Turning green wood bowls is one of the most satisfying experiences imaginable. Taking a freshly cut piece of timber and turning it into a form, a creation to enjoy, use, and admire, is the ultimate gratification.
Wood is an ever-changing, dynamic material. Raw timber, green wood, is the blank canvas of bowl turning. Whether it’s a small branch or an entire massive tree, all wood bowls start with some type of raw forest material.
And as woodturners, we need to understand this dynamic material to harness its possibilities and not become surprised or potentially humiliated by its realities.
It is up to us to apply our vision to see the potential that lies in each grain-filled specimen and bring it to a new life as a functional or decorative turned piece.
Wet and Dry
There are two broad categories of bowl blanks, green or wet wood and dried bowl blanks. As most woodturners don’t have access to kilns or dryers and purchased dried blanks are usually expensive, meaning more than free, we will be discussing the fine art of turning green wood bowls on the lathe.
Turning green wood is not without its drawbacks and quirks. In this article, I will share with you what I’ve learned about turning green wood bowls, both acquired knowledge and first-hand experience.
What is Green Wood
Before we go too far, it makes sense to define green wood. Some people, define green wood as only freshly cut wood that comes from a recently growing living tree. That type of green wood is usually dripping with moisture, especially if harvested in the spring or summer months.
Any wood that is not seasoned and noticeably moist is considered green wood. This may be wood from a just fallen tree or a log that has sat for some time. Wood can hold moisture for very long periods of time after being cut or downed.
This may sound silly, but virtually any wood that is wet and not dry is green wood. Wood that can still lose excess moisture is green wood. It’s really that simple of a definition.
Dry Wood Understanding
With either the passage of time or the use of a kiln, wood is dried or seasoned. When the amount of moisture in a particular piece of wood is reduced to the point where no more moisture can be moved out of the log, this constitutes dry wood.
Wood will become “dry” by letting it sit for a long enough period of time. A rule of thumb that is thrown around often is one year of air drying time per one inch of wood thickness.
A dryer or kiln can be used to reduce the moisture content more rapidly. Another alternative, a microwave can aide in this process by methodically heating the wood-locked moisture which forces it to escape in the form of water vapor.
Equilibrium
Did you notice the definition of dry wood above? “When the amount of moisture in a particular piece of wood is reduced to the point where no more moisture can be moved out of the log,” does not mean the wood is 100% moisture free. Why is this?
Everything everywhere is relative. Wood is somewhat like a sponge. It will absorb and release moisture forever. Yes, I said forever. Some woods do an excellent job making us think they are not moving and shifting because of moisture content, but they are.
Instead of thinking of “dry wood” as a static final resource material, think of it as a flexible, moving sponge. The cells in wood continue to absorb relative humidity in the air, and they also secrete moisture when the surrounding relative humidity is low.
Wood is a dynamic changing material that can be turned and made into beautiful creations, but we need to be mindful that it is not a static, fixed material.
Conditions and Climate
It would be really nice and straightforward to be able to say something generic and universal like, “once the wood is at a moisture content of, say, 12% it is then dry.” But, that may or may not be true for where you live, the season, or the type of wood you’re turning.
A wood bowl blank sitting on a shelf in North Carolina might be considered “dry,” while the same bowl blank sitting on a shelf in Phoenix may continue to lose moisture and change shape for some time. It’s all relative.
Moisture levels in wood are subject to change with the surrounding climate and conditions. Because of this, there is never a straightforward answer to the many questions that arise about the “drying” process of green wood. But there are many indicators that we can use as guides along the way.
Why The Fuss
What’s the big deal about moisture content? Moisture in the wood cells helps define the shape of those wood fibers. And if the form of those cells can be changed, the entire chunk of wood can, therefore, be changed as well.
When a fluctuation in a wood’s moisture content occurs, the wood moves. This movement can be subtle or dramatic. When the timber is cut, the tree can no longer move moisture the way it did when it was living. Basically, a cut piece of wood is exactly like a kitchen sponge.
If a kitchen sponge is wet, it expands and fills its cells with water. The same kitchen sponge left on the counter to dry will contract, shrink, and pull together in a tightly curled shape. Expanding and contracting is essentially what wood does as well, forever.
Cracking
The worst offender when turning green wood bowls is cracking. Cracks occur when the internal pressures in the wood structure dry unevenly. A bowl wall that was turned thin at the rim and thicker at the base cannot move moisture in and out evenly. This stress between too uneven regions usually causes cracking when the bowl is left to dry.
Cracking occurs based on the organic structure of the tree and the different areas in the log under various pressures, as well. The pith area of a log is especially prone to cracking. All the surrounding wood layers pull and push from this core.
While some cracks in wood bowls can be fixed, it’s usually best to try to avoid them all together in the first place. Even and consistent wall thickness when turning green wood is the key to reducing the chances for cracks.
Pith In
While the pith can be left in a green wood bowl turning, it really needs to be carefully handled. I would suggest positioning the pith, if left in the bowl, down the side of a bowl and not along the rim edge.
The most important aspect of green wood bowl turning with or without the pith is to make the bowl walls even throughout. It doesn’t necessarily matter what the wall thickness is, just that it is even throughout from rim to bowl bottom.
Shape Shifting
As the kitchen sponge image above illustrates, the shape of a green wood bowl turning will change as well. It is merely the nature of working with green wood.
When you make a green wood bowl, it is important to realize that changes to the bowl shape will occur as the bowl’s moisture content moves towards equilibrium. Do not have unrealistic expectations of a perfectly round-rimmed final bowl. That is not what happens when turning green wood bowls.
A simple round turned traditional bowl will most likely elongate a bit and distort as it drys. Usually, the rim will have elevated areas that form near the pith on each side of the bowl rim. This is the natural movement of the wood grain as it drys.
Turning green wood bowls relatively thin can cause warps, waves and dancing wood during and after the drying process. I’ve seen some that have very little roundness to them once their moisture equalizes. It’s hard to picture they were ever attached to a lathe at one point.
This is all part of the fun of green wood bowl turning. However, if you’d like to use green wood to make more precise predictable final forms, be sure to read the green wood twice turned section below.
Species Specific
To add to the unpredictability of turning green wood bowls, each tree species behaves differently than one another.
For instance, cherry can be super finicky and is ready to crack if you look at it wrong. While hickory is usually rock hardwood that can be shelved for years and turned crack free usually.
Each species of tree grows, forms, and develops differently. For example, the Eucalyptus is said to pull microscopic grains of soil with silica into its cells as it grows. This can potentially be hard on steel tools, but how does that affect the wood’s structure? Each wood species is different and will behave differently.
Turning Green Wood Bowls – 4 Things To Consider
Green wood is genuinely satisfying to work with. Long curling shavings glisten with moisture and fall to the floor leaving little or no dust. At times the wood seems to cut like a bar of soap, effortless and smooth.
It is important to remember the characteristics of this wet wood. The green wood can be spongy, and there are particular things to consider while turning.
- For instance, the tenon or mortise on the foot of a bowl will have a bit of give so its essential to size and shape the tenon or mortise carefully to maintain the best grip.
- If a faceplate is being used, it’s not a bad idea to use a bit longer screws to create a better grip as these too can work their way out of the soft, moist wood.
- Because the wood is sensitive to quick changes in moisture content, it’s essential to completely turn the piece you’re working on within a relatively short period of time. In other words, if the outside of the bowl is turned and you decide to wait until tomorrow to turn the inside, you may return to find all kinds of nasty cracks and checks especially along the end grain of the bowl.
- Many people think you can not sand green wood. I’ve found this not to be true. Now, if the surface is dripping with water, yes it will be difficult because sanding will mostly make a slurry that will plug up the sandpaper. If the wood is really wet, I’ve found waiting ten minutes or so allows the surface to dry just enough to let the sandpaper to do its job. I also use mesh sanding disks that can be cleaned quickly and don’t allow the debris to build up as much as traditional sandpaper.
Turning Green Wood Bowls Experiment
If you are like me and you have many different growing timber species available in your local area, consider conducting this experiment the next time you land a pile of turnable wood. Take an available log of one species, ideally one that is typical and average from a pile of similar logs, and make several bowl blanks.
On the lathe, turn sample bowls to determine how the green wood will behave. Turn a thin walled bowl, a medium thick walled bowl, and a thicker bowl. Let the bowls air dry or place them in paper bags with fresh shavings.
What happened to each of the different bowls? Did cracks form, and if so where were the cracks? Did the wood move, warp, wave, or deform, and which thickness bowl moved the most?
You may be surprised to discover, that these results are most likely typical for that species of tree and if you did your test again on an entirely different tree of the same species, you’d probably see similar results.
Turning Green Wood Bowls Thin
Turning green wood bowls thin walled can be a lot of fun. Not only does the wet wood cut smooth, crisp, and relatively dust free, light easily passes through the thin moisture wood fibers.
Place a light source behind the bowl once the wall thickness has been reduced and you can use the resulting brightness as your wall thickness gauge. If the light shining through the bowl wall becomes brighter, the wall is getting thinner. Ideally, a continuously even lit appearance down the bowl wall is the goal.
Also, when turning very thin-walled green wood bowls, the amount of area to hold moisture has dramatically been reduced. This means the green wood will dry very fast, so you need to work rapidly. Spraying a mist of water from a water bottle sprayer on the wood at regular intervals will prevent the wood from drying prematurely as you work.
Turning Green Wood Bowls Medium Thick
The green wood medium walled bowl is an excellent test for a tree species. Turning green wood bowls about a half-inch to three-quarters of an inch thick are usually pretty stable. Again, even wall thickness is the key to preventing too many surprises and nasty cracks.
Medium thick bowl walls typically have good structural support for the bowl’s shape, and they release moisture content slowly over a more extended period of time, which eases the bowl into it’s equalized form more gracefully.
However, again, it’s all about the species and conditions. Where medium thick walled green bowls are fantastic for one species, they may not work at all for another tree species. The importance of experimentation can’t be underestimated.
Green Wood Twice Turned
Turning green wood bowls twice always reminds me of twice baked potatoes. And the process is very similar in a few ways.
The principal behind twice turning green wood is first to create a rough bowl shape that can dry and reach equilibrium before being turned a second time to the final finished shape.
We know that green wood is going to move, shift, and reshape as it dries. The first stage of twice turnings accounts for this by removing the mass of the wood and creating even walls to allow even moisture to escape.
Then the second stage of the twice turned wood bowl takes advantage of the fact the wood is now much more stable to make a more dependable shaped final bowl.
How to Twice Turn A Green Wood Bowl
To size the first rough turning for a twice turned green wood bowl, the rough wall thickness is critical. The rule of thumb is the wall thickness needs to be about ten percent of the overall bowl diameter. So a 10” wide bowl should have a rough wall about 1” thick.
Why such a thick wall? As the bowl deforms in the drying process, the pith ends of the roughed bowl will stretch and elongate typically. As this happens, an oval is formed. Having the thick walls will allow enough material to second turn a true round exterior circle and then a final inner circle.
If the walls of the twice turned roughed bowl are too thin, the second turning will cut through the more extended areas and destroy the bowl. There just would not be enough material to reveal a final round shaped bowl.
On the other hand, if the bowl is made too thick, it will take too long to dry, and they will merely be excess material to turn away needlessly.
Turning Green Wood Bowl Benefits
You may be thinking, with all these factors and nuances to consider, why even bother with turning green wood? After all, purchasing a nice clean, dry bowl blank is nearly effortless.
This is true, but there are many drawbacks to buying prepared dry bowl blanks, including excess dust, predetermined wood cuts, and the expense.
Using green wood for wood turned bowls has so many advantages.
First of all, green wood is everywhere around and usually free for the taking. Recycling a fallen tree is a whole nature-soaked interactive process with our environment.
Creating green wood bowl blanks is a gratifying and satisfying process. Not only does it help someone clear what they may consider waste debris, but it also yields lasting heirlooms of beauty when turned into wood bowls.
Green wood is usually free. How many things in life are reliably free and plentiful? Not too many. With a little exploring, there are numerous ways to acquire free wood to turn bowls.
Green wood, in most cases, was headed for a different demise of rot, compost, mulch, or worse yet, fire. Think of saving and using green wood as a rescue and recovery mission. This would be funny if it weren’t true. The number of beautiful wood species trees that go to waste is astonishing.
Turning green wood is a fantastic experience on the lathe. Many species of timber, in green form, turn buttery smooth and surrender gracefully to the bowl gouge.
Wet green wood turns more efficiently and cleaner than dry wood. Free flying dust is reduced making the air a bit safer to breathe. Shavings from green wood come off large and curly producing little or no dust. The moisture in the wood has the added benefit of cooling the tool’s cutting edge helping it stay sharp longer.
My favorite thing about beautiful free green wood is you never know where it will come from next and what species it might be. It could be a storm that makes literal tons available, or a friend calling to let you know about a recently removed specimen.
Heck, even driving becomes more interesting when you’re on the lookout for new turning material. I’ve stopped randomly many times to chuck logs from ditches into my trunk.
When collecting, cutting green wood bowl blanks, and turning green wood, we the creators of the final wood turned bowls, get to decide where we would like to cut the wood and in what direction and to what final size. We are engaged in the entire process from the source to the final turned piece. This is not possible when purchasing dried bowl blanks, as someone else has already made all those decisions long ago.
Turning Green Wood Bowls – Conclusion
Turning green wood is a hands-on process that places the woodturner in charge and at the helm from start to finish.
Massive amounts of experiential knowledge are gained when turning green wood bowls. Turning skills specific to each tree species become engrained into our hand, eye, and tool coordination.
In many ways, we truly honor the very nature of the tree as we gracefully and elegantly lift it from the process of decay and set it on the stage of appreciation, for generations to come.
Check out these other great green wood articles:
• DRYING GREEN WOOD BOWLS – 6 METHODS FOR SUCCESS
• GREEN WOOD BOWL BLANK MAKING PROCESS
• SPALTING AND SPALTED WOOD BOWLS
• HOW TO SHARPEN A CHAINSAW – ILLUSTRATED GUIDE
• BOWL TURNING GRAIN ORIENTATION – WOOD BLANK DIRECTION
Happy Turning,
Kent
24 Responses
Can you please send me a link for your e-book?
Greg,
Sure, check them out here http://www.TurnAWoodBowl.com/shop
Thank you, and Happy Turning!
Hi Kent
big fan of your you tube channel. i have a question about turning green wood. the rule of thumb for turning a green bowl is the wall thickness should be 10% of the overall diameter.
is there rule of thumb for turning triwinged bowls that are green? there really is not a consistent diameter. the tips of the wings will dry much faster than the area near the tenon.
any guidance would be appreciated
Vincent.
Good question. You will still need to rough a blank that is about 10% wall thickness to full diameter. Although, I’d make those walls a bit thicker for a 3-sided bowl, perhaps 20% of diameter.
Happy Turning!
Kent
I am turning chess pieces from cuttings from our peach trees. Green for sure. They turn beautifully, and I have had the pieces stacked in a dry basement for about a month. Results have been good but probably 15% are cracked. I am thinking of roughing out the pieces and letting them sit for a few days, then going back to finish us. Maybe the bark is keeping too much moisture in.
Todd,
I don’t do a lot of spindle work, but in my experience, you do want to rough turn them larger than you will need. This opens the surface area and allows for drying. Once they are dry or equalized, then you can final turn them.
All the best to you and Happy Turning!
Kent
This article has been more helpful to me a beginner than any I have read, and I have read many. Thanks for sharing your know.
Thank you David. If you liked this, you’ll probably love the course. Check it out http://www.TurnAWoodBowl.com/green All the best to you and Happy Turning!
A lot of good information here. I have been turning for about twenty years off an on but just recently got into green turning. I tried the denatured alcohol trick ( put in 5 gallon bucket and cover for about three days, take out and put in paper sack with shaving) and it works as far as keeping checks and cracks down but leaves wood very rough and rough grain that I can’t seem to turn out or sand out. Have you ever run across something like this? It’s on black locust. It has a very pretty grain.
Thanks for sharing. I have not tried this technique, but it kinda makes sense. If those fibers are soaked they have a tendency to raise up. Every tree species will react differently, but it sounds like locust fibers rise up in this soak. Good to know.
I tried something today. Sanded with 40 grit and used a bull nose scraper with no success. I thought what can I fill with, so I had some sanding dust on shop floor and mixed with titebond glue and spread over the whole bowl. I’m letting dry overnight. Will put back on lathe and sand and see if it comes out smooth. I’ll let you know how it does.
Richard,
That’s an interesting approach. Once you are comfortable making clean bowl gouge cuts, depending on the wood, you might be able to start sanding with 180 or 240 grit paper. If you’d like to learn all about the techniques needed for this, see this info turnawoodbowl.com/turn I think you will see a huge difference.
Happy Turning,
Kent
I put a glue sawdust mix and let dry for 24 hrs. Put back on the lathe and sanded with 40 grit and used a heavy nose scraper. Sanded again with 60 up to 220. It finally is smooth.
Sounds great!
Hi Kent,
First, thank you so much for putting all this effort in to writing these articles. I’m a new wood turner as of late March 2020. I’ve watched videos of wood turning for over a year, and it suddenly hit me this year…I could just do it myself, too! So I did.
I’ve had a heck of a time with cracking wood, though. Almost all of the pieces I turn crack. Some very beautiful pieces of wood, one more recently a truly beautiful piece of Rainbow Cottonwood, have become totally ruined due to cracking. I can’t seem to get away from it, no matter what I do. Maybe you can offer some advice.
I live in Colorado. It is ARID here! I mean, it is really dry most of the time. Maybe not quite “desert” dry, but it seems to be getting pretty close. I often enough measure 16% or lower humidity, and it is rarely much higher than that unless it is literally raining cats and dogs outside, which it doesn’t seem to do much lately (2018 and 2019 were very wet, 2020 is bone dry). So, very dry here.
So dry, in fact, that I can’t even seem to get a rough turn of any green piece of wood over 15% MC (based on a moisture meter) without cracking. Usually, my pieces will start cracking (not just checking, but cracking) shortly after I’ve completely removed the wax coating. If they don’t start cracking immediately (i.e. if MC is upwards of 35%, it might take longer before enough moisture is lost), then they will usually have cracks before I can even finish the outside, let alone get a rough turn on the inside so I can then let the rough turned, 1″ thick bowl dry before I turn it a second time.
I was so enthusiastic earlier this year when I got going, that I was buying wood left and right. I’ve got a pretty hefty pile of wood, most of it green, a majority of it with MCs around 20-35%, and most of it over 15% MC. I’ve now come to the conclusion that all this wood, hundreds (thousands?) of dollars of wood is just going to go to waste if I cannot figure out how to turn it, without it cracking like hell was breaking through the crust of the Earth.
I’ve switched to buying only kiln dried wood, unless its just a particularly special piece. The kiln dried wood does not have this cracking-while-turning problem, obviously, but a lot of woods just don’t seem to have the same beauty if they are KD as when they are green (walnut, rainbow cottonwood, others). There are also some woods you just cannot seem to find kiln dried at all, they only seem to be sold green. Not to mention all the other benefits you mentioned in your article about green wood.
I also find a certain enjoyment turning green wood. KD is fine, and not having the cracking is great, but there is something about green wood. The way it cuts, the clean, curly shavings and chips you get off a green blank, the significantly lower amount of dust (for me, this is a big bonus as I seem to be very allergic to wood dust!), and finally the richness of the colors in the end (especially walnut and red gum…both of those seem to maintain a much more vibrant and diverse color, than KD…in fact, I’m not even sure I’ve ever found KD gum, but KD walnut seems to just be “Brown” where as green walnut…oh, it can have so many colors!)
So my question is…is there anything I can do, to be able to turn a green piece of wood, in a very arid climate, and avoid having every piece (regardless of species, it seems) crack DURING turning. I’d like at least to have a chance to rough turn, then slow down the drying process, or use maybe a fridge kiln, etc. and at least try to avoid cracking. 😉
I’ve racked my brain, and short of trying to install a hefty humidifier or swamp cooler or something (which just wouldn’t be an option in the winter here in Colorado anyway), I’ve been unable to come up with a solution. Short, at least, of just letting the dozens of wood blanks I’ve acquired (including some fairly large 6x6x12 green vase blanks) just sit and dry in their wax for the next 2-3 years, that is.
Thank you so much!
Jon,
I hear your frustration. First off, I’d recommend going smaller. Try to get locally harvested wood but in smaller quantities. You will need to immediately turn ALL of the wood you get because of the dryness you describe. So work with a few logs at a time.
Cut the logs about two times longer than their diameter. Accept that the ends will crack, but with the extra wood, you can trim that off when you are ready to turn. As soon as the logs are split and ready to be shaped into bowl blanks, you have to also be ready to turn them down to final size (or twice-turned roughed size). I’m talking within minutes.
If you cut more than one bowl blank at a time, I’d soak an old towel and wrap the bowl blank sopping wet and then wrap that with wide plastic wrap. Even if only for a short time. On the lathe, you’ll need to have a water mister handy and spray the blank often on both sides. If you need to take even a brief break, place a plastic bag tight around the blank before stepping away. Turn the complete bowl at one time. You can not turn the outside and then wait to turn the inside later, it will crack in your environment.
Your goal is to keep as much moisture in the wood as possible. You don’t have to worry about a drier of any sort, the air is doing that automatically. As soon as a blank is turned to very even wall thickness throughout, then mist it again and place it in a brown paper bag. If the shavings from that turning are even a little moist, use them to line the bag and cover the bowl. This will help retain moisture in the bowl. Roll the top of the bag shut. Check the bag every day or two and replace it with a fresh bag if moisture is still present.
Put the bags in a cool dark space with very little air movement. A crawl space is ideal. If you’re rough turning them, to be turned a second time after drying, use Anchor Seal and coat the end-grain areas only both inside and out before placing them in the brown bag.
These steps should render better results, but you still might get some cracking. Remember it also has a lot to do with the tree species as well. I haven’t turned much cottonwood, but I know it is prone to splitting cracks.
Work in small batches and experiment until you find a technique and type of wood that works best for you. Don’t get large quantities of wood, because you will probably continue to see a lot of waste. Think of the bowl blanks you create as grocery store produce. You need to take care of them and store them according to their needs, or they will spoil.
All the best to you and Happy Turning,
Kent
Hi Kent,
Thank you for taking the time to write such a thorough reply. I have considered misting the blanks. I actually even considered using some trip system tubing and misting sprayers, along with a basic low volume pump, to set up an automatic powered mister to just keep the blanks wet while I turn, as some times it seems even stopping to find the spray bottle and mist them allows enough time for the wood to crack (although, I think that was the Cottonwood, so maybe it was the species being problematic as well in that case.)
I’ve rounded several other green square waxed blanks I purchased. They had 20-30% moisture content according to my meter. I removed the was from the top and bottom and rounded them. The moment they started to crack, I anchor sealed the end grains, but left the rest of the wood unsealed. The cracking stopped immediately…and, the blanks are clearly losing moisture. Every time I check them (and they are just air drying, no paper bags for these yet as they haven’t been hollowed yet), they are lighter than before. Much lighter now, as I rounded these a couple months ago. So I may also just try rounding some of the green blanks I have, seal the end grains, and let them air dry for a while, and see how that goes as well.
I am curious…have you ever tried kiln drying your own wood? Worthwhile effort to say pick up an old free fridge and convert one into a kiln? Or just a waste of time? I do wonder if the ability to control temp and humidity might help here in my dry state….
Jon,
Thanks for writing back.
Quick note–if you are rounding just the bowl’s exterior blanks and not coring out the center, you will probably have issues. I’m not sure if that’s what you’re doing or not. If you are going to twice-turn, you will want to turn a thick-walled complete bowl essentially (with the tenon still attached). The only reason I mention this is because if the center is solid and not removed at all, the moisture and tension is concentrated in that core and will easily crack end-grain and much more. You may be coring this properly already. I’m not sure.
As for a kiln, I do have an insulated box with a light bulb. Believe it or not, that’s all you need to dry the bowls. A full kiln that would apply measurable heat is too much and will most likely make many cracked bowls. I’m converting an old upright freezer soon and it will be featured in an article and a video. Stay tuned.
Happy Turning,
Kent
I have actually done both. Just rounded and waxed the end grains again to let the remainder dry slowly over time, as well as rounded and hollowed, so the walls are around 1″ thick. I seem to have problems either way. I do understand what you are saying about getting that wet core out though…the wood wants to dry around the core, and will split then contract radially… Note that, while I have picked up some logs from recently cut down trees, most of my blanks I’ve bought from one store or another (green valley, turning blanks.net, cook woods, etc.) I bought a lot of green or semi-green blanks earlier in the year, before I had the understanding about wood and drying that I have now…so I’ve got quite a pile of green wood that…at the moment, I feel I cannot turn, and will probably sit and dry for a year or two at least.
The challenge I’ve run into, regardless of what I do…is that the FIRST time on the lathe, the wood cracks before I’m even done rounding, let alone before I get a chance to hollow. Now, I do think there is species variability here…I’ve been at this for about 8 months, turned a couple dozen or so bowls and boxes, so I don’t have a huge amount of experience with wood varieties yet.
Some woods have been horrible…like the cottonwood, within minutes of starting to round a square blank, and this was after it sat and dried for around 6 months (and was already air drying before I bought it), it had tons of checking and some of the checks were already splitting into cracks. I decided to finish rounding it, and by the time I was done, it was full of cracks along the end grains and was basically useless. I ended up finishing the bowl, as the wood was actually BEAUTIFUL, but it was ruined and unsellable within 10 minutes or so of first putting it on the lathe and starting to round.
I’ve had the same problem with most of the other pieces I’ve turned, at least if they were green wood (in various stages of drying…some very green, some months or nearly a year into drying in full wax). Moisture contents range from 15-35%, and it doesn’t seem to matter what % it has, if its still green, it will usually crack before I even get a chance to flip the bowl and hollow it out.
In some cases, I do get to hollowing, but usually, if the wood is still green or greenish, buy the time I finish hollowing down to a 1″ wall thickness so I can then let it dry…usually I’ve got cracks inside and/or outside already, so the piece is basically already ruined. I’ve tried twice turning, oh…a number of times now, and so far I haven’t quite been able to get things turned fast enough that the bowl is still in good shape by the time I get it into a bag with shavings (or in my case, I’ve had a bucket with shavings, and a perforated lid…we don’t have any paper bags and most of the grocery stores we shop in either have plastic, or reusable bags :P)
Needless to say, its been a great source of frustration. I’ve started turning only kiln dried blanks lately…but, choices are limited, the amount of dust goes through the roof, and depending on the wood it can be harder to turn than when green. I’m not sure if this is an environmental issue, though…as in “its just the dry Colorado air”, or if I’m actually doing something wrong when I turn (too much friction and heat?) I suspect it is probably a combination of both. Colorado is extremely arid, so I’m sure the dry air is part of the problem…but I can’t shake the feeling I’m doing something wrong as well.
Anyway…I look forward to your upcoming fridge kiln video! I’ve watched a couple from other turners, and they have me intrigued. They seem pretty simple, basically a light bulb, a fan, some controllable venting… I do value the knowledge you in particular bring to the table though, Kent, so I look forward to your insights. I’m a software engineer, and am very attentive to the details…I appreciate the depth you go into in both your articles and your videos! 🙂 They have been extremely edifying. Thank you for it all!
Jon,
Thanks for writing. I feel your frustration.
I suggest turning only small batches of wood at a time. Turn one blank from start to finish and do so in under two hours tops.
It sounds like you don’t have any need for a bowl blank drier. Your environment is your dryer. What you need to focus on is finding a tree species that is a bit more forgiving and will allow you to turn it before cracking.
While you’re on the lathe mist the wood surface thoroughly with a water mister. If you take even a 5-minute break to go to the bathroom, cover the bowl blank on the lathe with a plastic bag. The end grains of the blank are drying so fast they are forced to crack. Keep the end grain wet at all times.
As soon as you finish turning the piece, apply an oil or shellac finish to further hold moisture and slow the drying process. You can even just apply finish to the end grain if you’d like, but this might cause a color difference overall.
Treat this time as an experiment. Work with different woods. I think you’ll discover cottonwood is not the best for any woodturning. Although available, it’s not a very good quality and will crack like crazy. Have you turned any aspen yet?
In your dry environment, think of the bowl blank as a special needs ICU patient that will die without moisture. Kepp it wet and cover it always until you’ve finished turning each piece.
All the best to you and I hope you resolve this issue!
Happy Turning,
Kent
How do you deal with holding the bowl after drying and warping?
Dan,
Great question. I like to use a jam chuck to re-true the tenon. You can use a jam chuck shaped to fit in the interior of the bowl, or a flat padded jam chuck. Check out this video to see what I’m talking about. https://youtu.be/2qor9wes5zk
Happy Turning,
Kent
I like it, I learned a lot, I am a Rookie at Turning but love it!
Charles,
Thanks for writing. Keep on turning!
Happy Turning,
Kent