How to Read a Wood Grain: Figure, Medullary Rays, and What Makes Each Species Unique

Grain is the fingerprint of wood. Vessel arrangement, ray structure, and growth habit produce the patterns designers specify and woodworkers chase. This guide decodes the visual language — straight grain, cathedral figure, ray fleck, chatoyancy — and links each to the species that express it best. Explore textures in the Library.

Straight vs. Figured Grain

Straight grain — fibers run parallel to the board's length. Predictable, stable, and the default for structural work. Maple, Birch, and quartersawn White Oak typically show straight grain.

Figured grain — any deviation that creates visual interest. Curly (tiger stripe) arises from wavy fiber growth; fiddleback is fine, regular curl. Bird's eye comes from indented fiber clusters. Burl is chaotic grain around a defect or bud. Each figure has distinct causes and species associations.

Medullary Rays and Ray Fleck

Medullary rays are horizontal cells that radiate from the pith toward the bark. They transport nutrients and store starch. In species with prominent rays — Oak, Sycamore, Lacewood — quartersawn boards display ray fleck: silvery or tan flakes that catch light. The effect is absent in flatsawn stock. Ray fleck is the signature of Arts & Crafts and mission-style furniture. Read how milling affects figure.

Pore Structure: Ring-Porous vs. Diffuse-Porous

Ring-porous species (Oak, Ash, Hickory, Elm) have large earlywood vessels concentrated at the start of each growth ring. The face shows distinct bands — coarse texture, pronounced grain. Diffuse-porous species (Maple, Cherry, Birch, most tropicals) distribute vessels evenly; the face is finer and more uniform. Pore structure determines finishing behavior: ring-porous woods often need pore filler for a glass-smooth finish.

Chatoyancy and Interlocked Grain

Chatoyancy — the "cat's eye" effect — is sheen that shifts with viewing angle. It arises from interlocked grain: alternating spiral layers that reflect light differently. East Indian Rosewood, Sapele, and Wenge exhibit strong chatoyancy. The surface reads as three-dimensional under raking light. Oil finishes enhance the effect.

Cathedral and Arch Figure

Cathedral or arch figure is the sweeping curve of growth rings on a flatsawn face. It's the default for most lumber. Pronounced in Oak, Ash, and Walnut. Designers often specify cathedral for a traditional, warm aesthetic — or avoid it for a cleaner, contemporary look.

Using the Library for Visual Reference

Texture and figure are best evaluated visually. The WoodSwatch Library provides high-resolution references for 70+ species — compare grain patterns side by side when specifying for interiors, furniture, or 3D visualization. PBR textures extend this for architectural rendering.