A Brief Talk on North American Black Walnut

Black walnut is a high-quality wood, primarily grown in North America, though also in Asia and Europe. Asian walnuts are generally lighter in color. Black walnuts are light dark brown with purple hues, and their tangential cross-section displays a beautiful large parabolic pattern ("mountain grain"). Black walnuts are relatively expensive, and are typically used as veneer in furniture, though solid wood is also used in high-end furniture.

Appearance characteristics: The sapwood of walnut is creamy white, and the heartwood ranges from light brown to dark chocolate, occasionally with purple and darker streaks. The grain is generally straight, sometimes with wavy or curly grains, forming pleasing decorative patterns.

Workability: Walnut is easy to work by hand and machine. It is suitable for nailing, screwing, and gluing. It retains paint and stain well and can be sanded to achieve special finishes. Walnut has good dimensional stability and moderate drying properties, and can be steam dried.

Physical Properties: Walnut is a medium-density hardwood with moderate bending and compression resistance, poor toughness, and good hot-pressing properties. Its heartwood is highly resistant to corrosion, making it one of the most durable woods even in corrosion-prone environments. Its sapwood is susceptible to beetle damage.

Main Applications

Black walnut is widely used in Europe, America, and Asia. Currently, black walnut is primarily used for furniture, small ornaments, carvings, cabinets, and joinery, and is increasingly used in flooring. In the United States, black walnut was once primarily used to make gunstocks.

Why does black walnut change color over time?

Many things can change the natural color of black walnut. For example, some elements typically darken light woods and lighten dark woods, so exposure to sunlight over a period of several years will often lighten black walnut furniture.

While some people use paint on black walnut, which will keep it darker indefinitely, it is usually clear coated or oiled. Clear coating will not completely prevent color change, but if maintained regularly, it will help preserve the original grain to a greater extent.

Some lumber producers also use steam during the drying process to try to balance the coloration between the heartwood and sapwood, but this usually results in a more grayish color to the material, and craftsmen generally prefer to avoid using colored raw materials when selecting lumber.