Wood Anatomy and Variability
It is helpful to think of wood anatomy on a microscopic level as a tightly bound bundle of drinking straws with the long axis of each straw parallel to all the others in the bundle. The two basic features of this bundle of straws are:
1) the material that makes up the walls of the straws themselves (and the structure of the wood)
2) the open cavities within each straw.
It might be counterintuitive to think there are air cavities inside solid wood, but there are. This is why old timber harvesting operations were able to float logs on rivers to sawmill. The air inside the wood made the logs buoyant.
When a tree is harvested, the wood in the log also contains residual moisture from natural biological process inside the living tree. This moisture is classified by two types:
1) liquid or “free” water inside those straw cavities
2) water molecules which are chemically bound within the walls of the straws.
It naturally follows that lumber sawn from logs and products produced from that lumber contain moisture as well. However, wood has the ability to exchange water vapor with its environment; therefore, actual wood moisture content (MC) is dependent upon the relative humidity around it.
This ability to exchange water vapor is perhaps wood’s most significant and misunderstood characteristic particularly as it relates to customer expectations. Cyclical gaining and releasing of moisture results in the characteristic shrinking and swelling wood products like flooring can demonstrate as humidity levels change seasonally.
Another unique characteristic of wood: it displays different properties and behavior depending on the orientation of the board to the growth rings (grain) in the tree. That is, depending on the grain pattern on the surface of the board, one can expect a different response to the MC changes that occur naturally as the calendar flips through winter, spring, summer, and fall.
The good news is that normal MC fluctuations inside a climate controlled structure are typically not sufficient to cause significant or even noticeable distortion of installed wood products, assuming the wood was at the proper MC when installed. While wood will naturally exchange moisture with its environment and even display slight dimensional changes over time, it is quite stable when the environment is well controlled around it, like inside a home.
Wood is a remarkably flexible, strong and beautiful material, expertly engineered by nature for a variety of uses. At Augusta Surfaces we respect these aspects of this unparalleled material and do our best to provide our customers the best it has to offer.