Grain

Plain-English definition

Wood grain refers to the direction, size, and arrangement of the natural wood fibres that run through a piece of timber. These fibres run lengthwise up the tree trunk, carrying water and nutrients when the tree was alive.

Why it matters

Understanding grain direction is the foundation of all woodworking. Cutting, planing, or sanding with the grain results in smooth surfaces and easy cuts. Cutting or sanding across the grain leaves rough, splintered edges and deep scratches. Furthermore, screws driven parallel to the grain (into the end of a board) pull out very easily, while screws driven perpendicular to the grain hold firmly.

Common mistake

A common mistake is sanding a wooden surface in circles or across the grain. The abrasive grit will cut deep scratches that break the wood fibres. These scratches may be invisible at first, but the moment you apply a dark stain or varnish, they will show up clearly and ruin the finish. Always sand parallel to the grain.