Skirting Board Mouldings

Slice horizontally through a tree, running the saw parallel to the ground (perpendicular to the trunk), and you'll see the annual rings (one new one added each year) making up the cross-section. Cut vertically through a tree trunk and you'll see lines inside running parallel to the trunk formed by the xylem tubes, forming the inner structure of the wood known as its grain. You'll also see occasional wonky ovals interrupting the grain called knots, which are the places where the branches grew out from the trunk of a tree. Knots can make wood look attractive, but they can also weaken its structure. Physically, wood is strong and stiff but, compared to a material like steel, it's also light and flexible. It has another interesting property too. Metals, plastics, and ceramics tend to have a fairly uniform inner structure and that makes them isotropic: they behave exactly the same way in all directions. Wood is different due to its annual-ring-and-grain structure.

Hardwoods typically come from broad-leaved

The inner structure of a tree makes wood what it is—what it looks like, how it behaves, and what we can use it for. There are actually hundreds of different species of trees, so making generalizations about something called "wood" isn't always that helpful: balsa wood is different from oak, which isn't quite the same as hazel, which is different again from walnut. Having said that, different types of wood have more in common with one another than with, say, metals, ceramics, and plastics. You can usually bend and snap a small, dead, tree branch with your bare hands, but you'll find it almost impossible to stretch or compress the same branch if you try pulling or pushing it in the opposite direction. The same holds when you're cutting wood. If you've ever chopped wood with an ax, you'll know it splits really easily if you slice with the blade along the grain, but it's much harder to chop the opposite way. We say wood is anisotropic, which means a lump of wood has different properties in different directions.