Full Chisel Blog

April 25, 2008

Working Green

Filed under: Of Interest,Uncategorized — Stephen Shepherd @ 7:49 am

Working Green

 

No, no, no, this is not about how to ‘be green’, but working green wood.  Now that is not the color, it just means it is fresh cut and has not dried out and shrunk up.  Green wood has advantages and disadvantages.  For one it will shrink, probably split and can twist, wind, bow, cup and warp.  But if that is not a concern it is great stuff to work with.  And it can be glued with hide glue even green wet wood.

 

Fresh cut, unseasoned green wood is excellent for chair making as the shrinkage can be used to advantage.  If the upright legs of a chair such as a ladder back are made of green wood and all the rest of the parts, dry seasoned wood, then when it shrinks and all of those socket holes shrink it will lock the chair together in addition to the hide glue holding everything together.

 

Or the seat of a Windsor chair is made of green wood and the spindles and legs are dry wood, then the same thing happens, the socket holes shrink around the tenons of the legs and spindles.  Also other combinations of dry and green wood have been used with great success.

 

Turned pieces are sometimes roughed out when green allowed to season (easier because the bulk of the wood has been removed) then returned when dry.  When a piece is turned from green wood when it dries it will become slightly oval.  If it is a square piece when it dries it becomes a slight diamond shape.

 

How wood seasons

(ignore the ilovewood.com it is now www.fullchisel.com)

 

One other slight advantage is that when working green wood there is no static electricity that makes the shavings stick to everything.  Dry wood will produce the static and the shavings and chips are attracted to most surfaces.  One disadvantage is that it can rust tools because of the moisture, so it is important to keep the tools green.

 

Green wood is also much easier to work, ever try and hew an air dried white oak log?  But working a green log is much, much easier, although the log is heavier.  Green pine works like butter.  Under a chisel or plane iron the work is smooth and creamy, whatever that means.  Sawing can produce some fuzz but that can be cleaned up with a low angle very sharp plane.

 

Here is the real advantage and something I have wanted to get out there, green wood becomes air dried wood which is a much better product to work with as opposed to kiln dried wood.  Now kiln drying is a new thing and was not done in the mid nineteenth century as a matter of course.  It may have been done in isolated places but the large percentage of wood was worked green or air dried.

 

Kiln drying was introduced in the late Industrial Revolution to keep up with the demand for dry wood for increased manufacturing.  So in my time period (mid nineteenth century) it was not around, so all dry wood was air dried.

 

Cooking wood to dry it out will forever change the structure and chemistry of the wood.  This is why when you steam wood, heating it above 185º, it cooks the fatty acids in the lignin and when it cools it becomes solid, on reason steam bent wood stays in place.  Once it is cooked that hot the wood is harder and more brittle than air dried wood.

 

The difference between kiln dried and air dried woods is noticed in tone-woods by musical instrument makers (Stradivarius didn’t have kiln dried wood) and chair makers; I have noticed a big difference myself.  Kiln dried wood doesn’t have the same feel as air dried wood, and air dried works better under a tool.  Knots are easier to plane when they are green or air dried but not so easy when kiln dried.

 

Kiln dried wood is also more difficult to glue than air dried wood, there are problems with what is called a refractory surfaces and case hardening that effect how easy they are to glue.  Kiln dried wood may cause problems with finishes.

 

That is why I like green wood and am very fond of air dried wood and try and use it as much as possible.  I do use kiln dried wood because I can’t always get green wood and few suppliers offer air dried lumber.  Give green wood a try and if you can get some air dried wood, buy it and give it a try, you will be pleasantly surprised.

 

Stephen

3 Comments »

  1. Stephen,

    Good writeup. I really like the diagram showing how wood moves as it dries. I track over 25 blogs at http://www.unpluggedshop.com, and this one is quickly becoming one of my favorite.

    Thanks,
    Luke

    Comment by Luke Townsley — April 25, 2008 @ 9:08 am

  2. I learned a lot from this. Thanks for posting. Please continue to share your knowledge. I’m a house-builder, not a furniture-maker, but understanding wood is always a good thing.

    Comment by Joe Cottonwood — April 25, 2008 @ 4:18 pm

  3. Luke,

    Thanks, I enjoy your web site and blog as well.

    Joe,

    Thank you and This is more than a site about furniture. Being as you are a builder I will add some stuff that you might be interested in, it is related to nineteenth century woodworking.

    Stephen

    Comment by Stephen Shepherd — April 25, 2008 @ 5:46 pm

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