Wood is a porous material because of its cellular structure which allows for many internal voids (Eckelman). The plant cells located within wood are made to absorb water, as it is necessary for the functionality of the tree (“Wood and Water”, 2006). When wood first absorbs water, the water is transported and held within the cell walls. However, as these walls cannot hold a large amount of water, additional water fills the cavities of tubular cells within fibers of the wood. Wood is also categorized as a hygroscopic material. This allows for wood to naturally absorb and dissipate water within its contiguous environment. Density and water diffusivity of the wood affect the rate of absorption of water in wood (Noorolahi, Khazaei, and Jafari, 2008). The hygroscopicity of the wood aids in controlling humidity within houses. For example, if the air inside of a house is at a high humidity level the wood will naturally absorb some of this moisture in order for the environment to achieve a more balanced, stabilized state (“About Moisture and Wood”).
Woods are categorized as being either softwoods or hardwoods. Softwoods are generally from coniferous trees and hardwoods from broad-leaved trees, which are frequently angiosperms from dicot seeds. Hardwoods, unlike softwoods, display the presence of pores in growth rings. Four common hardwoods used in building include poplar, aspen, red oak, and red maple. Poplar has a fine-grained structure and has a specific gravity (ratio of density to that of water) of 25%. Aspen, another hardwood in the same genus as poplar, also has a specific gravity of 25%. Red oak is a highly porous wood and has a specific density of 75%. Lastly, red maple has a specific gravity of about 50% (Walker, 2005).
Wood is often used to build many structures, such as offices, houses, and furniture. Latex paint and oil stain are commonly used to treat wood, for both protection and decorative purposes. The purpose of these coatings is to allow moisture on the wood to evaporate, but to restrict the passage of free water into the wood (Walker). Latex paint is a formulated polyvinyl material with an acrylic resin. Oil-based stain is highly effective in repelling water as oil is hydrophobic (Dasch, 2003). A previous study by Sivertsen concluded that untreated, low density wood absorbed more water than high density wood. Their results also showed that, with a waterborne topcoat and no primer, the higher density wood sample absorbed more water (Sivertsen). However, this experiment was done using softwoods, and therefore the results may differ for hardwoods.
This experiment was an observational study of the correlation of wood species and surface coatings to the water absorption of wood. I took data on the amount of water absorbed by red oak, red maple, aspen, and balsam poplar wood of the same volume, but with varying surface coatings. My control group was left untreated, leaving the wood in its natural state. The four...