I have not had a chance to Google this topic, but I just harvested some green maple from some recently fallen trees in my area and would like to carve out a bowl or two from some of this wood while it is green. However, I realize that a bowl carved green will have a great tendency to check as it dries. I recently saw a photo of a bowl carved or turned from green apple wood and it did not exhibit a single check. That begs the question – How the heck did that happen?
If anyone has any experience with this I would surely like to hear it.
Thanks,
Phillip Anthony
Replies
Googled Info
Some research noted that some folks keep the bowl stock in a plastic bag when not being worked on to slow down the drying process. This would seem to promote mold, but I suppose that would be a relative circumstance. Spraying with water may help or not.
Another suggestion was to use Pentacryl (sp?). I do have some experience with this 50$ / gallon liquid that I used a few years back, but I cannot say with any certainty whether this is the answer or not.
Thanks.
Water watching
Philip,
One reads of many methods for slowing the green bowl drying process. Personally I use a transparent plastic bag of a size just big enough to take the bowl and allow the mouth of the bag to be tight-closed with an elastic band. The bowl is put in there with an amount of air but not very much. I like to put the bowl into the bag somewhere where the ambient air is not overdry. In Blighty, which is of medium humidity most of the time, I put the bowl into its bag outside the house then put the bag into a dark outdoor shed with no heating. The darkness is to ensure there is no excessive dehumidifying effect from a radiant heat source that might "boil" the bag.
The air in the plastic bag takes up some of the moisture from the bowl. This appears as condensation on the inside of the bag. Every 24 hours I take the bowl out, reverse the bag and put the bowl back in. When the condensation becomes a slight mist rather than lots of droplets, I dispense with the plastic bag and leave the bowl uncovered in the dark outdoor shed.
This process limits the amount of moisture that can exit the bowl each 24 hours. The bowl seems to shrink at a correspondingly slow enough rate to avoid checks and cracks. After a couple of weeks or so, when the condensation in the bag has become slight, I leave the bowl un-bagged in the dark shed. After another couple of weeks it has lost enough moisture to allow it to come into the drier atmosphere of the house without showing any cracks during the final period of drying out to equilibrium.
The plastic bag method has the advantage that it offers a better control of the drying out process than do other moisture-loss preventers. The plastic bag precisely limits the amount of air to which bowl moisture can migrate; its transparency also provides an indicator of moisture exudation via the eyeballing of the amount of condensation forming on the bag's inner surface. The time to go from "wet" to "dry enough to exit the bag" and then to "fit for the house" will vary with temperature and ambient air humidity in your locale.
Not to say that other moisture loss-slowing materials/methods don't work but many (straw, paper bag etc.) are less controllable because they are water-permeable and give no indication of the rate of moisture loss or of the approxiamte degree of moisture remaining in the bowl, as does that plastic bag.
Lataxe
Many thanks, Lataxe!
Lataxe,
I cannot thank you enough for your insightful post.
Last evening I put my test bowl away for the evening within two plastic bags. Prior to, while still Goggling for further info on the subject, I came across one suggestion which advised putting the green bowl within a bag filled with wet sawdust. On the surface not a bad idea, I suppose, but I had no sawdust and was not inclined to waste good wood for this purpose. Instead what I did was to simply spray the already checking base of the roughed-out bowl with water and slipped it into a plastic bag. I did keep it in my rather cool basement for the evening to try and control the temperature while not being worked on. When I opened the bag this morning I was glad to see that the check had not increased in any way.
When I received your post, I patted myself on the head for having already done what you so explicitly suggested. Your well thought out process was miles ahead of mine in that you use a clear bag which allows you to 'see' the actual drying process. Today, I took your lead and swapped my opaque bag for a clear one. As you said, the key is to control the drying process as best we can so that it does not take place to rapidly.
The thought occurred to me today that as old as I am (29 years old, BTW ... ) that I have had absolutely no experience with carving green wood. And just when I thought I knew it all. Wrong!
I sincerely appreciate your astute comments. I have taken the liberty of saving your words of wisdom for future reference.
Regards,
Phillip Anthony
Traditions Old & New
Philip,
The plastic bag method is my reiteration of a method shown me by one of the coppice workers of South Cumbria, where there is a thriving resurgence of green woodworking using the oak, ash, hazel, willow and other species that grow in various stretches of the Cumbria countryside. The method seems to be a "new" tradition (it involves the new tool of a plastic bag) based on various older traditions that used other wrappings to slow the moisture loss. At one time they used shavings or sawdust within a hesian bag, feeling the amount of increased dampness of the shavings or sawdust to judge the rate of moisture loss. The plastic bag is a lot clearer ('scuse pun) and more controllable, as well as better at demonstrating the degree of water-loss.
These useful methods are brought to us courtesy of many, many folk who have each refined the methods over the years. I take no credit myself therefore - a fatal lack of individualism, no doubt. :-)
My own experience tells me that one still has to be careful to keep the rate of water-loss low, especially when the critical moisture levels are reached and passed. When very wet, the bowl can lose a fair amount of water without cracking. Similarly when it has reached 10% (the usual equilibriun here in Blighty). Subsequent humidity changes may change the bowl shape a little but I haven't had one crack. When the moisture level is around 15 -20% there seems to be a greater inclination to shrink and crack with less percentage water loss than a really wet or dry bowl can stand.
In addition, the type of wood and the grain pattern can have an effect. For example, oak is very "cracky" whilst ash can be shrunk quite rapidy (relatively speaking) without self-destruction. Sworls, knots and other grain-swoops can also make a bowl more vulnerable to a crack, perhaps because the internal forces engendered by shrinking get concentrated in this or that spot by the grain-twirls. Some lads avoid such grain-gyrations but I confess to prefering them because they add interest to the bowl.
It also seems to be the case (all things being equal) that thin-walled bowls are less crack-prone than the thicker ones. Presumably this is because there is less material to form differential stress patterns in; and/or the thinner walls may warp more easily rather than crack, in bringing the shrinking forces to equilibrium.
Lataxe
Past blunders revealed
Lataxe,
Thank you for your astute observations. Once again, I am indebted to you for your time and invaluable commentary.
Your comment about oak being 'cracky' did indeed hit a nerve. A few years back I came across some oak I thought would make some wonderful bowls. When I obtained the log I was not certain as to how long it had been sitting in the field. I wrongly assumed that it had been there long enough to have dried out. Looking at the attached photo you will see just how misguided I was. Very cracky indeed.
Later on when my wife saw my dilemma she said, "Just slip a butterfly key in there to hold it together." With tongue-in-cheek, I quipped, "Great idea, dear".
Looking back on her words, I wonder if I should not have acted on her advise. Now, it may be too late for that. Or not. Today I am entertaining the thought of submerging the cracky oak rough bowl in water and letting nature take its course. If it does begin to close itself back to its original shape, I will be encouraged. However, this begs the question: Just how does a chap go about inserting a butterfly key into a cracky oak bowl and not have it end up looking like an artifact discovered in an archaeological dig?
Guess I will discover all the answers and probably a bit more in due time.
Thanks again,
Phillip
You and Lataxe have it figured out
I would add that you don't have to wait a day to carve it green, but to carve it dry, you're looking at years unless you hurry along the drying process.
flairwoodworks, you're only half right.
flairwoodworks,
Your second observation is spot-on.
Your first, however, is only half correct: Lataxe does indeed have it all figured out. Yours truly is just blindly bumbling about searching for the answers.
Thanks for your comments,
Phillip
DWD wood treatment
DWD= dish water detergent. Turners who do lots of green bowl work have developed this system for drying roughed out bowls. Some carvers (like yours truly) have also had good results with it. The DWD eliminates the potential mold problems, and seems to slow the drying process enough to prevent most checking and cracking. NOTHING is foolproof and each wood is a little different... plus there are many MANY variations in the exact techniques of applying DWD for drying woods. Even so, this has seemed to me to be very useful in dealing with green woods. Personally I think it has more potential usefullness for carvers than for turners. There have been many online discussions of these techniques and a bit of googling or archive searching here should set you on your way nicely.
Grain Orientation
I just looked at your oak bowl that split and must comment that neither DWD nor any other system that I am aware of would have saved that particular bowl. Oak is a bit tougher than most woods to dry without splitting in the first place and then when you use the entire cross section of the log end grain up there is simply no hope that that bowl could be dried without considerable splitting. You will need to study the proper ways to cut and orient bowls from green logs before you even start worrying about ways to dry them. Lots of info on this online and in books. Have fun! (REALLY, what is more fun than learning some new tricks and working on some nice wood!!!)
DWD??
Hello, bigfoot!
I have never heard of your DWD technique. However, I have several freshly cut maple round blanks that I can test this on.
As to your comments about my cracked-open oak blank, I can honestly say that that particular log had probably been down for some time and the crack was probably already there when I found it. Regardless, my better half found me looking at it this weekend and once again, took great interest in it. Having said that, i think I will have to do something with it so I can continue being fed at the table. I really hate to take my food out of a bowl on the floor. Our dog would probably take exception to that as well. Ha!
I appreciate your comments and time.
Phillip Anthony
Carving Green Wood
Phillip, I didn't read all of the above post, so I don't know if anyone pointed out that carving the bowl like you did with the grain running up and down through the piece is almost certain to fail. It can be done, but the bottom needs to be fairly deep with lots of curve around the pith and juvenile wood.
I wouldn't give up on carving just because of this, since you seem to have a ready source for good wood, but I would suggest that you turn the grain from side to side, and your results should improve.
As for using the plastic bag, I wouldn't use with maple for very long, because it will mold pretty quickly.
There is nothing wrong with spraying the wood with water while you are working it to keep it wet, and to prevent surface drying. If you are going to leave it for a few hours, just draping a cloth over it will slow the evaporation a lot.
After you get it down to the finished thickness, place it in paper bags, if it will fit. If not, use a cardboard box. This will slow the evaporation from the wood down to a rate, that the moisture from the thickest parts can migrate to the surface at about the same rate which it evaporates.
If you have gotten it down to ~ 1/2", then as it dries, it will change shape which relieves the stress. Try to stay as far away from the tight rings near the pith also will improve your success rate.
Thanks and a few more questions on green wood?
I have just started carving green maple less than 2 weeks ago. I have been carving practical, made-for-everyday-use, spoons from dry maple for years. Obiously the checking problem is a great concern for me as I've never tried to carve a spoon from green maple. I recently read of a bowl turner who used green maple as it is much easier to carve. How right he is! The bark strips off so easily and the wood carves like butter. I have some concerns as to checking, however and don't want to waste time on a piece that will be ruined by drying. Can anyone comment further on the diswasing detergent method? Can anyone comment on the green carving of maple in general? My pieces typically run no thicker than 3/4 in. at any point but usually thinner. I try to carve 2-3 hours a week. Any comments will be greatly appreciated.
Green turning
I recently started turning green wood- the trick/method I have been educated about is anchorseal. Can be purchased by the qt or gallon - I got mine at woodcraft. The best bet is to treat the end grain as soon as you cut the logs or blanks. Paint both ends. When you rough turn the blank coat the outside of the turning (bowl type shapes) and place in brown paper grocery bags and place in a cool out of the way place -9 floor of basement, closet - the higher you store it - ie upper shleves - heat rises and helps dry too fast. The brown paper bags absorb moisture and become damp. When they are dry your wood is probably dry enough to turn. You can at least remove from the bag and let it finish drying. Do your final turning and finish your project.
Phillip,
I carve green wood into bowls. I start with four inch chainsaw blade on an angle grinder to hollow out most of the waste wood. Then I put a carving dish on the angle grinder. The dish is rounded and has carbide teeth. They are not as aggressive as the chain saw blades. When using the chainsaw blades, I use two, side by side, to give me a half inch wide cut. That makes it easy to do overlapping cuts. If you don't know about "King Arthur's Tools", you should take a peek at http://www.katools.com.
After I rough out the bowl with the two tools I mentioned, it is at a thickness of about 5/8". I then put it in a paper bag and staple or tape the bag shut. I use the brown paper bags from grocery stores. These do not cause the mold that the plastic bags do. I leave it in the paper bag for about four months, with the date of cutting marked on the bag.
I lose a few bowls to cracks, but not that many. It seems to depend on how long the tree has been down before I did the carving. If I carve within a few days, I get better results. I do put wax on the endgrain of the logs as soon as the tree is felled. You can use latex paint (not Lataxe paint). That gives me a little more time to do the carving.
After I take the bowl out of the bag, I use gouges to finalize the bowl. If I want a smooth finish, I sand with a power sander.
This process is not how I started. I started carving with large gouges and a large mallet. It would take me more than a day to carve the waste out of the bowl, and it left me TIRED. No art in that part of the work. Then I found out about King Arthur's Tools, an when I bought the angle grinder, the chainsaw blades and the carbide dish, my bowl carving life changed. It got a lot more fun. Now I can get the waste removal out of the way in a few hours and not be fatigued.
Originally, I started using the plastic bag technique. I didn't like that at all. I haven't tried boiling or dishwasher soap, but I do know people who use them with success. Someone told me about the paper bag technique. It suits me and the results are good.
About grain direction -- I know one carver who did a lot of bowls with the grain going up through the bowl. He loses a lot of bowls to cracking. If you do that and include the pith, it will crack. If you don't include the pith, you need a big tree to get a good size bowl and the shrinkage will warp the bowl pretty good.
I carve with the grain going across. Sometimes I the top of the bowl is the outside of the tree. Sometimes the top of the bowl is the inside of the tree. You get different shapes and grain patterns with the two approaches.
I am not recommending my practices to you. I am merely describing them. They are not new. I got them all from others. If you want more information, Just ask questions, and I will do my best to answer them. I just want you to know that I am not trying to take you from other practices. I just wanted to let you know what works for me (most of the time). I have attached some photos of bowls and a photo of me with my chainsaw/ angle grinder.
Hope this is of some use to you.
Mel
This forum post is now archived. Commenting has been disabled