platter, the other day.....and, I'm a bit confused about some hidden checking (?) that was not apparent until I turned the bulk of the wood away towards a final shape. What it looks like to me is checking. Could be stress cracks, or wind checks.....whatever you want to call it. What is confusing to me is after the piece was finished completely, I couldn't detect any separation at all. There was a haze on both sides of the checking, and by my best guess, it looks like the check may have healed itself while the tree was still alive.

I don't think I've ever seen this exact thing before, so I'm not sure what I'm looking at......but it certainly does look like checking of some sort, but the check can't be spread open (It's a thin wall platter, so it can be bent by hand)

Is my guess that the tree self healed possible, or is there something else that might explain this?

ooc

 

[john lucas]

Did you have it near a Billy Graham album. 🙂 I've had checks close up but I'm pretty sure they didn't heal. Maybe it just wouldn't flex enough to show the checks.

 

[Bill Boehme]

As far as I am concerned, there isn't any healing going on. I have taken a couple classes with famous turners where we were making hollow forms using wet, but dead wood. In one class the wood was hackberry which tends to dry fairly fast when it is thin and lots of exposed end grain. We kept a spray bottle handy to prevent checking, but occasionally a tiny crack would show up anyway. The remedy was to keep the wood wet, but also by spraying the wood, it would swell enough to close the crack. The part that I disagree with was the statement that the wood would seal back together. My contention is that as the whole piece dries and shrinks a bit, that is the reason that the wetted swollen area around the crack is no longer able to open up. The bottom line in most cases is that the details of what happened don't really matter. If we can't see it then it isn't there. A lacquer or varnish finish probably helps to "glue" these microscopic cracks that have closed up.

 

[hockenbery]

Odie, not sure what you have

Could be heat checks dry wood too much bevel riding. Or too much heat from sanding.
The wood sensitive to heat develops little webs of checks

Could be some checks in the wood from the drying process.
The outside dried too rapidly prevent the interior from drying properly and networks of checks are inside.

Moisture from the air or finish swells the fibers and the holes close up.

Unlikely you have a wind shake. Wind shakes are a separation of the growth rings. I have seen lots of them. Never seen one heal itself.

Have fun

 

[Tim L]

I've had some cracks on the end grain close up before too. I think it was because of the humidity or when I placed it in a plastic bag. The cracks eventually opened back up again for me but since you put finish on it while the cracks were closed you may have had a turn of luck and they will stay closed. Hope for the best.
Tim.

 

[Bill Boehme]

Second Opinion

.... There was a haze on both sides of the checking, and by my best guess, it looks like the check may have healed itself while the tree was still alive...

I had to re-read your post a few times before it dawned on me that maybe you are talking about a characteristic you saw the wood and not something that happened while you were turning the platter. The clue was your statement that the tree may have healed itself while it was still alive. Since it would be a good assumption that you aren't turning live trees, I'll go with my second opinion. I'm not sure how much healing might be possible since only the outer part of the tree is actively growing. Maybe what you saw was some sort of subtle figure or perhaps medullary rays.

 

[Odie]

I had to re-read your post a few times before it dawned on me that maybe you are talking about a characteristic you saw the wood and not something that happened while you were turning the platter. The clue was your statement that the tree may have healed itself while it was still alive. Since it would be a good assumption that you aren't turning live trees, I'll go with my second opinion. I'm not sure how much healing might be possible since only the outer part of the tree is actively growing. Maybe what you saw was some sort of subtle figure or perhaps medullary rays.

Hard to say, Bill..... What I forgot to mention is this piece of Padauk was kiln dried, with less than 10% MC. It was a KD board that was about 3/4" thick. Unfortunately, I can't look at the original board again, but I didn't notice any indication at all before turning it. It is a series of faint darker lines that look like checking, but I can't see, or feel any separation. I noticed it prior to applying natural Danish oil, but it was more noticeable after the application. Yes, if there was anything there before mounting it on the lathe, it's was so faint that I didn't notice anything unusual. At some point while removing the interior, I noticed them, and they were darker than the surrounding wood.....kind of like worm tracks look to it, but in a pattern that looks like checking. I tend to think that whoever ends up with this platter, they are bound to notice it.......but to me, it really sticks out, because I know it's there! 😱 The wood itself seems solid enough......just bugs me! Ha!

ooc

 

[Mark Mandell]

Bill is correct. Once heartwood develops a crack, it cannot heal. Trees can only "heal" exterior damage to the cambium and the bark, and then only by encapsulating (growing around) the scar. It is common for checks and cracks to close up given changes in moisture content. What looks solid in the humid summer may exhibits hairline fractures in dry winter air. You can get a fairly good indication if your piece of wood has fractures by tapping it. If it's sound, dry hardwood will produce a clear tone. With fractures present, it will ring like a potato.

 

[hockenbery]

Hard to say, Bill..... What I forgot to mention is this piece of Padauk was kiln dried, with less than 10% MC. It was a KD board that was about 3/4" thick. Unfortunately, I can't look at the original board again, but I didn't notice any indication at all before turning it. It is a series of faint darker lines that look like checking, but I can't see, or feel any separation. I noticed it prior to applying natural Danish oil, but it was more noticeable after the application. Yes, if there was anything there before mounting it on the lathe, it's was so faint that I didn't notice anything unusual. At some point while removing the interior, I noticed them, and they were darker than the surrounding wood.....kind of like worm tracks look to it, but in a pattern that looks like checking. I tend to think that whoever ends up with this platter, they are bound to notice it.......but to me, it really sticks out, because I know it's there! 😱 The wood itself seems solid enough......just bugs me! Ha! ooc

I have seen pitch in padauk. Our cherry often has this.
Some minor injury to the tree fills with ?sap? And it hardens turns black.
This can sometimes look like little black rices grains in the wood.
large pitch can be a structural issue. More solid than a bark inclusion.

Have a picture?

 

[Odie]

Have a picture?

I'll try to get a photo for this thread, but I'm off to work for now, and my son and I have plans for after work.......🙂

ooc

 

[Bill Boehme]

Oldie, I Googled padauk medullary rays and came up with some descriptions that could possibly be what you saw. The problem is that none of the descriptions included pictures.

 

[Odie]

OK, here it is.......VVVV

In the pic, they sure do look like cracks, and if you turn the bowl 180° to this lighting, they are almost invisible. I got the lighting just right to see them in this photo.

Can't see any separation, feel any separation, bend the platter slightly, and they don't open up.

I tend to think they are cracks, but they didn't show up (noticeably) with the original board. As stated, they were first noticed when the platter was close to final thickness. This was a kiln dried board about 3/4" thick and 7" wide. I looked at what was left of the board, and can't see anything in the board that looks like this, so if it showed up on the cut off piece, it was not very noticeable. I could have missed it, but tend to think the exterior of the board was in good shape.

ooc

 

[Bill Boehme]

That is very strange. I have no idea. Obviously, it isn't medullary rays. What appears to me to be the medullary rays are similar to those in white oak and have marked in a small crop from your image below. Basically, it is a rift sawn view of the ray while the view of the grain is a side view. Very beautiful platter, BTW.

 

[Odie]

That is very strange. I have no idea. Obviously, it isn't medullary rays. What appears to me to be the medullary rays are similar to those in white oak and have marked in a small crop from your image below. Basically, it is a rift sawn view of the ray while the view of the grain is a side view. Very beautiful platter, BTW.

View attachment 7598

Thanks, Bill......😀

You know, most checking occurs with the grain, and this is obviously across the grain. It may have been present in the live tree, and it may have had something to do with the kiln, or other processing. At first, I thought it was in the tree prior to any processing, but I'm not sure about that.....only guessing.

Then again, this may not be actual cracks, but something else entirely......? 😕

ooc

(off topic, but this forum really needs to get some good emoticons! )

 

[Charlie Knighton]

+1 on pitch, I agree with Al

 

[Steve Worcester]

I don't know about it being pitch, could be the tree was felled improperly causing the crack.
But a crack is a crack and dead trees don't heal.

 

[Tim L]

Although I am by no means an expert but the platter posted by Odie certainly looks like it has a crack to me.
Tim.

 

[Sergio Villa]

That is obviously a crack and in my opinion due to the stress in the wood. I see a change in the grain at the center of the crack possibly related to a knot. These are areas of different rigidity in the wood and when turning (vibration) or perhaps due to the thinness of the platter a crack may appear to relieve the stresses in the wood. The fact that it became invisible is not uncommon in my experience and perhaps this is due to the final state of equilibrium in the wood. It happened to me many times but the crack always become visible with a little saliva applied to the surface.

 

[John Tisdale]

Maybe a question for a botanist...

Odie,
Good pic - I'm assuming the anomaly is also present on the backside. Maybe the apparent "heal" is fused resins - as I type I realize that is a simplistic layman comment.

This would be a great question for Gene Wengert - anyone interested in drying and drying defects can benefit from the below white paper:

http://www.lignomatusa.com/images/Docs/LignomatPrinciplesPracticeDryingLumber.pdf

JOhn

 

[Odie]

Odie,
Good pic - I'm assuming the anomaly is also present on the backside. Maybe the apparent "heal" is fused resins - as I type I realize that is a simplistic layman comment.

This would be a great question for Gene Wengert - anyone interested in drying and drying defects can benefit from the below white paper:

http://www.lignomatusa.com/images/Docs/LignomatPrinciplesPracticeDryingLumber.pdf

JOhn

Hi John......"fused reins".....could be another term for "pitch"......? As for "fused", I can see how a trip through a kiln could harden some pitch and actually act as though the crack had been glued, or bonded......and, that seems like a very real possibility to me......

My choice of the word "heal" has caused a lot of confusion. Maybe "sealed" would have been a better word to use. Al's suggestion that this may be pitch, or maybe sap could be a possibility here.....that is, if the crack happened while the tree was still live. The staining or "haze" on both sides of the crack could be an indication of something filling in-between the crack and causing some staining. The consensus is that it is a crack, and at this point, I tend to agree. The question is when and how did it occur.....?

I'm going to rule out Al's suggestion that it's heat generated from a bevel rubbing. I know this can happen, but more likely with unseasoned wood and not with KD lumber, sharp tools, and a developed sense of tool handling.......so, the possibilities are the crack occurred while the tree was still live, when it was felled, being processed at the mill, or in the kiln. It doesn't appear as though we'll know the answer for sure, but I tend to think something penetrated and stained both sides of the crack. At this point, the pitch explanation seems like it is the most probable, which would indicate the crack was there while the tree was still live, and standing. The cause of the "across the grain" crack is a mystery, but it would seem this would be more likely when it was felled, in a kiln, or rough handling of logs and partially processed lumber.

Still only a guess, so anyone else's guess is just as good as mine........😕

ooc

 

[Richard Coers]

Almost certain that the only times you get cross grain cracking is from a rough landing when it was felled, or wind damage. Had that once in some mahogany.

 

[Bill Boehme]

If it is a crack then it seems reasonable that at least part of it should be visible from the other side. Can you detect anything similar on the other side? I have also been wondering if you heard any "odd" sound change. Just grasping at straws.

 

[Sergio Villa]

Here is a picture of a small vase made of hard maple. When I was decorating iT I did not see/notice the check, which, by the way is perpendicular to the grain and is not visible from the inside of the 1/4 inch wall. When I saw it it was barely visible, then it "disappeared" again to come back and stay with the vase for good. It is still not visible from the inside.

 

[Bill Boehme]

Looks like a catch to me. 😀



just kidding

 

[Odie]

If it is a crack then it seems reasonable that at least part of it should be visible from the other side. Can you detect anything similar on the other side? I have also been wondering if you heard any "odd" sound change. Just grasping at straws.

Yes, it does show up on the bottom, but not quite as much as from the topside. I looked at the platter under magnification this afternoon and cannot detect the crack.....only some discoloration. That's what you're seeing in my photo.

Here is a picture of a small vase made of hard maple. When I was decorating iT I did not see/notice the check, which, by the way is perpendicular to the grain and is not visible from the inside of the 1/4 inch wall. When I saw it it was barely visible, then it "disappeared" again to come back and stay with the vase for good. It is still not visible from the inside.

Sergio......As long as it doesn't go through to the interior, you could easily cover that crack with some creative wood burning. I see a comet, or shooting star going across the sky in your bowl......!😀

ooc

 

[Gerald Lawrence]

Here is a picture of a small vase made of hard maple. When I was decorating iT I did not see/notice the check, which, by the way is perpendicular to the grain and is not visible from the inside of the 1/4 inch wall. When I saw it it was barely visible, then it "disappeared" again to come back and stay with the vase for good. It is still not visible from the inside.

Have been reading this thread and what Sergio has found may be the case. Cracks and checks appear on the ends of dried lumber. These cracks have a terminal end , however the same crack may also go to the end of the board. I believe that drying causes these to expand or contract depending on the way the timber grew.
Also some on the cracks I have applied CA to on turnings have only shown up on the other side or a long way off after the application. So my point is that the crack may be a through and through or it may have stopped at a point inside the turning. I do agree that due to the jagged crossgrain nature of this line it is a crack. The strange part to me is that it should (in my experience) show worse after finishing.

 

[Bill Boehme]

The cracking on Odie's platter isn't one continuous crack, but a series of shorter cracks at slightly different levels. Earlier in the thread somebody mentioned damage when the tree was felled and I believe that is a very likely possibility. We will never know for certain, but because the cracks are mostly short and not all in a straight line it appears that there is still enough structural integrity to not "ring like a potato" as Mark mentioned in his test method for detecting cracks.

BTW, I had a small crop of potatoes in my garden this year and I'm still working on characterizing how they ring. Of course a thorough investigation involves trying different recipes to see if any don't ring true. So far, I like all of them. I'm glad that butter is no longer considered "bad" because it sure does go well with potatoes. 🙂