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woodturning a wet bowl

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Forum topic by coachmancuso posted 06-29-2013 06:30 PM 770 views 0 times favorited 7 replies Add to Favorites Watch
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coachmancuso

259 posts in 596 days


06-29-2013 06:30 PM

When you turn a wet bowl, Do you turn it to a regular size or leave it a little bigger? Also when you are done how do you dry it?

-- Coach Mancuso


7 replies so far

View Nicky's profile

Nicky

636 posts in 2757 days


#1 posted 06-29-2013 07:57 PM

You need to leave it oversize. 10 to 20 % depending how wet the wood is. If the blank is from a freshly fallen tree (a few weeks old) then 20% is what I’d be aiming for. It will shrink.

You want the rough cut blank drying evenly. I use Johnson’s paste wax after the initial rough cut, a light coat over the entire blank. Then I put it in a paper bag and let it sit. I just finished a few blanks of walnut. Largest bowl was 6”. I let them sit for 3 months before final turning. I live in a dry climate.

If your blanks don’t dry evenly, they will develop checks and cracks.

-- Nicky

View Wildwood's profile

Wildwood

1053 posts in 800 days


#2 posted 06-29-2013 08:55 PM

Normally get a 75% success rate turning wet bowls to ¼ to 3/8” thickness, bottoms always tad thicker. So turn thin, reverse turn, sand in finish in an hour or two.

After you have shown family and friends a couple of thin oval bowls novelty seems to where off. Since do not know if those bowls will crack normally keep in my unheated/air shop for a month or two. Never show them those that crack.

I rough turn between 5/8”, to 1 ¼ ” thickness depending upon wood species and size of blank knowing bowls may oval as they dry. Trick is have enough wood to remount on lathe and bring it back round again once dry. I just set roughed out bowls on floor at back of my shop. May try to finish turn after three months or a year or two.

-- Bill

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coachmancuso

259 posts in 596 days


#3 posted 06-30-2013 01:36 AM

I bought the blanks from Blanks 4 you at the AAW show in Tampa. They are encased with wax and dated. Some are dated 11/11 and 2 /12 and 6/12 Would the ones dated later be ready to turn they are pretty light compared to the ones cut recent.

-- Coach Mancuso

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Nicky

636 posts in 2757 days


#4 posted 06-30-2013 01:09 PM

Coach, its hard to say without any other data. I’m guessing that your blanks are large, thick chunks of wood. To fully air dry these blanks could take years (depending on the size.)

I would rough out the oldest one. Leave plenty of material for the final turning. Wax the entire blank again, and store it in a paper bag for a few weeks.

Here are some methods you could use to see if its ready for final turning.
1. A moisture meter.
2. An accurate scale. Weigh the blank after its been roughed out, then weigh it again after a week or two. If its lighter, then you need to wait until its weight is stable (keep checking every week). If its heavier, then its acclimated to your climate and ready for final turning.
3. Set your rough cut bowl , upside down, on a piece of paper and very accurately draw around the bowls diameter. Compare this after the rough cut bowl has dried for a week or two. If its smaller, or the shape is distorted, it needs more time to dry. Repeat the process until the diameters shape is the same.

The goal is to have the blanks stable in your environment. You ideally would like to have the blanks stabilize evenly or you risk checks and cracks. Wood moves based on the moisture levels, and your environment plays a major role.

-- Nicky

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coachmancuso

259 posts in 596 days


#5 posted 06-30-2013 03:21 PM

Nicky the Blanks are 4” x 3” and some are 4” x 2” I am going to weight them today

-- Coach Mancuso

View Wildwood's profile

Wildwood

1053 posts in 800 days


#6 posted 06-30-2013 04:14 PM

Drying wood is essentially a water removal and slowing down drying process. Water weight loss from wood cells is through evaporation with aid of air circulation. Wood completely sealed in wax stops gaining and losing of moisture content.

You cannot make a profit cutting trees down cutting wood into turning blanks and drying them without risk checking and splitting. That is what you get with rapid drying. So to stop the drying process wood bound for carving & turning market is completely sealed in wax. Vendors buy this wet wood from suppliers by the pound. No Vendor can guarantee moisture content of the wood they buy and sell.

So when buy wood fully sealed in wax have two choices. Scrap wax from sides of bowl or spindle blanks allowing air circulation and evaporation to take place over time. Or can rough turn and speed up the drying process. Whether you scrap sides and let dry or rough turn you risk of losing your blank to splitting & cracking. Kind of like investing what is your risk tolerance or do you feel lucky?

Because water leave a log faster through the ends of a log, end sealing with commercial end sealers, paints, or wax very important. You are slowing down this rapid water loss that leads to checking and splitting. It takes longer for water to leave through sides of a log.

If can find a copy of Fine WoodWorking on “Wood and How to Dry It, can learn about Mositure Content (MC) and ECM or Equilibrium Moisture Content and effects of relative humidity on wood. Several articles written by Bruce Hoadley.

-- Bill

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coachmancuso

259 posts in 596 days


#7 posted 06-30-2013 05:17 PM

Thanks very much wildwood and everyone else. I have a better is=dea about green wood. That is why it is so much cheaper!

-- Coach Mancuso

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