Bowl drying learning curve

[Chris Colman]

Since it is beginning to thaw out in my shop, I decided to unwrap and finish turn a couple of walnut bowl blanks that have been drying since last September.

I am new to turning green wood, so my learning curve is pretty steep right now.

Both bowl blanks had good sized cracks in them. Mostly in the rim and sidewall area.

I have been wrapping them in several layers of paper after roughing them to a consistent wall thickness. No DNA or other chemicals used. They were stored in my unheated garage shop over the winter.

Did the unusually cold weather have something to do with it? Did the way I had them stacked (nested like bowls) have an adverse effect on them? Is black walnut particularly difficult to dry successfully?

I would like to get this figured out before I carve up the other walnut logs into blanks.

Maybe some of you veteran SMC turners can give me a few pointers.

I know everyone has their own favorite method, and that none is guaranteed not to crack, but, what method have you had the most success with?

[Art Kelly]

I had the same thing happen to some big wet black walnut blanks. I stopped everything and Anchorsealed the end grain of the remaining blanks that hadn't yet cracked (two coats) and waited about a year. They cracked less than the first ones. Some didn't crack at all. Patience.

Not that there'e a magic formula. I cut some small red-maple ambrosia maple logs, carefully Anchorsealed them and put them in the garage. They all split, so I'll give them another while and make some little bowls out of blanks worked around the splits.

At the other end of the spectrum, I dug a Japanese Magnolia out of the ground the other day (it was alive but not well). It was soaking wet to the point of slinging water. I roughed them out to 80% or so and sat it in the kitchen. No cracks in two weeks.

Like Outback Steak House. "No Rules."

[Keith E Byrd]

I'm with Chris on this. Being new I turned a blank to about 90% and had in in a plastic bag - really sweating - I swapped bags a couple of times to get the bowl in a dry bag. Then I put it in two paper bags and left it in the house. It cracked. Bad.

[Steve Vaughan]

I'd guess that different woods are going to react differently to cracking. Usually, I rough-turn my blanks to 90% and then soak them in DNA for anywhere from a few hours to overnight. Then I take them out of the soak and put them into a paper grocery bag packed lightly with the shavings, tape it shut, and sit over in a corner somewhere. After about a month, I'll empty the shavings out, and wrap it back up in the paper bag for a few weeks and check on it. Very few problems with cracking.

[Michelle Rich]

Water freezes under 32 degrees F, whether it's in a glass or in wood. That will make them crack. If I were you I'd go to my local library and get out some turning books. They will have all sorts of info on how to store wood. Good luck!

[David E Keller]

Some photos might be useful, but I'm wondering if there's any pith left near the rim... That will almost certainly lead to cracking.

I've used DNA soaking with success for the most part, and I've been using plastic wrap to cover the outside of the form. The next batch of rough outs will likely get a coat of anchor seal on the outside instead of plastic wrap(I have lots of issues with geting the plastic to stay wrapped).

[Dennis Ford]

I often use the brown paper wrap method and rarely have trouble. Storing them nested may have contributed to the problem, that may have allowed the edges to dry much faster than the center sections. As important as the storage is the preparation; wall thickness = 10% of diameter, no pith, no sharp corners and no existing cracks. For more difficult woods, I coat the blank completely with Anchorseal (takes much longer to dry).

[Dale Bright]

My rough turning and drying methods have worked well for me. I have rough turned approximately 300 forms and bowls over the past 4 years and I have only lost one to cracks and splits. I have had some others split and crack but not so badly that I could not finish turn them.

My usual method it to rough turn to around 10% and completely coat in Anchor Seal. I put the rough outs on a shelf in my shop / garage, near the floor and out of any direct sunlight. The one that I lost is a 14 inch cherry bowl that I roughed out this past Nov. It had 2 large knots near the rim and I should have known better but I tried it anyway. It is not dry enough to finish turn yet but I checked it yesterday and it is beyond help.

On some of my end grain hollow forms, I just coat the end grain with Anchor Seal and put them into a paper bag. They go to the same shelf as the others. I check them all every 2 weeks or so.

The 2 turners that taught me this method have both been turning for more than 15 years and are both full time turners. They claim to lose less than 5% to splits while drying. We live in Virginia where it is not very dry and the weather and humidity where you live will have a great effect on the drying process.

Dale

[Ken Whitney]

I experienced much the same thing with lots of big cracks using the paper bag method.

I switched to DNA and have had much better results, although I still get occasional catastrophic cracks (i.e. unusable blanks). I also wrap the outside of the blank with stretch wrap, leaving the inside of the bowl exposed (I think Reed Gray has used that technique as well). I peel the stretch wrap off after a couple of weeks.

I just roughed out a couple of dozen maple and red willow blanks, DNA soaked and stretch wrapped, and so far not a crack in the bunch. Both of these trees were winter cut, and perhaps the moisture content of the wood was initially lower due to that.

There are so many variables (wood species, initial moisture content, humidity during drying, soaking medium, wraps, magic :)) to drying wet wood that I suspect one size does not fit all.

I would keep trying various methods until you find one that works the best.

[Bernie Weishapl]

I also use the anchorseal method. I turn mine to 10% thickness and coat the whole bowl or HF with anchorseal. I store them in my shop in a cool dry place with not much air movement. I store them on the floor and no more than 3 ft off the floor. Mike Mahoney told us at a demo this is how he dries his bowl, etc. It does take longer. Some up to a year. So far in the last 1 1/2 yrs of using this I have only lost one apple bowl. I try to keep a string of rough outs going so as I return the dry ones for finish I rough turn a couple of green blanks just to keep a supply going.

[Michael Mills]

I use the DNA method but also have some crack. Now after the DNA soak I coat the outside in an hourglass shape with Anchor Seal and place in a loose paper grocery bag.
I do coat the end grain around the tenon or inside wall of the dovetail. The DNA does seem to work and I go from 8-12 months to 8-12 weeks for the drying. Others have already mentioned, knock the sharp edge off the rim of the bowl and make sure the pith is out. I try to remove ½ to 1" from the pith. For me the biggest problem was leaving too much close to the pith, better to have a shallow bowl than no bowl IMHO.

[Reed Gray]

I use the plastic wrap on the rim of the bowl. I also turn to final thickness and let them dry and warp, and the more they warp, the more I like them. I tried the paper bag method, and it didn't work for me, I lost too many. Having the rim under the minimal compression that the plastic stretch film provides helped a lot (stretch film in 5 inch rolls at local office supply place, about 1 inch over the rim on the inside of the bowl, and the rest on the outside. I don't worry about the bottom). Rounding over your rims is another important step as a sharp edge will tend to crack much more readily than a rounded one, not to mention that it will cut you as the bowl is spinning on your lathe. If you had your bowls stacked one inside the other, that could have contributed to the cracking as in the rim area was drying, but the inside bowl area was sealed off and not drying as fast, making the drying stresses uneven. You do need some air space in between the bowls. Your local weather/humidity levels are another big factor as in things will dry much differently in Death Valley than they will here in the wet Pacific Northwest. Trial and error, plus talking to other turners in your area will help you solve this problem.

robo hippy

[mike caruso]

Hey guys my 4 brothers bowls were all turned to final thickness 3/16-1/4 sanded and sprayed heavey coat poly on outside rim and bottom and let to dry not much movement and only small cracking around knots ,But i have tried it with white and red oak and get alot of movement and cracks so of to the bath with my latest

[Wally Dickerman]

My rough turning and drying methods have worked well for me. I have rough turned approximately 300 forms and bowls over the past 4 years and I have only lost one to cracks and splits. I have had some others split and crack but not so badly that I could not finish turn them.

My usual method it to rough turn to around 10% and completely coat in Anchor Seal. I put the rough outs on a shelf in my shop / garage, near the floor and out of any direct sunlight. The one that I lost is a 14 inch cherry bowl that I roughed out this past Nov. It had 2 large knots near the rim and I should have known better but I tried it anyway. It is not dry enough to finish turn yet but I checked it yesterday and it is beyond help.

On some of my end grain hollow forms, I just coat the end grain with Anchor Seal and put them into a paper bag. They go to the same shelf as the others. I check them all every 2 weeks or so.

The 2 turners that taught me this method have both been turning for more than 15 years and are both full time turners. They claim to lose less than 5% to splits while drying. We live in Virginia where it is not very dry and the weather and humidity where you live will have a great effect on the drying process.

Dale

I sometime wonder why turners allow wood to crack when it's so easy to prevent it.

A wood sealer such as Anchorseal is the answer as Dale says. Actually, for most woods, after rough it out, I use a very liberal application of Johnson's paste wax. Been using the wax method for a lot of years,, on hundreds of pieces, and very seldom have a cracking problem. On the blank before turning I liberally coat it with Anchorseal. I've never used the DNA method. I do use brown paper bags along with the wax on very wet wood that is prone to crack such as fruit woods. Don't store wet wood in plastic bags for very long. It'll get mold stain.

Something to consider. When wood cracks after storing or turning it, usually the crack was already there. Just not very visable.

[Jack Mincey]

Something to consider. When wood cracks after storing or turning it, usually the crack was already there. Just not very visable
I agree with Wally on this one. Most cracks are in the wood when turned and they only get bigger as they dry. To take care of this issue I make a good clean finial cut on the last pass over the outside of a blank that is being roughed out and then look at the surface around the outside of the bowl. If you notice any small hairline checks already in the wood turn the blank down some more and check again. I have started with 14" blanks to end up with a 7" check free rough out at times. If I don't get rid of the check I through the blank out if it is not of a special piece of wood. If I try to save it I use supper thin CA on the hair line checks before I place it in the bag and keep my fingers crossed. I have a oak burl bowl that I saved in this manor and it had dozens of checks when roughed out. Consistent wall thickness is very important as well. Any where that the wall has a thick spot will cause more stress than you want as the bowl drys. I have dried hundreds of bowls over the last few years using nothing but brown paper bags laying them down on the floor of a back room to my shop that is unheated with very very few problems. I will still get the small checks around a knot but nothing that causes any great issue. Something I have to work with on my students bowls is that a lot of them want to turn bowls with walls that go straight down. This shape of bowl is much more prone to cracking the side wall than most. The shape of your bowl is another factor that needs to be considered to reduce cracking.
Happy Turning,
Jack

[Donny Lawson]

After rough turning the bowl to about 1" thick, I put some shavings from the turned bowl in a brown paper bag and put the bowl in the shavings and then add more shavings over the top of the bowl and then staple the bag shut. I write the date and type of wood on the bag and put it on a shelf.It dries well and so far I have never had a single bowl lost. The shavings will keep the bowl from freezing and draw moisture out. It's worked great for me.

[Mark Levitski]

Environmental conditions must be a huge factor in drying because I have had very good success with paper grocery bags, and I don't get too careful with methods of closing them. Also, with a full coating of Anchorseal my bowls would never dry--too slow for me. My shop is always at between 38-42% RH.

I agree that the best advice is to try different methods and to seek advice from local turners to match what works in your climate.

Mark

[Prashun Patel]

I've tried DNA but I'm with Dale and Bernie. Anchorseal + patience. You can make your own by melting paraffin or soy wax in mineral spirits. Equal parts of each works fine. It should be thin enough to brush on, but thick enough such that when it dries, it leaves a waxy film on the surface.

Also, you don't mention how the blanks were cut. Was there a lot of pith in them? You might still get minor cracking around pithy rims even if coated in wax. But I have yet to get a major crack in any of my blanks (I've got about 25 airing right now.)

[Scott Hackler]

When I started out I roughed to 90% and coated the whole blank with Anchorseal and stored them in an area with little sunlight and constant temperature. About a year later (give or take) the blanks were dry and ready for re-turning. Almost 100% success rate with no cracking and little warping.

But I have stopped doing that because I am impatient. It is extremely humid here in Kansas and drying them "naturally" will take me about a year (Anchorseal method). I switched to DNA soaking and wrapping tight with 3 layers of newspaper. I cut breather holes or slots in the newspaper by the form's opening. Sit them on the bottom shelf of the shop and 1-2 months later I have a dry, crack free blank. Works great for me, but this method doesn't float everyones boat.

My patience stems from my changing preference in forms. Bowls are fun, but I only turn them to relax because they dont "challege" me. If I wait a year to get a usable blank, I most likely wont care about that particular roughed out form.

[Chris Colman]

I appreciate all the advice and ideas, guys.

I think I will continue to wrap my blanks in paper, adding some shavings to moderate the drying rate.

I will try to stack them so air circulates all the way around, instead of nesting them like bowls in a stack.

Never thought about Johnson's paste wax, hmmmm....

The walnut logs these blanks came from were soooo wet, I was slinging water during the rough turn. I still have some logs that have been drying out all winter, hopefully they have dried a bit more.

Thanks again for the help. Somebody ought to sift through the posts on SMC and compile the tips into a book. It would be great!

[Leo Van Der Loo]

I dry my bowls in the brown paper bags, and done a few thousand bowls, I never use any shavings as this proved to start fungus growth when I did try this many years ago.
Also I set my bowls on edge so not to have one part unable to dry by it sitting against another bowl or floor/shelve/bench.