Green wood, shrinkage, cracks...

[Mike Holbrook]

Yes, I know this has become something of a theme for me. I am having a little difficulty with one particular aspect of working green wood though. Prevention of cracking and shrinkage if often referenced but briefly. I am not finding much detail on specifically how this unique aspect of green wood gets handled. I am finding three main methods of slowing/preventing distortion in green wood: 1) placing work in plastic bags, 2) burying the work in sawdust or shavings, 3) toss the work in some sort of kiln. My question isn't just about methods though, I am trying to figure out what changes these particular methods make in the wood itself. Does slowing the evaporation rate of the moisture in the wood: 1) prevent cracking and other distortions from happening, reduce these distortions to manageable amounts, just delay the inevitable? I have also read that some woods are more subject to distortion issues than others, although I do not find specifics related to specific woods.

Any help, suggestions, methods, information regardign shrinkage in specific woods... is appreciated.

[Noah Wagener]

I think you are supposed to coat the ends in wax. I do not think you want to throw it in a kiln. You want to work it green right? I think i read something by Jennie Alexander where he said if you are not working it immediately, submerge it. But that is just for preserving its workability, not safely drying like you asked about. Maybe put it in a kiln when you have finished working? That book Understanding Wood by Bruce Hoadley had info on drying wood. I melted some paraffin wax and put it on some big birch logs i found and they have not cracked. I think it is more the wood and not the wax though.

I am curious if you can simulate green wood by submerging dried wood? are most chairs made from greenwood?

[Jim Koepke]

I am finding three main methods of slowing/preventing distortion in green wood

Mike,

What may be a good source of information is here on SMC. A lot of folks on the Turner's forum turn green wood. Maybe do as search with the SMC search function for > green wood denatured alcohol <.

One of my recent projects was making a scoop out of birch. After turning it green on a lathe and doing some of the preliminary carving I soaked it in alcohol inside a sealed plastic bag. After all the alcohol was absorbed the scoop was put inside a paper bag which was put inside of a couple more bags. This sat for about a week. It is now dry and without cracks.

I think the theory is the alcohol mixes with the water or displaces the water in the wood and evaporates taking the water with it. My scoop came out fine.

I have been meaning to ask a question in the Turner's Forum about the different alcohols such as isopropyl versus denatured, but have not gotten around to it.

I melted some paraffin wax and put it on some big birch logs i found and they have not cracked.

Noah,

I hope you have stripped the bark from your birch if you haven't split it. The bark holds in moisture. From what I have read the wood may rot before it dries if the bark is left on.

I split out a billet or two for making some mallets. I did coat the end with wax in hopes of preventing any splitting.

jtk

[Mike Holbrook]

Noah, yes I have been reading the sections in my copy of "Understanding Wood" Water in Wood & Coping with Wood Movement. There is lots of detail in how moisture moves in wood but I have not found much yet on stabilizing green wood workpieces which is what I am after. I checked the Turner's forum and found some good relevant information in a thread on Green Wood. Turners typically work with bowl or spoon size blanks that are known smaller sizes that I imagine have a certain amount of predictability due to the consistent sizes.
http://www.sawmillcreek.org/showthre...ght=Green+Wood

Two substances that I found turners commonly used to prevent splitting are Anchorseal (Anchorseal 2, specifically for hardwoods) and DPS both available at U.C Coatings. Anchorseal is typically used to coat the ends of logs. DPS is used as "A stabilizing end coating for dried wood. DPS (Dried Parts Stabilizer) is a water-based, wax-less, semi-permeable coating that protects dried wood parts during storage and shipment." The turners seem to use DPS on worked wood.

Here is some reference to bagging and storing in sawdust or shavings with some other good links in it.
http://www.sawmillcreek.org/showthre...ght=Green+Wood

[Bob Glenn]

Mike, I've tried storing green maple in trash bags, but found it spalted pretty quickly. I've been successful putting a couple green billets in our deep freeze to keep them from cracking. (don't tell my wife) I came across some really nice straight red oak quartered logs left over after my sawyer did some custom quarter sawing. They were free and too much to rive and carve into spindles and arm bows, so they are currently tethered to my boat in our lake. I'm hoping they will rive and carve as nicely when I pull them from the water as they did after they were cut.

[Mike Holbrook]

I have a couple pieces I have been playing with in a plastic bag with shavings taken from my early work with drawknives and spokeshaves. I thought I would play around with pieces that are for play to find out what happens before I commit something nice to a trial method I am not familiar with. I will probably order Anchorseal and DPS next week too.

[Mike Holbrook]

Just an update on my experiment to reduce/control shrinkage in green wood. For a period of 2-3 weeks now I have been storing various small green wood projects in a simple plastic garbage bag with the shavings I took off them with, drawknives, spokeshaves and Iwasaki rasps. I can report that the two pieces I put in first have yet to show any cracks. Both pieces were cracking profusely on both ends every day or two when left in the open. I had been simply sawing off the split ends every few days, yes I left them extra long.

My method has been to open the bag for periods of one to two hours on an irregular basis. So far I am very pleased that reducing cracking and managing shrinkage has not been nearly as difficult as I imagined. The pieces in the bag are from 1"-3" thick 9"-32" long, roughly shaped. The largest piece, a club for beating froes with, has a portion that is 1-2" thick no bark and the other 2/3 of its length is 3" with the bark still on. This piece has been in the bad the longest and has no cracks on either end. It was cracking badly on both ends before I "bagged" it.

Now I am studying on how long I need to "bag" wood before it is usable. I was reading a Blog by a notable spoon and bowl maker who was confessing that he often finishes wood that has only dried a week or two, although he suggests that a month of dry time is preferable. This is a much shorter dry time than I thought would be necessary. One aspect of a short dry time is apparently the thickness of the wood project. I read that thin projects like spoons and thin sided bowls dry comparatively quickly stored in sawdust or shavings.