The Trouble With Wet Wood

As I become more experienced working with fallen trees, I have learned some invaluable lessons I would like to pass along. This will be the first. It may almost be the most important. When you begin cutting, sawing, shaping, sanding, gluing and/or finishing wood, you will find that if the wood is wet, you will run into many problems. Wet wood is not just wood moistened by water. Wood can also be wet with sap. Wet wood is often referred to as green wood, or fresh wood. This may seem like common sense to more experienced woodworkers. For us amateurs, it is often suggested not to work with this type of wood, or to only use seasoned wood. I have often wondered why a person should not. Through painstaking trial and error, now I know. It is a hard lesson to learn. When a wet piece of wood is cut, the moisture often enhances the look by making the grain more visible and the various layers of the tree pop. It makes you want to work with it in hopes it will end up a sa beautifully finished piece. Not to worry though, as you can restore this look with the proper type of finish.

Wet log cut

First off, wet wood is very hard on your tools. The water and/or sap in the wood will stick to blades, causing them to work harder and inefficiently. The sawdust created will also stick to everything, making it difficult to clean up and maintain your tools.

It will also make sandpaper less useful. You will use a lot of sandpaper to sand a wet piece of wood. In some situations, it may be useful to wet sandpaper for a specific type of finish, or to help cool the material during the sanding process. General use will not. Wet wood does not sand well and it will cause a lot of grief to you and your equipment.

Wet wood will also prevent glues from adhering properly. The water and sap will cause the glue to be ineffective. Some glues actually use a small amount of water to active its adhesive properties. The item being glued should not be wet throughout. It prevents the glue from absorbing into the wood, which will create a weaker bond. The glue will take much longer to set as well. If the glue instructions state a 24 hour period to completely set, this will not be the case if the wood is wet. The glue may appear dry, but the adhesion will not be strong and likely not last.

As with glue, finishing the product will be next to impossible if it is wet. Finish requires absorption into the wood to be long lasting and provide the desired result. Water and sap in the wood prevents it from dong so. It will remain on the surface of the wood until it dries and sets, preventing the proper finish to occur. The end result will be disappointing and will probably not last.

Wood grows under pressure too. Hardwoods grow under extreme pressure. Softwoods do as well, but to a lesser extent. When you cut wood, you release this stress. When the stress is released, the wood will warp, twist and crack, depending on how it is cut according to the grain of the wood. When you cut wet wood, the moisture relieves some of that pressure. It can relieve enough of the pressure to mask these effects while the wood is wet. Do not let this fool you. It will still warp, twist and crack when it dries or the moisture no longer relieves any stress. I have cut many pieces and assembled these almost to completion, only to see the pieces warp, twist and crack, usually ruining my finished item. At this point, there is no fixing what happens.

Do not work with wet wood. If the tree has been felled recently, there is a number of applications you can follow to season the wood. The first, and the longest to achieve is to "season" the wood. This means covering it from the elements and leaving it for a season or two (three to six months) with little to no moisture or humidity for the wood to absorb. Wood is like a sponge. It will absorb any moisture available to it.

A faster method to prepare the wood is to enclose it in a small area and activate a dehumidifier in the area. The dehumidifier will not just remove the moisture from the air, but also from the wood. This can speed up the process of seasoning the wood dramatically. Wood can be seasoned in less than a month if the space is small enough and the dehumidifier is powerful enough. Don't forget to keep the reservoir of the dehumidifier empty during the process.

Another method I have used effectively is to place small amounts of wood in an oven at a low temperature (below 275 degrees Fahrenheit) and let it bake for five or six hours. I discovered this method by accident, as I was preparing wood to be used for holding food. This method has two purposes, as it not only dries the wood, but it also eliminates and bacteria, fungus and insects that have made the wood home. This will be covered in more detail in a later article.

Finally, professionals use kilns to season wood. Kilns are larger versions of an an oven allowing for larger pieces and quantities to be cured in one place. There are other methods available to dry wood. These usually often involve chemicals, which I do not recommend. At FallenWood, we care about the environment and avoid using any chemicals in our working with wood.

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