Wooden furniture and wooden accents can be found in most homes. These are not just beautiful but are also warm and durable. When properly cared for, wooden furniture and accessories can last for a long time. There are antique wooden furniture pieces that are carefully preserved and this has allowed generations to enjoy the beauty and charm of these priceless pieces.
Wood is neither a substance or an element. It is actually a heterogeneous mixture. Which means it is composed of elements or compounds that are present in different concentrations inside the wood body.
A material can be an element, compound or mixture.
An element has identical atoms bound together and an example of an element is hydrogen, calcium, nickel, aluminum, and gold to name a few.
A compound is composed of two or more elements in a certain ratio. A compound may be broken into individual elements by breaking the bonds between the two.
Examples of compounds are salt, water, carbon dioxide, and ammonia to name a few.
Finally, mixtures contain two or more elements in non-specific ratios. You will be able to separate the individual elements.
The composition of wood
Wood is made up of a number of compounds such as lignin, cellulose, water, hemicellulose and more. The relative composition of wood differs from one wood species to another. It does not have a fixed chemical formula like a compound, therefore, wood is a mixture. It is a heterogeneous mixture because the constituent compounds are mixed unevenly in a wood sample.
To study the composition of wood, it is not enough to simply use one type of wood species. There are numerous wood species and each one has qualities and properties that can affect its composition. The composition of wood also varies depending on its stage of development. Earlywood contains more water and more moisture while latewood has less water content and therefore less moisture. This is one of the reasons why earlywood trees are heavier compared to latewood trees.
Other properties of wood
Similar to a sponge, most types of woods float and have specific gravities at around 1.0 or less. But not all wood is this light. There are tropical hardwoods that will never float because these are heavier compared to water. Lignum vitae (Guaiacum officinale) is the known heaviest wood and this has a specific gravity of 1.05 when green.
Meanwhile green wood or wood from a newly felled tree or wood that has not seasoned well has a moisture content from 30% to over 200%. Green wood is not a good material for burning and for the building. It has to be seasoned completely to remove moisture and to reduce rotting and pests.
The weight of the actual wood is not that easy to calculate. When we say the weight of wood, this is only the wood organic material. It is a bit complicated because wood has varying moisture content throughout its developmental stage. Moisture and other minerals bind with the organic walls of wood creating one compact material. But once the moisture of wood goes below 30% then it starts to grow lighter.
Above 30% which is the saturation point of wood, the physical and mechanical properties of wood remain. The cellular structure of wood is “full” and water has completely bonded with the wood material. Wood here has completely expanded and any free water will remain in the wood pores and in the lumina.
Wood begins to dry up as soon as it is cut and processed but it can take a lot of time before the drying or seasoning process is complete. When the moisture content is below 30%, all the free water has evaporated and the bound water starts to be removed from the wood material. Just like a sponge out of the water, the wood cells start to shrink. The specific gravity of the wood increases while the wood becomes stiffer and drier.
Wood is not an element and it is not a substance. It is classified as a heterogeneous mixture because it contains a mixture of compounds in varying proportions. Wood is composed of different elements and compounds and these are responsible for varying characteristics in different wood species.