A Woodworker's Guide to the Structure Types of Wood


Did you know that tiny vessels inside wood have a profound effect on both the appearance and uniformity of the wood? Used as pipelines in sap production, these vessels vary in size, distribution, and number. To learn more about these vessels and the different structure types of specialty woods, read the following woodworker’s guide to wood structure.

Ring Porous

When the vessels inside of a piece of wood are cut across the end grain, the vessels are considered pores, which is why hardwoods are known as porous woods. Ring porous woods, known also as open-grain woods, have larger pores in the early-wood and more uniformly sized and evenly distributed vessels in the late-wood. These woods, commonly produced from oak and ash trees, are more pronounced with distinct patterns, figures, and stains.

Semi-Ring Porous or Semi-Diffuse Porous

In some woods, notably butternut and black walnut, pores are larger in the early-wood and smaller in the late-wood, without the distinct zoning you find in ring porous woods. Sometimes ring porous woods such as cottonwoods have a tendency to possess semi-ring porous characteristics.

Diffuse Porous

When the pores of a hardwood are distributed fairly evenly across the early-wood and late-wood, the wood is said to be diffuse porous. Also known as closed-grain woods, diffuse porous woods such as yellow poplar, cherry, and maple have fairly small pores, while mahogany and other tropical diffuse porous woods can have much larger pores.


Water is contracted in softwoods via tracheid cells rather than vessel cells, which is why softwoods are also referred to as non-porous woods. Stain uptake and growth ring prominence vary widely in non-porous woods. Yellow pine usually has clearly visible rings, for example, while those found in white pain are fairly uniform and indistinct.

At Southern Lumber of San Jose, CA, we offer a wide range of specialty woods. From vanities and hardwood floors to interior and exterior doors, we carry it all. Check out our selection of lumber products on our website, and call us at (408) 297-9663 for more information about our inventory of specialty woods. 

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