Green Wood turnings

[MidwestMan]

I've been making bowls with wet wood and putting them in grocery paper bags filled with the shavings. Leaving plenty of wood left on to turn later of course.

I am wondering a few things.

1. Is it okay to just leave the bags alone for 6 months or more? I would consider it a big pain to open the bags every so often and pull out the bowls, and then have to repack it. Unless of course, I must do so.

2. How critical is it, to have uniform thickness?

Does anyone have good info to read about this topic?

[Dennis Puskar]

You should have coated the end grain with anchor seal to keep them from drying out so quickly.
I have left mine in a bag for over a year without any problems.

[MidwestMan]

So, what you are saying is to coat pretty much my whole bowl with a product called "Anchor Seal".... is that it?

[Tim J. Chase]

The only thing I would do different than your plan is to reach in the bag every 3 or 4 months and turn the bowl 180 degrees assuming there buried on there edge in the shavings. I lost no bowls to cracking or drying to fast the brown paper grocery bag allows the moisture to leave the wood slowly without any other coatings If fully coated with anchor seal you just leave them on an open shelf and be prepared to wait longer for dry wood to turn. The anchor seal greatly reduces the ability for the bound moisture to escape at all it is a sealer. I use it on all end grain of blanks cut and waiting to be turned the first time once turned green, I always bag in shavings from the blank and wait about a year to re turn the then dry blanks. smaller bowls than say 10-12 inch diameter will dry faster. Also My basement shop is damp compared to others so That may help keep them from cracking as I have never stored them anywhere else. I run a dehumidifier thru out the summer months in an adjacent room to keep things stable and not to humid.

[MidwestMan]

Tim J. Chase said:

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The only thing I would do different than your plan is to reach in the bag every 3 or 4 months and turn the bowl 180 degrees assuming there buried on there edge in the shavings. I lost no bowls to cracking or drying to fast the brown paper grocery bag allows the moisture to leave the wood slowly without any other coatings If fully coated with anchor seal you just leave them on an open shelf and be prepared to wait longer for dry wood to turn. The anchor seal greatly reduces the ability for the bound moisture to escape at all it is a sealer. I use it on all end grain of blanks cut and waiting to be turned the first time once turned green, I always bag in shavings from the blank and wait about a year to re turn the then dry blanks. smaller bowls than say 10-12 inch diameter will dry faster. Also My basement shop is damp compared to others so That may help keep them from cracking as I have never stored them anywhere else. I run a dehumidifier thru out the summer months in an adjacent room to keep things stable and not to humid.

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Thank you Tim. My Basement shop is not humid... not that much anyway. I'm hoping that I am not wasting my time by bagging the rough cut bowls. Due to the fact, that my bowls are unique. They have a base intact, and I am turning the log trunk longitude wise. In other words, the pith is the center of the bowl.

The following photo is a bowl on its side. It is a 2 piece product. The bowl has a base, and then there is a lower base, which is a separate "disk". (lazy susan in between)

[Steve K]

The only time I use a paper bag is when I turn to finish green. For twice turned bowls I coat with anchor seal inside and out and throw them on the floor for about a month. After that, they go on a shelf until I'm ready to finish turn them. I save nearly 100% that way.

[MichaelMouse]

Relative humidity determines how or if you want anything more than setting them on the basement floor where the RH is highest for a couple weeks, then bringing them up to a shelf to finish cure. I have 65-70% RH on the concrete, which is fine for summer. Heating season sends them to the garage.

Mostly, though, you want to mind the shape of the rough turning. Too much wood in a cross-grain (tangential) direction can pull a crack open, so round or taper your rough to redirect drying stress at an angle to the grain. On the standard capacity-turned bowl you will see that the heart remains elevated and the dimension stable along the grain, while the shoulders droop and the dimension shrinks slightly across.

My stuff ends up ~3/4 to 1" thick, depending on restyle options desired, and takes three months or thereabout to cure to 10%, equal to the basement RH. I don't coat, nor do I bag. Gave that up twenty years and more ago, along with other fads like bracing across the grain to limit shrink - guaranteed split, BTW.

Floor.

http://i35.photobucket.com/albums/d160/G...etness.jpg

Fall Storage

http://i35.photobucket.com/albums/d160/G...owling.jpg

Cured

http://i35.photobucket.com/albums/d160/G...age-14.jpg

You can see that the continuous wood on the bottom has contracted ~1/8" in 2 (6%), while the largest diameter appears to have lost 1/2" in 14.25 (3.5%). A bit of that is shoulder drop. What's the lesson? the 1/10th rule of wall thickness is not valid, and unnecessarily prolongs cure time. If you figure 5% on relatively straight grain, you'll have enough for a modest restyle, and your cure time will be somewhere around half of the 1".

The wall need not be uniform in thickness. Close is good enough.

If you haven't already, go to http://www.fpl.fs.fed.us/products/public...eader_id=p and grab The Wood Handbook. Ch4 has the RH to MC tables, and lots of info on shrink while curing.

[theeviltwinn]

Pith in the center of the bowl will probably crack regardless of what you do.

Twinn

[NCPaladin]

Everyone has their own way so....
I do bag mine but I do not put any shavings in the bag (it may cause mold).
I do anchor seal the endgrain; it looks like an hourglass since the bottom is side grain. In your case the bottom is end grain.
I think most a. slightly round the top edge as cracks often start there. b. make the bottom slightly thinner since it is side grain.
I know your orientation is different an agree with Twinn that it will be difficult to not have cracks with the pith in.
I check mine with a pin moisture meter in the base right through the bag. When down to about 14% I bring into the house for a couple of weeks.

I do think uniform thickness is important but I don't obsess about it.

Here is a link to equilibrium by city (scroll down to about page 8).
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf

[MichaelMouse]

theeviltwinn said:

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Pith in the center of the bowl will probably crack regardless of what you do.

Twinn

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Not necessarily. The heartwood starts out dryer than the surrounding sapwood, so the key seems to be keeping the RH up to expand that heartwood initially and get it to contract with the sapwood as the RH is reduced. His method seems the best as long as he can stay ahead of mildew.

On thin stuff, I find success favors equal access to both sides of long grain, using stickers so what's against the shelf won't stay wet and expanded while the upper part dries and perhaps checks then cracks.



Check the elevation.