Because wood shrinks more along than across the growth rings, numerous small checks form on the surface of poles. What shape are these checks?

Because wood shrinks more along than across the growth rings, numerous small checks form on the surface of poles. What shape are these checks?

• A. U-shaped
• B. V-shaped
• C. W-shaped
• D. X-shaped

Answer: (B)

Differential shrinkage around the growth rings causes surface checks to form. Wood shrinks more along the growth rings (around the circumference) than across them (radially). When the outer layer dries, it tightens around the circumference more than the inner wood can, creating surface cracks. These cracks typically begin at the surface and split into two faces that diverge as they move inward, giving a V-shaped pattern. This V shape reflects two crack wings opening from a single surface point along the grain.

Differential shrinkage around the growth rings causes surface checks to form. Wood shrinks more along the growth rings (around the circumference) than across them (radially). When the outer layer dries, it tightens around the circumference more than the inner wood can, creating surface cracks. These cracks typically begin at the surface and split into two faces that diverge as they move inward, giving a V-shaped pattern. This V shape reflects two crack wings opening from a single surface point along the grain.