Which timber defect is parallel to the grain on the surface?

Which timber defect is parallel to the grain on the surface?

• A. Surface check
• B. Check
• C. Warp
• D. Bow

Answer: (A)

Surface checks are small cracks that appear on the surface and run parallel to the grain. Because the fibers run along the grain, drying or moisture changes cause the outer layer to shrink along that direction, creating a hairline crack that follows the grain on the surface. This pattern—crack on the surface aligned with the grain—is exactly what defines a surface check. Warp and bow describe distortions in the wood’s shape, not cracks along the grain, and a general check isn’t necessarily confined to the surface or aligned with the grain in the same way.

Surface checks are small cracks that appear on the surface and run parallel to the grain. Because the fibers run along the grain, drying or moisture changes cause the outer layer to shrink along that direction, creating a hairline crack that follows the grain on the surface. This pattern—crack on the surface aligned with the grain—is exactly what defines a surface check. Warp and bow describe distortions in the wood’s shape, not cracks along the grain, and a general check isn’t necessarily confined to the surface or aligned with the grain in the same way.