....... WHY INSIST ON

Lumber that is sawn at approximately right angles to the annual growth rings so that the rings form an angle of 45% or more with the surface of the board.

Vertical grain boards are more stable, are less likely to warp or shrink and much more stable than flat grain boards.

According to the Redwood Inspection Service standards, "...clear all heart is grade of exceptional value, without peer among softwoods for both interior and exterior uses. This grade must be heartwood, well manufactured and of a uniformly high quality suitable for finish.
Most pieces are entirely clear or have no faulty characteristics.

Vertical grain wood possesses enhanced dimensional stability and will hold paints and finishes better than flat grain.