The Janka scale is a simple way to see how tough a wood really is. It measures how much force it takes to press a small steel ball into the wood. The higher the number, the harder the wood.
Red oak comes in around 1,290 pounds of force which makes it a popular choice for furniture and flooring. Hickory is even harder, perfect if you want something that can take a lot of use. Softer woods like elm can still be great but on something like a dining room table might need extra protection like a polyurethane finish.
The actual Janka test is done by pushing an 11.28 millimeter steel ball halfway into a piece of wood and recording how much force it takes. While the results are helpful for comparing woods, it is not the only thing to consider. Grain direction, finish, and how the wood is used all affect how it will perform over time.
Knowing the Janka rating can help you pick the right wood for your home. If you have kids or pets you might go for something higher on the scale. If you love a softer rustic look you might choose something a little lower and embrace the natural wear over time.
Bibliography
- Wikipedia, Janka Hardness Test
- K-Timber, Understanding the Janka Wood Hardness Scale
- Superior Hardwoods, The Janka Hardness Scale — Testing Flooring Durability