# help please: cracks after hollowing end-grain



## duncsuss (Jan 2, 2013)

Are there things I can do to reduce the chances of end-grain forms cracking as the wood dries?

I'd only turned "bowls" face-grain until I got this beautiful milo from David G; hollowed out a couple of beakers/vases/wossnames from it, but a few days later I see they're both cracking at the base.

Both bases are quite thick -- meaning I didn't hollow all the way to the bottom because I wimped out -- about 1" thick (compared with the sides which are less than 1/4").

Thanks for any advice on how I might stop this getting worse, and how I might avoid it altogether in future.

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## cabomhn (Jan 2, 2013)

Are these still a little wet? Even if they might seem dry you would probably be best off taking them as soon as you are done with them on the lathe and bagging them in a paper bag with the form's own shavings making sure to get the shavings all inside and out. Then close the bag and store it and wait a month or two. I've done this with my end grain forms and I've never had any issues, even with the thicker base. Good luck!


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## Tim Carter (Jan 2, 2013)

I turn a lot of end grain hollow forms-here's a couple of ideas that may help you. CA glue will frequently stop the cracks and then you can fill them with something to either accentuate the cracks like stone or to hide them using sawdust or coffee grounds. When I end up with a thick base, I usually will turn the piece over on the lathe and hollow out the foot more deeply than I usually do to lessen the possibility of cracking and also to lighten the piece. You also can put the piece in a brown paper bag to slow down the drying process. Hope these ideas help.


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## duncsuss (Jan 2, 2013)

cabomhn said:


> Are these still a little wet? Even if they might seem dry you would probably be best off taking them as soon as you are done with them on the lathe and bagging them in a paper bag with the form's own shavings making sure to get the shavings all inside and out. Then close the bag and store it and wait a month or two. I've done this with my end grain forms and I've never had any issues, even with the thicker base. Good luck!



Yes, chances are high that they're still wet. I don't have the shavings from them any more, but I've bagged them -- thanks!



Tim Carter said:


> I turn a lot of end grain hollow forms-here's a couple of ideas that may help you. CA glue will frequently stop the cracks and then you can fill them with something to either accentuate the cracks like stone or to hide them using sawdust or coffee grounds. When I end up with a thick base, I usually will turn the piece over on the lathe and hollow out the foot more deeply than I usually do to lessen the possibility of cracking and also to lighten the piece. You also can put the piece in a brown paper bag to slow down the drying process. Hope these ideas help.



I use CA when cracks develop in bowls as I'm turning them. I hesitated to do it with these because I find it stains the wood unless I spray with sealer (shellac) first, and I didn't know what would happen.

Thinning the base is an option, of course, but the weight gives them a stability that's kind of nice -- means I could put some dried flowers in them with less chance of them tipping over.

Thanks!


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## NYWoodturner (Jan 2, 2013)

Duncan - this is a lesson I continue to learn over and over - :dash2: If the wood still has a relatively high moisture content there will be a lot of movement in drying. With a different thickness at the bottom than the walls, the wood will dry at different rates, thus moving at different rates and distances. It is the equivalent of locking on two pair of vice grips and turning them different ways. 

This is a piece of maple that was sitting on the mantle after it came off the lathe. It wasn't done yet - I sometimes like to study a piece for a few days and make sure I'm good with it before I put the finish on. About three days in while we were watching TV this thing went and sounded like a .22 sent off on the room. Scared the hell out of 4 sleeping dogs.  Not to mention Gail... 

[attachment=15625]


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## Wildthings (Jan 2, 2013)

WOW


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## DKMD (Jan 2, 2013)

I've had success with bagging, but I hate trying to remember what's in all the bags laying all over the shop. Lately, I've been wrapping the outside of my forms with plastic stretch wrap to slow moisture loss from the outside of the form... I'm trying to get the pieces to dry from the inside out. You will need to watch for mold growth if the wood is pretty wet. I've also used lacquer or shellac to 'seal' the outside if the piece which seems to help. A lot depends on the type of wood and the humidity and temperature in your shop, too.


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## duncsuss (Jan 2, 2013)

Wildthings said:


> WOW



:whs:

Yeah, I can imagine that would raise my blood pressure a couple of points :wacko1:

From what you say, it sounds like there isn't a simple solution to this, and it's mostly down to luck.

Would it help to paint the end-grain with Anchorseal to slow the drying (as if it were a freshly-cut log)?


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## duncsuss (Jan 2, 2013)

DKMD said:


> I've had success with bagging, but I hate trying to remember what's in all the bags laying all over the shop. Lately, I've been wrapping the outside of my forms with plastic stretch wrap to slow moisture loss from the outside of the form...  I'm trying to get the pieces to dry from the inside out. You will need to watch for mold growth if the wood is pretty wet. I've also used lacquer or shellac to 'seal' the outside if the piece which seems to help. A lot depends on the type of wood and the humidity and temperature in your shop, too.



I'm blessed with a decent supply of Sharpie pens, makes it much easier to remember what's inside the bags 

When this wood arrived, it already had a little mold growing on one end (David had wrapped it in cling wrap for shipping), I wouldn't want that after I'd turned it.

I think I'll try spray-on shellac (or "sanding sealer", as Zinser like to call it) next time.

Do you normally rough-turn then wait for it to dry out before final turning? I do that with regular bowls, it didn't cross my mind that I might have to do it with end-grain forms too.


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## DKMD (Jan 2, 2013)

duncsuss said:


> DKMD said:
> 
> 
> > I've had success with bagging, but I hate trying to remember what's in all the bags laying all over the shop. Lately, I've been wrapping the outside of my forms with plastic stretch wrap to slow moisture loss from the outside of the form... I'm trying to get the pieces to dry from the inside out. You will need to watch for mold growth if the wood is pretty wet. I've also used lacquer or shellac to 'seal' the outside if the piece which seems to help. A lot depends on the type of wood and the humidity and temperature in your shop, too.
> ...



I've done both(twice turned and green to final thickness)... Even walls are the key to increased success in drying, and slower almost always works better than faster. The anchorseal is great if you're gonna twice turn, but I wouldn't use it otherwise. You could use pastewax to try and slow the drying on a green piece if you don't mind a straight wax finish.


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## duncsuss (Jan 2, 2013)

DKMD said:


> I've done both(twice turned and green to final thickness)... Even walls are the key to increased success in drying, and slower almost always works better than faster. The anchorseal is great if you're gonna twice turn, but I wouldn't use it otherwise. You could use pastewax to try and slow the drying on a green piece if you don't mind a straight wax finish.



Thanks again


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## Mike Mills (Jan 3, 2013)

I seal the endgrain with anchorseal as I feel it has some "give" or flex.
Shellac may work but I would think it (the shellac) would be more prone to cracking also.


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## duncsuss (Jan 3, 2013)

Mike Mills said:


> I seal the endgrain with anchorseal as I feel it has some "give" or flex.
> Shellac may work but I would think it (the shellac) would be more prone to cracking also.



Mike -- just so I understand, do you use Anchorseal ...

1) if you're rough turning then setting it aside to dry?

2) if you're turning all the way to completion and then letting it dry?

I use it on raw-cut wood myself, but had never though it necessary to use on either rough-turned or finish-turned items. (Till now, that is.)

Thanks


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## Mike Mills (Jan 3, 2013)

duncsuss said:


> Mike -- just so I understand, do you use Anchorseal ...
> 
> 1) if you're rough turning then setting it aside to dry?
> 
> 2) if you're turning all the way to completion and then letting it dry?



I anchorseal the outside bottom and up about an inch on the sides; then the very top edge. Then bag to dry.
I have never turned complete from green on an end grain item.

I don't turn many hollow form types and when i do they are typically under 6" tall.

Sorry it took so long to reply.


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## Kevin (Jan 4, 2013)

Wet ERC cracks exactly like that. I started sealing all rough turns with two coats of log sealer inside and out and all over. I haven't had a single crack since doing this and no mold grows on them if you don't bag them. Just set them on a shelf out of sunlight.


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## duncsuss (Jan 4, 2013)

Kevin said:


> Wet ERC cracks exactly like that. I started sealing all rough turns with two coats of log sealer inside and out and all over. I haven't had a single crack since doing this and no mold grows on them if you don't bag them. Just set them on a shelf out of sunlight.



Thanks Kevin ... is "log sealer" the same as Anchorseal?


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## Kevin (Jan 4, 2013)

Yes AS is a brand made by UC Coatings. I prefer AS2 it's thicker than the original formula which I didn't care for very much.


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## duncsuss (Jan 4, 2013)

Kevin said:


> Yes AS is a brand made by UC Coatings. I prefer AS2 it's thicker than the original formula which I didn't care for very much.



I'm not sure what kind of Anchorseal I've got -- the turning club bulk-buys and resells it to members at less than half the retail price.

Thanks again!


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## Kevin (Jan 4, 2013)

The old formula does still work. Especially at half price.


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## Mike Mills (Jan 4, 2013)

I think Kevin is right for the most protection. I have a brother who lives in El Paso; he was visiting and I gave him a bowl that had been finished about 6 months. In less than a month it busted wide open in El Paso. It can be at equilibrium here in NC and drop 8% in a move to El Paso.

Charlotte 11.9-13.8 El Paso 5.8 - 9.6

http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf


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## dean jordan (Jan 7, 2013)

Let me jump in with my biasis. Anytime you havuneven thickness you increase your chance of cracking.The thin wood loses moisture much faster than thick. I have found two things that can help.The first is to turn even thickness of wood. If you are going to turn thick and let dry your thickness should be 10% of the diameter from top to bottom.end grain dries faster than side grain so you should seal the end grain both top and bottom.The other thing I do is boil or steam the wood. I boil or steam 2hrs per in thickness.Then leave the wood in water until it cools off. then seal and dry. Check it every day to watch for cracks. boiling drives water out of the cells and a1in thck piece will be pretty dry in 5to 7 daks.No paper bag needed.Even if I turn to final thickness green. steaming or boiling reduces cracks and movement. I can sand in 1wk or less depending on the thickness.hope this helps


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## duncsuss (Jan 7, 2013)

dean jordan said:


> Let me jump in with my biasis. Anytime you havuneven thickness you increase your chance of cracking.The thin wood loses moisture much faster than thick. I have found two things that can help.The first is to turn even thickness of wood. If you are going to turn thick and let dry your thickness should be 10% of the diameter from top to bottom.end grain dries faster than side grain so you should seal the end grain both top and bottom.The other thing I do is boil or steam the wood. I boil or steam 2hrs per in thickness.Then leave the wood in water until it cools off. then seal and dry. Check it every day to watch for cracks. boiling drives water out of the cells and a1in thck piece will be pretty dry in 5to 7 daks.No paper bag needed.Even if I turn to final thickness green. steaming or boiling reduces cracks and movement. I can sand in 1wk or less depending on the thickness.hope this helps



Thanks for these thoughts. One difficulty I have is reconciling these ideas:

(1) the objective is to have uniform rate of drying
(2) thin wood dries faster than thick wood
(3) end grain dries faster than side grain
(4) turn the wood to uniform thickness to get uniform rate of drying

Point #4 fits well with point #2 but appears to ignore point #3 ...


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## dean jordan (Jan 8, 2013)

duncsuss said:


> dean jordan said:
> 
> 
> > Let me jump in with my biasis. Anytime you havuneven thickness you increase your chance of cracking.The thin wood loses moisture much faster than thick. I have found two things that can help.The first is to turn even thickness of wood. If you are going to turn thick and let dry your thickness should be 10% of the diameter from top to bottom.end grain dries faster than side grain so you should seal the end grain both top and bottom.The other thing I do is boil or steam the wood. I boil or steam 2hrs per in thickness.Then leave the wood in water until it cools off. then seal and dry. Check it every day to watch for cracks. boiling drives water out of the cells and a1in thck piece will be pretty dry in 5to 7 daks.No paper bag needed.Even if I turn to final thickness green. steaming or boiling reduces cracks and movement. I can sand in 1wk or less depending on the thickness.hope this helps
> ...


not necessarily.thin end grain and thick end grain dry faster than side grain.Think of wood cells as straws where air can enter from the end and not so much from the sides. Thats why logs crack on the ends first. As cells lose water they get smaller and try to shrink.The uneven stress from dry wood to wet wood is what causes the cracks, as the stress actually tears the wood cells apart.Try it I think it will help.The picture from nywoodworker is a perfect example look closely at the difference of wall thickness it was a setup or cracking If i am working on a nice piece and cant finsh turning to thickness I put it in a garbage can of water to keep it from drying. I put a little chlorine in to keep things from growing on the wood.


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