Green wood doesn’t dry evenly. The outside of a large
block of wood dries much faster than the interior of the wood. As wood shrinks, the
fibers contract in different directions and at different rates. This creates some
unusually drastic stresses in the wood, which can cause warping and cracking.
The trick in preventing cracks and distortion is for the
inside and the outside of a block of wood to dry uniformly. In drying green wood, a
kiln is ideal, because it is a controlled environment, that will periodically reintroduce moisture into the drying environment. By controlling drying temperature, humidity and drying rate many of the stresses that result in distortion of the wood and cracking are relieved.
If you do not have access to a drying kiln, don't despair. The alternative is to air dry it. To prevent green wood from distorting as it dries and shrinks, here are a few suggestions:
Green wood contains an extremely high percentage of
moisture. It is not unusual for the moisture content to be as high as 80%. If the wood
dries too fast, the wood will develop cracks. For this reason, do not leave the
wood outdoors in the hot, baking sun to dry. Wood must dry slowly in order for
it to maintain a state of equilibrium.
Process the wood shortly after the tree is cut. First, remove
the bark. A fast way to do this is to use an angle grinder with a Lancelot
chainsaw blade (shown below) to chew through the outer layer in no time.
After removing the bark, seal the ends of the wood, which
is where moisture most readily escapes as it dries, by painting the end grain
with latex paint. This traps the moisture in the wood block forcing it to find
another escape route and prolonging drying.
There
are also a number of commercial wood sealers on the market, such as Anchorseal
1, that will help control the rate of moisture evaporation from green wood,
thereby reducing the incidence of cracking and warping. Some people will even immerse newly cut wood blanks in a tub of Anchorseal 1. This particular sealer provides a thick waxy coating
that can be scraped off the blank prior to processing the wood after it has
cured.
Some carvers will also keep the sealed wood block in a brown paper bag, which allows the piece to air dry very slowly. This practice maintains a
consistent humidity level during the drying process.
While this is the simplest, easiest and most reliable way
to air dry green lumber, it is also the most time consuming. How long it takes
for the wood to dry depends on several factors. These variables include the
size and density of the wood block, the type of wood, and its initial moisture
content.
If you are using the block of green wood for a carving or for a turning, rough
out the basic shape as soon as possible. Typically, green wood is easier to
carve or turn. Some wood turners will turn a rough blank allowing extra wood to
compensate for significant shrinkage. They will then store the oversized blank
until it has thoroughly dried. It is not
uncommon for a blank to shrink more in one direction than another. A roughed
out circular blank often shrinks to an oval shape. By allowing for the
shrinkage, you can have extra wood as you turn the finished piece.
 |
| Shortly after a maple tree was cut, I processed the green wood as described in this article. After carving the manta ray, the wood received multiple coatings of dark tung oil. After this treatment, the blond wood developed a very natural looking and attractive appearance. |
Generally, the pith or center portion of the wood block
is highly unstable. Cracking often emanates from the center of a piece. For this
reason, many woodworkers will remove the pith as they rough out their carving. Or
you can avoid the pith as you are laying out your carving.
Vinyl Application Videos
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Wet Applications. Dry applications are typically recommended for most vinyl applications. For those exceptions to the rule, this instructional video explains the right way to perform a wet application. Click to Link
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Vinyl Application Over Rivets. Applying vinyl graphics on vehicle surfaces with rivets is challenging for most sign makers. Vinyl failures to these surfaces are all too common. This video demonstrates some tips and procedures, used by professional decal installers, which will make these demanding applications easier and more trouble-free. Click to Link
Vinyl Application to Corrugations. Learn how to apply vinyl graphics to corrugations in a relaxed state. Forcing films into the valleys of corrugations puts too much mechanical stress on the film. Sooner or later, the vinyl will lift or tent in valleys. Click to Link
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About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.
Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer. Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.
Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for publications, such as Signs Canada, SignCraft, Signs of the Times, Screen Printing, Sign and Digital Graphics and Sign Builder Illustrated. He also posted more than 400 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published. Vinyl Sign Techniques is available at sign supply distributors and at Amazon.
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