What is “heart pine?”

Heart pine is the actual heartwood of the pine tree. Hundreds of years ago, the pine logs that were harvested were much older and larger than what is harvested now. Pine trees were able to grow large enough to develop heartwood. Now, that is not the case, as pine trees do not grow as big because they are harvested at an earlier age. Almost any pine tree, if left to grow long enough will develop a heart section.

What’s so special about the heart?

All wood start out as sap wood. This is the part of the tree that conducts water from the roots to the needles and stores nourishment. As the pine matures, the older wood (starting in the center) becomes dormant and the cell walls harden. The sap, in the form of resin, bonds with the cell wall and begins to crystallize, adding strength as well as resistance to insects and disease. This heart was prized for its exceptional strength and beauty.

As pine heartwood is exposed to ultraviolet light and oxygen, it ripens and grows darker in color. It will continue to grow noticeably richer and deeper in color for several months.

So what is the difference between “heart pine” and “antique” or “reclaimed” heart pine?

Many places will sell you heart pine. When the European explorers came to America, they found nearly eighty million acres of continuous pine forest. This forest was primarily the Long Leaf  Pine (pinus palustris), a massive tree that grows very, very slowly. This slow growth makes for very small, tight growth rings. These centuries old trees became known by the generic name “heart pine” because of their massive heart sections. Other species of pine, competing for sunlight in the old forest, grew very dense grain large heart sections as well.

Once the timber industry cut down the massive forests, new trees grew up to take their place. Faster growing species such as Loblolly and Slash Pines shot up in a fraction of the time that it took the older trees to grow. They had much smaller heart sections and their growth rings were wider and spaced farther apart. The wood from these trees, while still called “heart pine” is not as hard. It does not have the tight growth rings, is usually a mix of heart and sap woods and in cases is entirely sap wood. There is no government regulation as to what can be called heart pine and there are a few unscrupulus dealers who will sell anything to make a buck.

A more detailed look at what constitutes an antique floor can be found here.

Isn’t pine a softwood? Will it hold up to traffic?

Softwood is a generic term used to describe wood from cone bearing trees. As a rule, wood from softwood trees is much softer than wood from hardwood trees, but there are exceptions. Balsa wood is technically a hardwood, but it is a very soft wood. On the other hand, old growth heart pine is comparable in hardness to red oak.

Wood hardness is measured on the Janka scale. Red oak usually measures around 1290. Reclaimed heart pine typically has a hardness around 1290. The pine lumber that you buy at the hardware store will have a hardness of around 620.

Any wood floor is prone to dent and scratch now and then. In practical terms, what the Janka scores tells you is that that lamp that was knocked over and put the tiny dent behind the table would likely have made a dent in an oak floor just as well.