I started with a live Sweet Gum tree from my neighbors yard this spring. I cut it into logs and they sat for a couple months before I got around to roughing the blanks out, which was about three months ago. I coated the blanks in Anchorseal and put them up on a shelf in my shop. My shop is air conditioned, but not refrigerated, temps stay mid/upper 70s and humidity usually low 50s. I looked at them yesterday, they have obviously dried considerably. Some of them are egg shaped to where I'm not sure there is a bowl left in them. on the positive side, not a crack or split in any of them. Other than experimentation, is there a way to judge when these might be ready for a finish turning? I would guess that it's probably too early yet, but this is new to me. There is another recently felled tree next door that I am planning on cutting up soon and am considering flat round blanks instead of hollowed bowl blanks, this is obviously going to extend the drying time, but how much? An alternative to drying them in the shop would be to store them in my attic, where it is much warmer and also more humid (S Alabama). Good idea? Bad? Try it and see? I understand that there are no precise answers to these questions, just trying to get a feel for where I am.
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Drying time for rough turned blanks.
- Thread starter David Martin
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You can easily determine how dry your wood will get in each location with a thermometer and hydrometer.
Simple wood science the wood MC(moisture content) will reach equilibrium with its environment.
My drying room had a dehumidifier that keeps the humidity at 50% - highlighted area in chart
My pieces will dry to about 9%. They will never get any dryer in that environment
This is a US Forestry service chart
I use a two pin moisture meter on the tenons. When it is around 9% I consider the bowl dry. Not super accurate since it doesn’t measure the bowl walls - it works for me and isn’t much work.
A more accurate method is to weigh the bowls periodically (once a month or every 2 weeks). When they stop loosing weight they have reached equilibrium in that environment - assuming the environment has not changed.
When I used to use anchor seal, bowls took 10-12 months to dry
I now use paper bags and bowls dry in 7-10 months
A bowl with more than 10% MC is likely to warp when brought into a home with a stable environment or a low winter humidity.
Simple wood science the wood MC(moisture content) will reach equilibrium with its environment.
My drying room had a dehumidifier that keeps the humidity at 50% - highlighted area in chart
My pieces will dry to about 9%. They will never get any dryer in that environment
This is a US Forestry service chart
I use a two pin moisture meter on the tenons. When it is around 9% I consider the bowl dry. Not super accurate since it doesn’t measure the bowl walls - it works for me and isn’t much work.
A more accurate method is to weigh the bowls periodically (once a month or every 2 weeks). When they stop loosing weight they have reached equilibrium in that environment - assuming the environment has not changed.
When I used to use anchor seal, bowls took 10-12 months to dry
I now use paper bags and bowls dry in 7-10 months
A bowl with more than 10% MC is likely to warp when brought into a home with a stable environment or a low winter humidity.
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I’m surprised the Sweetgum is moving that much, but not surprised about the lack of cracks. Hard to crack that stuff. It will get small tears where the stresses are high, like next to figuring.
Three months isn’t nearly enough time. I like completely coating in anchorseal because it’s slow. Slower drying equals stronger wood.
A two pin moisture meter will give you a good idea of where you’re at. Although you will be testing the wood at the surface, not at the center, the slower drying, the partial seal at the surface gives a moisture reading that will be close to uniform.
10 months minimum, longer if you’ve got the time
Three months isn’t nearly enough time. I like completely coating in anchorseal because it’s slow. Slower drying equals stronger wood.
A two pin moisture meter will give you a good idea of where you’re at. Although you will be testing the wood at the surface, not at the center, the slower drying, the partial seal at the surface gives a moisture reading that will be close to uniform.
10 months minimum, longer if you’ve got the time
Get a kitchen scale, weight each, put some painters tape on each and write the wt & date on it. If they don’t loose any wt for a week, they are dry (for the conditions stored in). Dont recommend the attic, when its warm anyway - too hot.
I use paper bags(double bag) less mess than a sealer. Weight initially, then maybe a month later, then every week or 2. After doing this for a while, you can judge how wet the blank is (or use a meter) and approximate dry time - dont have to weight as often. I keep mine in the house on wire shelving.
I use paper bags(double bag) less mess than a sealer. Weight initially, then maybe a month later, then every week or 2. After doing this for a while, you can judge how wet the blank is (or use a meter) and approximate dry time - dont have to weight as often. I keep mine in the house on wire shelving.
I can sometimes finish turn soft maple after six months. I try to leave everything on the drying shelf for a year. Never had a problem with anything after a year.
I have access to a moisture meter but I have stopped using it simply because it only reads a surface value, which doesn't give you any useful or reliable information. I don't use Anchor Seal on once turned pieces because there is no way to get it off short of turning it off so I have gone the brown paper bag route and found that the bags work just as good on rough turned pieces.
To determine when a piece has reached equilibrium I start by recording the weight when it comes off the lathe and then put it into a bag. Initially I will weigh and record once a day and then start spreading out the weigh intervals and finally when no change occurs over a reasonable time I know when it has reached equilibrium. The area that I live in has high humidity in the summer with an occasional reading of 100 degrees F and low humidity in the heated areas in winter with an occasional outside reading as low as -40 degrees C/F and I have seen slight increases in weight in the transition period.
To determine when a piece has reached equilibrium I start by recording the weight when it comes off the lathe and then put it into a bag. Initially I will weigh and record once a day and then start spreading out the weigh intervals and finally when no change occurs over a reasonable time I know when it has reached equilibrium. The area that I live in has high humidity in the summer with an occasional reading of 100 degrees F and low humidity in the heated areas in winter with an occasional outside reading as low as -40 degrees C/F and I have seen slight increases in weight in the transition period.
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Ditto- What Don said above is exactly what I would have wrote too. (brown bag em and weigh em, basically same climate here in P.A.)
I agree with Doug. I do for bowl put shavings in a bag and open it daily to release moisture. Weigh every 2-3 days. Remove shavings after two weeks and place back in bag or in Kiln. Continue to weigh till no change with taking off the bag if loss below 5 GM.
What I have found is depending on the species you're trying to season it all varies somewhat. Now most your species I dont see down here so my comment will be general I guess. With soft and stable species I rough turn and do half a dozen or so paint the outside with BLO and put the lot in a card board box and keep the lid closed. Checking them every week or so with a moisture meter, generally 6-8 weeks and they are ready to go. OK I place them on the floor in coolest spot in the shop out of the way from sunlight draughts etc. Hardwood is a different all together, its a matter of time as the harder the wood the more challenging is the drying .
I tried the brown paper bag with shavings and lost around 25% to cracks. Now I seal with green wood sealer and put on the shelf. I have never lost one that way, yet.
Dave Landers
Beta Tester
Every one of us is in a different climate/environment for drying bowls. It's not just the area where you live, but the micro-climate in your shop, shed, garage, etc where you store your drying bowls. Temperature, humidity, sunlight, air movement, etc. Different wood species (or different trees) also dry differently.
So the best thing is to keep trying things till you find something that works. All the good advice you get about what works for other turners just amounts to "things for you to try". When you find something that works "for you" - stick with it (until it doesn't work anymore because something changed).
I just moved across town and am having a new shop built - so I get to start this whole process all over again in the new place. My previous methods will probably be a pretty good start, but I will probably have to adjust.
As to when a bowl is dry - the "weigh it till it doesn't change" approach is pretty good. Another approach - if you have a group of bowls from the same tree, same rough-out session - just pick one and re-turn it and see what happens.
After you do that a while, you may stop weighing (or otherwise testing) and just know that it takes about "X" months "for you".
So the best thing is to keep trying things till you find something that works. All the good advice you get about what works for other turners just amounts to "things for you to try". When you find something that works "for you" - stick with it (until it doesn't work anymore because something changed).
I just moved across town and am having a new shop built - so I get to start this whole process all over again in the new place. My previous methods will probably be a pretty good start, but I will probably have to adjust.
As to when a bowl is dry - the "weigh it till it doesn't change" approach is pretty good. Another approach - if you have a group of bowls from the same tree, same rough-out session - just pick one and re-turn it and see what happens.
After you do that a while, you may stop weighing (or otherwise testing) and just know that it takes about "X" months "for you".
I do mostly twice turned. I leave about 10% additional wall and bottom thickness for the second turning. When the green turning is finished, I coat everything with Anchorseal2 and then put it into my homemade kiln which remains at a constant 100*. I weigh them once a week, measuring weight loss in grams, and when they quit losing weight, I let the acclimate for a week, then finish turn them. I usually get a bowl out in about 6 weeks, but it varies a lot with species. Some wood, like Walnut, are slow to give up their moisture, but Cedar dries quickly. I have very little cracking, and have found that wood movement depends somewhat on species and grain structure. Persimmon, for example practically folds itself in two, but most of the Maple I turn and Bradford Pear seem to be pretty stable.
odie
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As can be seen in this thread, there are a variety of opinions on determining when stabilization occurs.
For my own twice turned bowls, I use full coverage of anchorseal (same-same "green wood sealer") on rough turned bowls.....and a minimum of three months of unchanged weights before I'll return it to the lathe for final turning. During the winter months, I may opt for longer, because the moisture loss is slower in winter months. Since I have a minimum of 50+ bowls in the seasoning process at any one time, I seldom need to push the envelope and turn a bowl that I'm unsure of.
I do use a moisture meter on the initial block of wood, and don't use it after that. The useful information it gives, relates to what can be expected in the seasoning time it will take. This information is to be combined with species of wood, plus size and thickness of the roughed bowl before any calculations can be made.
-o-
For my own twice turned bowls, I use full coverage of anchorseal (same-same "green wood sealer") on rough turned bowls.....and a minimum of three months of unchanged weights before I'll return it to the lathe for final turning. During the winter months, I may opt for longer, because the moisture loss is slower in winter months. Since I have a minimum of 50+ bowls in the seasoning process at any one time, I seldom need to push the envelope and turn a bowl that I'm unsure of.
I do use a moisture meter on the initial block of wood, and don't use it after that. The useful information it gives, relates to what can be expected in the seasoning time it will take. This information is to be combined with species of wood, plus size and thickness of the roughed bowl before any calculations can be made.
Rusty has a pretty good method, if a scale isn't used. One year covers a lot of domestic woods, but may fall short on some exotic, or very dense woods.
My experience is very nearly the same as Rusty's here. I've used paper bags and wood chips, and I've also had cracking issues with some woods. I've found that anchorseal has been my best method for slowing down the drying process in the full spectrum of all possible wood species, shapes and sizes. A basic rule of thumb would be, the slower the drying process, the better the results will be....the less cracking issues you'll have.....time, is your friend.
This is good advice from Dave ^^^^^. Bottom line is what works well for me, may not be what works best for you. You have to "walk the walk" in order to find that "best" method for your own particular environment, and application.
-o-
I like the lignomat that reads 3/4" deep. I've never had a problem with the blank being dry when it reads 10%. More accurate than the pins
Thats why I double bag them (no shavings). Whether a bag or something put on to seal, the intent is to slow evaporation. It depends a great deal on the climate the items are kept in - the more consistent the climate the more consistent the results. I rarely see cracks anymore. Early on a lot of the cracks were do to my inexperience of cutting blanks - didnt understand sometimes you just have to shrink a blank/roughout to prevent cracks.
I read the different answers and saw the problems some have with using the brown paper bag to dry the rough turned wood, the problem people get is not the brown paper bag but the addition of chips/shavings in the bag.
By adding shavings you get uneven drying, as where the wood sits against the shavings there is little to no drying, while at other parts where the wood sits free from the shavings it will dry, so you create uneven drying and induce stress in the wood that then can have the wood split.
As I have been telling to use the brown paper bag for years and years, at first it was not believed, as everyone was trying the dishwashing soap that was claimed to dry it fast with no cracks and no distortion, (a lot of BS), than it was soaking in alcohol for those same outcomes, again BS.
Using a way to slow down rather than trying to dry faster is still the proven way to dry the wood and giving it time to change it's shape slowly that will dry without splitting, and yes some people have different indoor conditions, and that will affect the drying, air over and heat will increase the speed of the bag drying, and that can be too fast.
As I have said over and over again, put the turning in a brown paper bag and set it at a cool place with no draft or heating and the piece will dry without checks or splits (Do start with wood that has no splits before you start)
By adding shavings you get uneven drying, as where the wood sits against the shavings there is little to no drying, while at other parts where the wood sits free from the shavings it will dry, so you create uneven drying and induce stress in the wood that then can have the wood split.
As I have been telling to use the brown paper bag for years and years, at first it was not believed, as everyone was trying the dishwashing soap that was claimed to dry it fast with no cracks and no distortion, (a lot of BS), than it was soaking in alcohol for those same outcomes, again BS.
Using a way to slow down rather than trying to dry faster is still the proven way to dry the wood and giving it time to change it's shape slowly that will dry without splitting, and yes some people have different indoor conditions, and that will affect the drying, air over and heat will increase the speed of the bag drying, and that can be too fast.
As I have said over and over again, put the turning in a brown paper bag and set it at a cool place with no draft or heating and the piece will dry without checks or splits (Do start with wood that has no splits before you start)
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"...There is another recently felled tree next door that I am planning on cutting up soon and am considering flat round blanks instead of hollowed bowl blanks, this is obviously going to extend the drying time, but how much? ..."
^^('couldn't get Quote function to cooperate during an Edit.)^^
Drying rough-turned bowls is much better than trying to dry un-turned blanks.
I typically double-bag with openings completely sealed tight with tape - 'works well for me.
Tim
^^('couldn't get Quote function to cooperate during an Edit.)^^
Drying rough-turned bowls is much better than trying to dry un-turned blanks.
I typically double-bag with openings completely sealed tight with tape - 'works well for me.
Tim
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I can't think of anything to add to this since all the BS has been explained by Leo just read it over several times.
The LDD (liquid dishwashing detergent) soak only makes difficult woods more easy to sand with less clogging. It was developed by Ron Kent in Hawai'i for dealing with the Norfolk Island pine and other similar woods. I tried the DNA and LDD on a couple of pieces, and there was no difference in drying speed and/or cracking. The DNA soaked piece was more difficult to sand out, much more so when compared to the LDD method.
If I was to twice turn my bowls, I would round over the edges of the rim, seal with wood glue, and wrap the rim with the stretch film. Some woods the 10% thickness method works. Some woods it doesn't, and Pacific Madrone is one of those. Madrone has an extremely high water content, some thing like 75%. Best way to deal with it if you twice turn is to boil it. I believe sycamore holds almost as much water ad Madrone does. Not sure about the sweet gum, but especially with spring harvested wood, it will have a higher water content. I have noticed with my madrone, that I get less cracking with spring harvested trees where the water is high, and more cracking with mid summer/late summer trees. Same for trees that have sat on the ground for a while.
robo hippy
If I was to twice turn my bowls, I would round over the edges of the rim, seal with wood glue, and wrap the rim with the stretch film. Some woods the 10% thickness method works. Some woods it doesn't, and Pacific Madrone is one of those. Madrone has an extremely high water content, some thing like 75%. Best way to deal with it if you twice turn is to boil it. I believe sycamore holds almost as much water ad Madrone does. Not sure about the sweet gum, but especially with spring harvested wood, it will have a higher water content. I have noticed with my madrone, that I get less cracking with spring harvested trees where the water is high, and more cracking with mid summer/late summer trees. Same for trees that have sat on the ground for a while.
robo hippy
In my opinion, DO NOT PUT THE BOWL BLANKS IN THE ATTIC! Your Attic overheats in the summer (especially in AL) and is a guaranteed way to promote cracks. I know because I did this when I was a new turner. I ruined a bunch of nice blanks. Currently, I cut round flat bowl blanks, Anchorseal the end grain and wrap them with Clingwrap. I do get some mold -not really an issue. Blanks dry in 9 to 24 month, depending on the type of wood. I do twice-turn some bowls but it is a mix. I have the blanks stored all over the place in my shop and garage. It takes patience and time but if you are always adding to your stock you will eventually have a steady stream of dried blanks.
