What is an Open Grain
Open grain is a term used to describe wood pieces with relatively large grain. In addition to color and hardness, grain patterns are another unique characteristic that adds to a piece of wood's charm. Grain patterns are a result of a tree's growing patterns each season. How the wood was cut and processed when the tree was turned into lumber can also affect the grain pattern. Whereas grain pattern can be somewhat controlled, the openness or closeness of a wood grain is less controllable and depends on the species of tree the lumber was sourced from.
Open grains means that the grains of the wood are open, similar to pores in skin. Open grain wood can be hard to work with in woodworking and cabinetry due to its tendency to absorb finishes and stains unevenly due to the open grain. If an open grain wood is to be stained or finished, it is recommended that wood fillers are used to allow the stain or finish to absorb evenly throughout.