Once Turned Bowl Thickness

[R Henrickson]

Leo pretty much nailed it. Whether a turning needs to have drying slowed or not very much depends on the wood species, thickness, shape, and defects in the surface. For me, using kraft paper, bag/sheets/etc to slow drying and reduce loss is a very easy process to increase yield of projects I have put significant time into - harvest, cut blanks, mount and cut on the lathe. I may never learn the finer points of how to be more successful without using a “slower drying method”, and I accept that for now. When I fully retire and have more time this may be an area of experimentation to learn more.

Another crucial factor is local climate -- e.g., drying conditions in the Southwest require entirely different methods than the Gulf Coast or New England.

 

[William Rogers]

Leo pretty much nailed it. Whether a turning needs to have drying slowed or not very much depends on the wood species, thickness, shape, and defects in the surface. For me, using kraft paper, bag/sheets/etc to slow drying and reduce loss is a very easy process to increase yield of projects I have put significant time into - harvest, cut blanks, mount and cut on the lathe. I may never learn the finer points of how to be more successful without using a “slower drying method”, and I accept that for now. When I fully retire and have more time this may be an area of experimentation to learn more.

Doug, I hate to burst your bubble, I have been retired for 8 years and have less time than when I was working. Just too many more things to do.

 

[Leo Van Der Loo]

Another crucial factor is local climate -- e.g., drying conditions in the Southwest require entirely different methods than the Gulf Coast or New England.

That is why you put the bowl in the bag, you take it out of your local climate and place it into an artificial climate you create in the paper bag, it does slow down the drying in all places.

Also most people's homes are conditioned to some extend and so those are not at the extreme ends of climate conditions.

 

[Doug Freeman]

Another crucial factor is local climate -- e.g., drying conditions in the Southwest require entirely different methods than the Gulf Coast or New England.

Well, not entirely different methods but adaptation to the local climate, which can be said for the wet wood turning process as well, ie in the desert SW you better have a spray bottle of water around and keep spraying the project, in the SE most of the year it isnt a problem. I handle it by drying items in the house, where humidity and temp are kept fairly constant throughout the year (I humidify the entire house in winter).

The SW will require more vapor barrier (ex: thickness of paper) vs most other places. FYI all this is a function of water vapor pressure, which is a function of dewpoint. RH% is a calculated value, ie a function of dry bulb and dewpoint temperatures. Water vapor pressure differential determines evaporation rate, hence all the discussion about what does and doesnt work in different locales. If your locale is in your environmentally controlled home, the vapor pressure differential between the micro climate around the wrapped piece vs the outer environment it evaporates to (your house) is the same no matter where you live. If you choose not to control the environment where the turnings are stored, there is no consistency to the drying process, creating wide variability in results, which drives all the discussion.

 

[Tim Tucker]

I wonder how many woodturners actually KNOW the relative humidity in their shop? It will cost all of about...$20 to equipped/arm one with the information - via a digital thermometer/hygrometer. You can find all sort of configuration of these in the Inside Garden Dept. @ Lowe's and likely Home Depot and Menard's - depending on where you live. Here is a Google search page for some sourcing:

digital hygrometer thermometer humidity meter.

The ability to KNOW what the humidity and temp. in your workspace are very helpful in choosing how you want to dry wood....

 

[hockenbery]

The ability to KNOW what the humidity and temp. in your workspace are very helpful in choosing how you want to dry wood...

For air drying wood you have to know the temperature and humidity of the drying area to know what the moisture content you can achieve. My drying area is 50% humidify average temp 70F. My wood will dry to about 9%.
The forestry service chart below will tell you what MC dry is in you drying area
.

 

[Leo Van Der Loo]

The above is nice for when you are drying planks, but doesn't help with the slowing down of drying bowls, to prevent the splitting of these pieces.

Like I said the bowls in a brown paper bag are in an artificial created environment, where homes and shops are normally not experiencing the extremes and much more suited to the humans that inhabit these places

The only thing that is affected by drier and warmer/cooler homes/shops is the drying of the paper bag, placed in a spot without fans or wind (like heating/cooling ducts) blowing over it, the drying is not that much affected by these small differences in peoples created environments.

This is my experience from the last 40 years, as I say, it works.

 

[hockenbery]

The above is nice for when you are drying planks, but doesn't help with the slowing down of drying bowls, to prevent the splitting of these pieces.

I use bags too. Totally different part of drying. Final couple of months I take the bowls out of the bag.
The equilibrium MC in my drying room will be around 9%. Since that environment is similar to most homes the bowls will be fine.

If I were to dry bowls in my shop or a shed Equilibrium MC will be over 12%. I prefer 9% before returning.
For once turned bowls not so important as the warp is part of the piece.

 

[GRJensen]

I use brown paper grocery bags and shavings as well for twice-turned bowls. Before I put them in the bag I don't leave any sharp edges around the rim ... rounding them over slightly (inside and out) reduces the chances of cracking.

 

[Leo Van Der Loo]

I use brown paper grocery bags and shavings as well for twice-turned bowls. Before I put them in the bag I don't leave any sharp edges around the rim ... rounding them over slightly (inside and out) reduces the chances of cracking.

I would not use shavings in the bag with the bowl, the reason is that you prevent the air to get the moisture to exchange on/into the brown paper bag from the wet blank, as the shavings block that exchange.

The other thing is that you can/will create is trapped moisture in the shavings and create the condition for mildew to thrive, I would suggest you will get better results without the shavings in there, just IMO, and as others have reported that to happen.

 

[robo hippy]

You can use dry shavings. There are some that use desiccant beads to dry bowls in, you know those little packs of beads that wick out moisture from electronics when in shipping... I have heard of some using cat litter as well. What it does is draw out moisture, but then it forms a shell of protection around the bowl. A bit higher moisture level than the stuff outside the shell, but drier than the bowl itself. This would be similar to using a brown paper bag inside a plastic bag. Not enough moisture for the bowl to mold or rot, but a slowing of the moisture loss as the bowls comes to equilibrium. Wet shavings and your bowl will get moldy, and that mold is difficult to get out....

robo hippy

 

[John Jordan]

Thanks for all the information . I turned the bowl yesterday to around 5/16” thick, weighed it and put in a lawn and leaf bag overnight. No cracks this morning. I turned it the same as a natural edge (from the bark side). It is warping, diameter now is 11 7/8” X 11 1/8”. I’ll keep it in. the bag for about a week and then let air dry.

View attachment 42632View attachment 42633

Blow it as dry as you can, and rather than a plastic bag, a paper bag. This will reduce staining. I just put them in a cabinet with the door closed. There's no reason you should have any issue with those at all if there were no checks to start.

Hope you're doing well!

John

 

[William Rogers]

I wanted to complete this thread. I finished the bowl. I took the advice here, but sometimes I was farther along and got away with a few things. Bowl looks good IMO, but this is not my thing. It will be my only and last once turned bowl. It does have a slight rock to it.

 

[Doug Freeman]

@William Rogers just curious why it will be your last 1-turn bowl? Might be some aspects of the process that some help might make you more of a fan. I started with 2-turn, but after doing several 1 turn and working through the process differences, I much prefer 1 turns, bowls or hf’s. I will say that for utility bowls, I prefer flat round rims and bowls, and 2-turn them.

 

[William Rogers]

@Doug Freeman I don’t think the process so much, but feel limited in the rim design. And I realize you can’t control the warp. This bowl has a slight warp and I couldn’t do much to eliminate it.

 

[john lucas]

Get John Jordan's video on the Aesthetics of wood. It teaches you how to plan for the warping.

 

[Tim Tucker]

Get John Jordan's video on the Aesthetics of wood. It teaches you how to plan for the warping.

Yep - an excellent resource for understand how wood moves and understanding how to maximize grain orientation.

 

[Norm Marentette]

The above is nice for when you are drying planks, but doesn't help with the slowing down of drying bowls, to prevent the splitting of these pieces.

Like I said the bowls in a brown paper bag are in an artificial created environment, where homes and shops are normally not experiencing the extremes and much more suited to the humans that inhabit these places

The only thing that is affected by drier and warmer/cooler homes/shops is the drying of the paper bag, placed in a spot without fans or wind (like heating/cooling ducts) blowing over it, the drying is not that much affected by these small differences in peoples created environments.

This is my experience from the last 40 years, as I say, it works.

Do you close the bag? How long do you let bowl stay in bag? Still trying to figure best way to dry my rough turned bowls. Some are in garage and. some in crawlspace. All are doing well so far with anchor seal.

 

[hockenbery]

@Doug Freeman I don’t think the process so much, but feel limited in the rim design. And I realize you can’t control the warp. This bowl has a slight warp and I couldn’t do much to eliminate it.

If the goal is round - twice turned gets you as near to round as wood will let you.

I personally get more varied rim designs in NE bowls.

There is a fair amount of control available with NE bowls by choosing logs, openings, height to width.
Use the warp. Make it your helper.

Rim contours come from log contours.
Round logs yield classic symmetric rims

Many different rim contours are provided by Crotches, flat sided logs, buttress root sections, ribbed logs, hollow logs….

Google
Bert Marsh, Jerry Kermode,

 

[William Rogers]

I need to clarify. NE and hollow forms I would consider once turned. The bowl I turned is more utility and that type of bowl is what I don’t want to turn again.

 

[hockenbery]

I need to clarify. NE and hollow forms I would consider once turned. The bowl I turned is more utility and that type of bowl is what I don’t want to turn again.

I’m partly with you on that. Twice turned bowls are usually my first choice for a functional bowl

Surprising to some, Many NE bowls are functional too. I usually remove the bark so they can be functional.

 

[Leo Van Der Loo]

Do you close the bag? How long do you let bowl stay in bag? Still trying to figure best way to dry my rough turned bowls. Some are in garage and. some in crawlspace. All are doing well so far with anchor seal.

Yes Norm, the bags are closed, so that the drying is slowed down while the humidity is held high at start and slowly gets less as the bowl dries.

Time depend a bit on type of wood and size and thickness of the walls, I often forget that I have some bowls still sitting in a bag, just the first week or so I do check for mildew (wipe dry and change for a dry bag if that happens) most times the bowls are dry enough to take out of the bag after 6 weeks or so, they can then dry out in the open air.

 

[robo hippy]

I have never tried it, but you can make a plywood ring to go on the outside of a bowl, and under that pressure, the bowl will come out more round. For me, the warped bowl is artistic. My favorite is Pacific Madrone which warps to no rhyme or reason. You can't plan for it. Even cored sets can warp in different directions.

robo hippy

 

[Norm Marentette]

Yes Norm, the bags are closed, so that the drying is slowed down while the humidity is held high at start and slowly gets less as the bowl dries.

Time depend a bit on type of wood and size and thickness of the walls, I often forget that I have some bowls still sitting in a bag, just the first week or so I do check for mildew (wipe dry and change for a dry bag if that happens) most times the bowls are dry enough to take out of the bag after 6 weeks or so, they can then dry out in the open air.

Thanks Leo. I will give It a try.

 

[hockenbery]

I have never tried it, but you can make a plywood ring to go on the outside of a bowl, and under that pressure, the bowl will come out more round. For me, the warped bowl is artistic.

You can also use clamps tensioned with heavy rubber bands to increase the warp.
We used these In a class I took from Johannes Michelson. These encouraged the wood to bend a bit more than the warp.

 

[Don Wattenhofer]

You can also use clamps tensioned with heavy rubber bands to increase the warp.
We used these In a class I took from Johannes Michelson. These encouraged the wood to bend a bit more than the warp.

That is how he shapes the brim of his hats.