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Turning Green Wood

D

Desert Pete

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Apr 11, 2007
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So, I came across a lot of alder logs that I decided to use for bowls, bird houses and boxes. Rough turning some of this wood has been a real experience. The bird house bodies seemed to turn OK but they developed several small cracks which may glue up allright. Time will tell.

Roughing out a bowl blank is a whole different story. By the time I turned through the junk and got it to round it is about 7 inches in diameter. What was really interesting is that cracks were forming as I turned! I left the lathe to take a phone call and came back to find one really long crack had appeared in my absence. Possibly, this wood is not as green as I think but it is pretty moist.

Is this normal when turning green wood? Is it related to the species of wood? Or, is this just a bunch of logs best suited to fire wood?
 
Desert Pete said:
Is this normal when turning green wood? Is it related to the species of wood? Or, is this just a bunch of logs best suited to fire wood?
Click to expand...

I turn green wood almost exclusively. Some species are super stable and present very few problems. Others require a little more care during turning to deal with the inevitable minor cracks and distortions that appear as the wood dries (during and after turning). A few species are just not worth the time and effort required to deal with their desire to self-destruct.

Unfortunately I can't offer any specific help on the alder. I haven't run into any in South Florida.

Ed
 
green wood

Hi pete
I turn a lot of alder here in oregon so i understand what your going threw...
Green alder is really wet when fresh cut ...i will let it set about a month before I do anything with it ...then it turns pretty decent.
I have had really good luck with soaking the blanks in dish soap...not dishwasher soap but the kind used for washing by hand like AJAX of something cheap...I use a plastic container big enough for several blanks for bowls or boxes or whatever...mix the soap with water..gallon soap to 1 gallon water works best for me...let them soak for about a week then take out and let air dry ( you can turn immediatly but I prefer to let them dry..less mess) you will get some warp from rough turned but no cracks.
Alder actually dries pretty fast if you stack in a nice cool place where the sun doesnt get to it and spalts easy .
Here its readily availiable and cheap to get ...thats why i use it ..make nice projects i think.

Good luck and have fun
Bob
 
I also have recently turned some alder, about two doz blanks, and have no trouble with cracking. It drys so fast that I'm sure the cool humidity here on the coast is the reason. After it drys I'm not as pleased with it's turning potential as it is still very soft. As suggested the soap bath may help. Does anyone know of a resource that focuses on the properties of woods specific to turning, maybe a catalog of the top 50 woods turners use and why?
 
Desert Pete,
If you are in the desert, then that can be part of the problem. Low humidity will dry it out too fast, and that causes cracks. Also sun and wind add to this. I have noticed that trees that have been down for a year or so and then cut into turning blanks tend to crack a bit faster than really green wood. I have only turned a few pieces of alder, and it stablilzed fine. I do use the LDD soak. I haven't noticed that it prevents cracking or movement, any more than carefully air dried of DNA soaked pieces. It does make sanding a lot easier. However, I do turn green to final thickness, then let them dry and warp, then sand and finish. This may get different results if you turn thick, and then dry, and then final turn. Don't know, as I never turn this way.
robo hippy
 
Another tip is to spray it with water while your turning especially if it's going to take a while to turn. Whenever I leave the lathe while turning green stuff I put a plastic bag over it. That keeps it pretty much in the state you left it without letting it crack.
 
Assuming red alder as a left coast hardwood. Not really much worse than other woods in its tangential/radial shrinkage ratio, as you can see at http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm chapter 3. Since it won't really shrink a lot until it's below ~30 moisture by weight, and it carries a lot of spare water when green, it almost has to be low humidity and perhaps partially dry stock that's doing it to you. If it's a long way to the FSP, you've got longer to dally than with partially dry wood.

Wood can lose a bunch of water in the log, causing radial checks to open, then pick up a bit of moisture in wet weather to close most of them to the naked eye. Though gone, you'd best not forget them, or you'll spend a lot of time turning, only to rediscover them, to your sorrow. Knowing a bit about how wood checks will tell you where to look for them, and most of the time they'll leave some trace you might have detected if you'd looked for darker lines in the right direction and place. A wipe with water or mineral spirits will often reveal checks if you look for wicking of liquid into the gaps.

Couple of people have mentioned soaking. Stands to reason that if you get the wood wetter, it won't dry out. Trouble is, you have to get it below the FSP sooner or later, and there's not a lot of help in as little glycerol as you may get into the wood in a few hours, especially as you'll be turning (and throwing) it away first. Brushing a fresh turning with the detergent/alcohol mix will slow the loss of water, since glycerine is hygroscopic, but it won't keep preexisting stuff closed.

Cut out a 2" long wedge from center to sapwood, weigh it, then boil it out in the micro or cook in the oven at 150 for a couple of hours. Reweigh until it's dry. Don't worry about checking, you're checking for % moisture content. Here's thinking you're at less than half the green value. Probably closer to a third. That can put some of those radial cracks that form at the sapwood/heartwood junction in your way as you turn cross-grain pieces. Our local tag alder is really bad for this, as is choke-cherry and other rapidly-growing woods that colonize places in open sunlight.
 
Actually, I am in Oregon. The wood came from the Coast Range. Soaking might help. I carved a dough bowl that I kept wet when I was not working on it - turned out great.
 
Pete,
If you are ever in our neck of the woods, Newport, come by a meeting or just visit for a cup of coffee. The stove is always on in one of our shops.
 
I've had red alder dry perfectly, then had rough bowls, from the same log, split in two... like the one I unbagged yesterday
Fortunately we can get that wood SOOOO cheap (the effort of finding someone with a tree down and cutting it up), that it's not an issue to me
 
Pete,

Try wrapping the wood you are turning in the same self sticking plastic wrap that is used during shipping, then cover with a few strips of tape. The plastic prevents the loss of moisture, due to cendtrifugal force, while you are turning-therefore no more splitting. You might also want to spray a little water on the inside of the form after wrapping the object. I was recently in the 'high-desert' in Colorado. I employed this method after experiencing what you described. I didn't lose any more pieces after doing this. Good Luck!

Matt
 
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