The Forestry Forum

I am milling some white oaks and am wondering about the lighter sap wood that comes in about 2 or 3 inches from the outside of the log on a 20 inch log.

Does this wood make as good a lumber as the inner slightly darker heartwood?

If the logs are not rotten, the sap wood is just as good as the heart.   Regards, Clark

I've not cut and dried much white oak yet, but have heard that the sapwood if not cut off has a tendency to make it cup more in drying - that is shrinks at a faster rate and shrinks more.

Quote from: rwachtell on May 11, 2018, 07:49:39 AMDoes this wood make as good a lumber as the inner slightly darker heartwood?

This question sorta follows the "almost/never" situation and the answer depends upon the intended use.  I use White Oak for bridge/trailer decking and the sapwood rots before the heartwood.  Actually this is true with any species that I am familiar with, even Sweetgum.  ;D

The cells that make up sapwood and heartwood are identical. The heartwood you see was once sapwood. The difference is in what is inside the cell lumen, the hollow cavity inside the cell walls. As the cell dies it is infilled with extractives, inert... tree poop and other chemicals. If there is enough in there to actually bulk the cell it can block some shrinkage. In most woods no, we don't see tables of heartwood and sapwood shrinkages. Shrinkage is the moisture within the cell wall departing and the microfibrils that make up the wall moving closer together, it has nothing to do with what is inside the cavity of the cell unless that is packed mighty tight. Depending on what else is in the extractives it can be insect and or decay resistant. Every other critter but us recognizes heartwood for what it is, toxic, spent, devoid of nutrition. The heartwood of some species is decay and insect resistant, the sapwood of no species is decay resistant.