What's the best way to prevent cracks in black and white ebony?

[Odie]

Right now, there is some very nice black and white ebony bowl blanks on the Cook Woods site. I should know better than to buy any, because I've turned several pieces in the past......and, they all had severe cracks. I know this species has this very common problem, so, I have been warned! Anyway, I purchased one piece last June 18th, and after about a week of acclimating, I rough turned this piece two days ago. This one is 7x2. I intentionally left the wall thickness very thick, hoping that would prevent cracks.....but, yesterday I had cracks developing. (A thick coating of anchorseal was brushed on after roughing out.) Yesterday, I put epoxy in those cracks, and new cracks developed overnight. The original cracks seem to have not gotten any worse, and I suspect the epoxy stopped them from spreading. This morning, I applied more epoxy over the entire areas of the inside where the cracks were accumulating......hoping it would seal the surface, and any moisture release would seek other areas to disseminate, where there was less likely to cause problems. The MC on the bowl block was approximately 34%. So far, there is no cracks developing on the exterior, and all the cracks are on the end grain of the interior.

It seems to me that when a crack develops, it exacerbates the problem, because that is the point where the most moisture will escape. If the moisture release at that particular point can be prevented, then the crack won't get worse......that's my best guess.

I'm seeking any input from those who have worked black and white ebony......especially if they have prevented cracks from forming, or successfully halted any from getting worse.......

Is it possible, the best way to handle this species, is to store the original block for many years, prior to ruffing out?

-----odie-----

 

[hockenbery]

Even Wall thickness, shape with curves that lets the wood move and controlling the drying determine the successful percentage.
Larger bowls and woods with much larger tangential shrinkage than radial shrinkage demand even walls and curves that can move.

A side view would help

 

[Ed Davidson]

I always thought that...like Snakewood, B&W Ebony cracks were related to heat build-up from sanding. I could be wrong, but very light sanding has worked in the past for me.

Here's an end-grain faced yo-yo, turned last year...no cracks

 

[Glenn Lefley]

I found that you go from thick to relatively very even thin. And then it won’t crack . if you leave it rough turned first time thick will crack every time.

 

[Bill Boehme]

Some tropical wood will crack no matter what. I had an eight inch blank of some unknown South American wood that I kept for at least five years and it seemed to be continually opening up new cracks. When it appeared to finally be stable I turned it and within a couple days there new cracks.

I think that the issue with many oily tropical species is case hardening combined with significant radial shrinkage as the wood dries. Case hardening in wood happens when the relatively thin layer wood close to the surface dries, but the interior of the wood is still very wet. As the deeper wood loses its free water and begins to lose bound water, it starts shrinking radially and that forces the outer dry layer to split. It's hard to avoid case hardening in some tropical species, but it helps if you can slow down the drying process to a crawl. You might be able to prevent cracking by turning the wood very thin if you are willing to accept a lot of warping. One problem area that I see are sharp corners ... between rim and body of bowl as well as outer edge of the rim. Also, the bowl has steep sides and a fairly broad flat bottom.which will lead to differential shrinking as the wood dries.

Ed Davidson mentioned heat buildup while sanding and that is probably the most common way to cause case hardening.

One trick that the late Jim King of Peru used to use was boiling the wood after rough turning.

 

[Odie]

Well, it certainly has been a frustrating experience with the bowls I've turned out of black and white ebony. So far, so good.......I just checked again, and see no further movement of the sealed cracks. It does appear the secret is to seal off all air flow in the area where the cracks are generating......and, that's because of the epoxy seal, I think. It's still early, and I'm not assuming I have stopped the cracks. I'll continue to closely monitor this bowl in the coming months. The wall thickness at the rim is about 1 1/8" tapering down to about 7/8" at the very bottom of the interior. I'll revive this thread if there is any new news on it. The seasoning process, because of the 34% MC and extra thick walls, is likely to take a year to stabilize.....

-----odie-----

 

[Odie]

According to the wood database:

Workability: Generally works and turns well, though pieces can be difficult to dry without checking.

Out of the 40,000 bowls offered on Etsy, there were no black and white ebony bowls. (There was one that was laminated out of smaller pieces, though.)

The last black and white ebony bowl I made (several years ago) actually sold on Etsy to a collector buyer who was anxious to acquire it, even though he knew it had epoxy filled cracks. This one, I wasn't closely monitoring, other than the usual visual inspection during monthly weights while seasoning. I can remember being shocked how quickly the cracks appeared, and how deep the cracks were. My only option was an epoxy fill on the finished piece. I was surprised to find someone who wanted it so adamantly, that he was willing to overlook the cracks!

That one was 7 5/8" x 3 1/8", and was roughed to a standard 1/10th diameter (a bit bigger than the current one)......took about 17 months to stabilize it , and the initial reading was 26% MC.

You can see the huge epoxy filled crack in the 2nd photo here:

-----odie-----

 

[Lamar Wright]

According to the wood database:



Out of the 40,000 bowls offered on Etsy, there were no black and white ebony bowls. (There was one that was laminated out of smaller pieces, though.)

The last black and white ebony bowl I made (several years ago) actually sold on Etsy to a collector buyer who was anxious to acquire it, even though he knew it had epoxy filled cracks. This one, I wasn't closely monitoring, other than the usual visual inspection during monthly weights while seasoning. I can remember being shocked how quickly the cracks appeared, and how deep the cracks were. My only option was an epoxy fill on the finished piece. I was surprised to find someone who wanted it so adamantly, that he was willing to overlook the cracks!

That one was 7 5/8" x 3 1/8", and was roughed to a standard 1/10th diameter (a bit bigger than the current one)......took about 17 months to stabilize it , and the initial reading was 26% MC.

You can see the huge epoxy filled crack in the 2nd photo here:

-----odie-----
View attachment 29851 View attachment 29852

Howdy Odie.....Very nice save on this ebony bowl. Was just wondering, did you use anything mixed in with the epoxy (sawdust) ? Very nice job indeed!

 

[Odie]

Howdy Odie.....Very nice save on this ebony bowl. Was just wondering, did you use anything mixed in with the epoxy (sawdust) ? Very nice job indeed!

Good mornin' Lamar......No, didn't mix anything in with the epoxy, although I should have. I was very unsatisfied with the repair, and it's one of the reasons I was a bit surprised that someone wanted it. (It may be that the success rate for making bowls out of black and white ebony is quite low, and could be the reason why my collector customer was willing to overlook the obvious error/repair.....?) If I had it to do over, I don't think I'd even list it in my Etsy shop......because, I'd rather give it to someone than risk damaging my reputation on there.

On the current black and white ebony bowl, I've caught these cracks when they were small, and the roughed bowl is probably thick enough to eliminate them on the final turning......we'll see about that. My success or failure on this bowl will probably be the key to whether I'll ever bother with making bowls out of B&W ebony again.......might be more suitable for a yo-yo or a pen, but the stresses and variables of bowl making, combined with the success rate, and expense, might just be too much to ask of this otherwise very beautiful wood......

-----odie-----

 

[Odie]

On the current black and white ebony bowl, I've caught these cracks when they were small, and the roughed bowl is probably thick enough to eliminate them on the final turning......we'll see about that. My success or failure on this bowl will probably be the key to whether I'll ever bother with making bowls out of B&W ebony again.......might be more suitable for a yo-yo or a pen, but the stresses and variables of bowl making, combined with the success rate, and expense, might just be too much to ask of this otherwise very beautiful wood......

Update:......33 hours later, and the cracks appear to have stopped getting worse. No new cracks. I don't think any moisture can escape through the epoxy. I don't know If I can dare feel at ease with this bowl.....but this is promising !

-----odie-----

 

[hockenbery]

don't think any moisture can escape through the epoxy.

If that is true it cannot dry.

When I dry bowls in paper bags in 50% humidity they take 6-8 months
When I dry bowls coated with anchor seal in 50% humidity they take 8-12 months to dry
Both slow the drying by letting the moisture out slowly. The anchor seal more slowly.

If no moisture gets out the bowl can’t dry.

A guy in our club turns sinks and finishes them with epoxy. It makes them waterproof.

 

[Bill Boehme]

I think that Odie's point is that it is sealed well enough to prevent cracking, but obviously the entire piece would have to be encapsulated in epoxy to stop all moisture loss in the wood. As Odie said moisture can't escape through the epoxy, but it can migrate through the wood and eventually escape where the wood is not coated with epoxy. So, in effect this looks like another way to greatly slow down the drying and minimize cracking.

 

[Odie]

I think that Odie's point is that it is sealed well enough to prevent cracking, but obviously the entire piece would have to be encapsulated in epoxy to stop all moisture loss in the wood. As Odie said moisture can't escape through the epoxy, but it can migrate through the wood and eventually escape where the wood is not coated with epoxy. So, in effect this looks like another way to greatly slow down the drying and minimize cracking.

Yes, correct, Bill......Since this is entirely theoretical, and I'm testing something that I'm not aware has been done, or established.....I'm waiting this one out to see what kind of results I can get. Since the epoxy is only on a small patch where the cracks are appearing, and as you hypothesize......hopefully the moisture will find another path of escape.

I was hoping to connect with someone who has successfully prevented existing cracks on B&W ebony roughed bowls from getting worse.....maybe someone will come along and offer some other solutions for seasoning this difficult wood, because I certainly have not been very successful with it.

-----odie-----

 

[Glenn Lefley]

Even the wood database says it’s difficult to dry without checking!

 

[Bill Boehme]

Odie, I saw this B&W ebony turning blank on the Cook woods site. Despite all the defects they mentioned, the price seemed to be rather stiff.

 

[Gerald Lawrence]

Odie I have a question. Did you coat the area of cracking or did you only fill the cracks?

 

[Odie]

Odie, I saw this B&W ebony turning blank on the Cook woods site. Despite all the defects they mentioned, the price seemed to be rather stiff.

Yeah......that one does seem expensive to me, too. The figuring doesn't look all that great, either. The bowl blank I'm currently working with was 7x2, and I paid $99. Even that was a bit hard to swallow, but I looked over all these blanks, and picked one out that I felt was the best figure of the bunch.....within what I was willing to pay.

-----odie-----

 

[Odie]

Odie I have a question. Did you coat the area of cracking or did you only fill the cracks?

Gerald......The first application of epoxy was only on the existing cracks. The next day, when more cracks were appearing, I coated the entire areas where the cracks were appearing. I used a finger cot to force the epoxy into the cracks, and spread the epoxy over the surface area. The entire surface had anchorseal already there......pretty messy, but I'm hoping most of these cracks can be turned away on the 2nd turning.....providing, of course, they can be prevented from getting any worse than they already are.

(Note: For those of us who have had a manual prostate exam, you will know what a finger cot is! )

-----odie-----

 

[Owen Lowe]

I was hoping to connect with someone who has successfully prevented existing cracks on B&W ebony roughed bowls from getting worse.....maybe someone will come along and offer some other solutions for seasoning this difficult wood, because I certainly have not been very successful with it.

This doesn't really help your current situation -- and not exactly B&W ebony -- but...

The rare times that I buy really expensive exotics, like bowl blanks of blackwood, bloodwood, and cocobolo, I never turn them for a couple of years. I scrape off the surface wax and put them on the shelf and try my best to forget about them. The storage shelves for these blanks are in a cool basement with minimal air movement nearby.

Then, when I go to turn one of them, I take it in steps and always paper bag the piece. For example, rough out exterior and interior > paper bag for a month or two with frequent checking. If I see any cracks starting I put it in a plastic bag for another couple months. I know this sounds extremely laborious and tedious but it has worked for me.

Bottom line for me is that I rarely buy such woods because they are so prone to self-destructing given the money spent.

 

[robo hippy]

I am wondering if the Christian Burshard method of drying Madrone would work. He puts the fresh turned piece in a paper bag, then puts that inside a plastic bag. The paper bag is changed out daily. I think the #1 rule for drying is 'if you dry it too fast, you get cracking'. #2 is 'if you dry it too slow, you get mold.' I don't turn pieces like that, but my green turning methods might work, by turning to final thickness, and with the exotics, I would probably try wet sanding with oil, walnut of wipe on poly. Not really sure...

robo hippy

 

[Owen Lowe]

I am wondering if the Christian Burshard method of drying Madrone would work. He puts the fresh turned piece in a paper bag, then puts that inside a plastic bag. The paper bag is changed out daily. I think the #1 rule for drying is 'if you dry it too fast, you get cracking'. #2 is 'if you dry it too slow, you get mold.' I don't turn pieces like that, but my green turning methods might work, by turning to final thickness, and with the exotics, I would probably try wet sanding with oil, walnut of wipe on poly. Not really sure...

robo hippy

My method is the definition of slow drying!

I wonder how the exotics would respond to boiling... it's something Dale Larson does with his Madrone bowl rough-outs. For those not familiar with madrone, it exhibits very large shrinkage rates (12% tangentially, 18% in volume) and will crack if left to any thickness. I believe this is why Christian develeped his thin-walled vessels that warp significantly. Boiling seems to relax the connective fibers so that the wood distorts more easily as it dries.

 

[Odie]

Thanks Robo and Owen.......

Thanks to you, and a few others, I have some other avenues to pursue. I checked on the b&w ebony bowl a short while ago, and I'm not seeing any new checking, or existing cracks that have gotten worse. Still have my fingers crossed, and I'm feeling fairly good about things, so far. I'm surely not out of the woods yet. if this method doesn't work out for me, then I'll check back on this thread to try something else.....next time. On this one, I'm pretty much committed to the current method of seasoning. I have a pretty good success rate with all other woods, including other exotics.....but, this b&w ebony has always been a problem wood for me.

Only thing to do is wait and see for now.......could take an extended period of time to have answers, though!

-----odie-----

 

[Odie]

Update:

I just finished my monthly weights on the roughed bowls I'm currently seasoning. The B&W Ebony bowl has lost 2oz, and it appears the cracks have not gotten any worse. (yay!) Filling the cracks with epoxy seems to be the trick to stopping them. The cracks are small and I'm betting, for the most part, they can be turned away on the final turning. We'll see.....still a long ways to go to reach equilibrium.

edit: I caught the cracks early, because I have some experience with turning B&W ebony.....and, know about the problems with this wood. I monitored this one very closely. On the previous bowls I've turned from this wood, I didn't notice the cracks until the next months weight......now, I know better!

I'm thinking the epoxy creates a barrier that does not allow moisture to penetrate, and whatever is beneath the surface there, will eventually be expelled elsewhere......

Not sure there is a way to prevent cracks from forming from the get-go, because there really isn't a way to know for sure where they will be. I suppose you could epoxy the entire area, but that seems to defeat the object of seasoning.....

-----odie-----

 

[Odie]

Update:

The B&W ebony bowl has warped quite a bit, but the epoxy filled cracks appear to be working quite well, and haven't noticeably gotten worse since the initial roughing. (My hypothesis that the moisture will find other avenues of escape, other than from the cracks themselves, creating an airtight barrier, seems to be proving true.) As it is right now, it measures 7" x 6 5/16" at the diameter, and has lost about 7oz since it was roughed and anchorsealed. Initial MC was 36%.....very wet.....and, it's still losing weight on a month by month basis.....so it still can't be considered stabilized yet.......

It appears as though this bowl will be a success, but it ain't over yet.....

-----odie-----

 

[Karl Loeblein]

Odie,

Here's a thought: Ebony is too expensive to test out different drying techniques like turning thin, kiln drying (slowly), boiling, and soaking in DNA or Dish Soap. I wonder if you could run test on Persimmon wood instead since it's in the Ebony family but much cheaper.

-Karl

 

[Odie]

Odie,

Here's a thought: Ebony is too expensive to test out different drying techniques like turning thin, kiln drying (slowly), boiling, and soaking in DNA or Dish Soap. I wonder if you could run test on Persimmon wood instead since it's in the Ebony family but much cheaper.

-Karl

True, Karl........However, this particular B&W Ebony bowl wasn't intended to be a "test" specimen.......it was an attempted "save" for a bowl that was developing cracks after roughing and anchorsealing. Something HAD to be done with this one.....or lose it.

I am so pleased that this appears to be working out well.......as you say, this wood is just too expensive to use it for testing purposes.....and I agree with that assessment wholeheartedly.

Since it appears to be successful, I'll be using this method for any cantankerous woods I come across in the future.......provided, of course, that it is indeed successful in the final result......and, THAT is yet to be determined.

-----odie-----

 

[Charlie Knighton]

Do you use black epoxy?

 

[Odie]

Do you use black epoxy?

No Charlie.......all I have is clear epoxy......hoping most, or all of it will be turned away on the second turning........

-----odie-----

 

[robo hippy]

I know others have tried it, and I guess results are highly variable. I have a number of madrone blanks that are more spindle type blanks, up to about 3 inch diameter. Madrone loves to crack, in part due to very high water content so it shrinks more than other woods when drying. I coated the ends with Titebond glue. Thus far, no cracks after about a year. In theory, the glue is permiable so water can go out. I would think that the epoxy would not be like that and would tend to seal in the water. Not sure if that would help or not. I can't remember if the ebony is an oily wood or not. I would be skeptical about burying the bowl blank in a dessicant (spell??) which would some what protect the wood as it dries out. Only other solution I can think of would be a vacuum kiln, but that is science beyond what I know. It does a better job of drying madrone than the standard kilns, but still the process needs to be refined for each different type of wood...

robo hippy

 

[Odie]

Well, after 15 months, the black and white ebony bowl has finally stabilized, as of the first day of August. I weigh and log the information on all the bowls that are in the process of seasoning on the 1st day of each month. Currently, there are about 50 roughed bowls in the process.......

The b+w ebony bowl warped and shrunk severely, and went from 7" diameter to 6", and ended up with usable stock after re-truing it!......that's a lot of shrinkage!

The epoxy fills in the cracks worked wonderfully to arrest the progression. I'll definitely use epoxy to prevent air release around the cracks, if I ever have the opportunity to do a similar bowl. The epoxy seems to be a complete barrier to moisture release.....and, that is what was needed here. I was able to eliminate all the existing cracks on completion of the bowl.

The bowl is a success!

-----odie-----

 

[robo hippy]

SWEET!

robo hippy

 

[Brandon Sloan]

Glad it worked out, I’ve seen these expensive blanks. I’ve always wondered if they were viable for resale. Do you find that these types of projects are worth$$ the effort? I can see the enjoyment of turning different species, just trying to better understand the marketplace.

 

[Odie]

Glad it worked out, I’ve seen these expensive blanks. I’ve always wondered if they were viable for resale. Do you find that these types of projects are worth$$ the effort? I can see the enjoyment of turning different species, just trying to better understand the marketplace.

Yes, they are viable for resale, because there are collectors out there who are looking for examples of exotic woods for their collections. This doesn't mean you'll automatically find a buyer, because you still have to compete with other turners. Now, this particular wood black-and-white-ebony species appears to be quite rare in a finished bowl form, so the buyer might be easier to find with this species. I expect other turners will have the same problems with cracking and warping that I have, and many of the available chunks of wood will end up as failures.....so, the number of finished pieces being offered in the marketplace, may be somewhat limited in bowl forms.

You are correct that I do consider some of these "overpriced" exotics to be a challenge, and when something comes up that I haven't turned before, I usually get it......just to know how it turns, and finishes.......there is a bit of a gamble in turning some of them.....and, to be quite honest, a turner might be better off to consider the enjoyment of turning something rare and different, than to just consider the financial aspects of it's value to you!

-----odie-----

 

[Brandon Sloan]

Yes, they are viable for resale, because there are collectors out there who are looking for examples of exotic woods for their collections. This doesn't mean you'll automatically find a buyer, because you still have to compete with other turners. Now, this particular wood black-and-white-ebony species appears to be quite rare in a finished bowl form, so the buyer might be easier to find with this species. I expect other turners will have the same problems with cracking and warping that I have, and many of the available chunks of wood will end up as failures.....so, the number of finished pieces being offered in the marketplace, may be somewhat limited in bowl forms.

You are correct that I do consider some of these "overpriced" exotics to be a challenge, and when something comes up that I haven't turned before, I usually get it......just to know how it turns, and finishes.......there is a bit of a gamble in turning some of them.....and, to be quite honest, a turner might be better off to consider the enjoyment of turning something rare and different, than to just consider the financial aspects of it's value to you!

-----odie-----

I agree with with you there. I get much more enjoyment from turning than financial gain. Just need to crack the code too get the two on the same plane.

 

[Dean Center]

Odie, with the current weather we've been having, it seems like it's been almost muggy at times. If the humidity level when it's 90 is 'high', there will be a big change by winter when it's super low. You should probably sell that bowl to someone in Hawaii or Florida as soon as possible.

 

[Charlie Knighton]

y'all need to fit & use 55 gal cardboard barrels

 

[Odie]

y'all need to fit & use 55 gal cardboard barrels

?....huh.......Sorry Charlie......I don't get your meaning here.

-----odie-----

 

[Charlie Knighton]

Storing wood in barrel cuts down on cracking.....prefer to put blanks in

 

[John Walls]

Storing wood in barrel cuts down on cracking.....prefer to put blanks in

Are these barrels filled with water or a mix of? Barrels made of plastic or wood?

 

[Charlie Knighton]

no water or other stuff....the blanks will sweat....key not opening the barrel for a couple months.....but I have opened to quickly add blanks...the furniture factories keep all kind of woods with barrels
barrels are 55 gal drums made of cardboard sides metaltops