If you're making anything out of wood, you'll be dealing with wood grain in one way or another. From wood floors and fine cabinets to hardwood furniture and structural timbers, grain patterns play a part in it all. Wood grains and the terms that describe them are as varied as trees in a forest, so let’s chat about key principles of wood grain that all woodworkers should know.
What is Wood Grain?
Wood grain is the unique pattern exposed on the sawn faces of a piece of lumber. Grain pattern is among the most important aspects of any woodwork, and selecting the right one can truly elevate a project.
Wood grain is all about exposing the internal elements of a tree on the face of a sawn piece of lumber. Growth rings that are formed during a tree's development are displayed on cut boards along with other types of wood cells, like pores. Depending on the sawing technique, these features can be exposed in a variety of ways to produce unique grain patterns.
A wide range of words are used to describe grain patterns and their appearance. This table offers a brief definition and description of the most commonly encountered types, which are discussed below.
Grain Type
Characteristics
Common Species
Open
porous, rustic character
white oak, red oak
Closed
non-porous, smooth
cherry, maple
Straight
simple, parallel lines
any, usually quarter sawn
Irregular
diagonal, curving, or alternating lines
any
Flat
repeating V-shaped curves
any, usually plain sawn
Fine
non-porous, tightly packed lines
cherry
Coarse
porous, widely spaced lines
oak, ash
Curl
alternating wave pattern
maple
Burl
highly irregular swirling and sweeping lines
any
Softwood vs. Hardwood Grain
Naturally, a key factor that determines a wood grain’s appearance is whether it was sourced from a hardwood or softwood tree. Unlike hardwoods, softwoods do not have pores and therefore cannot produce open-grained lumber. Softwood trees also tend to grow much faster than hardwoods, so their growth rings are typically spaced further apart and are more defined.
Building Blocks of Wood Grain
No matter how exotic or complex some may seem, all grain patterns are rooted in the structure of the wood itself. Wood is composed of long fibers that are mostly aligned vertically along the length of the tree’s trunk. The orientation and arrangement of different fibers is what produces a wood grain pattern.
Growth Rings
Growth rings are the most important feature of any wood grain. Due to seasonal weather changes, trees often expand quickly in the spring and slower throughout the summer.
The wood formed during rapid growth is lighter in color, while the slow-growth wood is darker. This results in a contrasting light-and-dark ring pattern that is expanded each year as the tree grows.
While many are familiar with viewing growth rings on the round face of a sawn log or trunk, they appear differently in processed lumber. When a log is cut along its length to produce boards, the dark ring lines can be viewed from another perspective on each board's face, where they create unique patterns. The overall appearance depends on both the tree and the method used to saw it. A ring may appear as a single stripe on one board or a gently curving ribbon on another.
Pores
Hardwood species use long, tube-like channels called pores to distribute water and nutrients among their cells. When a piece of hardwood timber is cut into lumber, these pores are displayed in the grain of the resulting wood.
In some hardwood species, these pores are actually visible to the naked eye. Therefore, the size, presence, and distribution of pores also contribute to a wood's grain.
In some species, pores can be naturally filled by internal growths called tyloses. These small ball-shaped structures fill and block the pore tubes, preventing the flow of water and nutrients. This most commonly occurs in sections of wood that no longer need nutrients, but can also be a method for stopping the spread of an infection within a tree.
If enough tyloses are present, the pores will be completely filled and invisible to the naked eye. This can significantly change the appearance of porous wood.
Types of Wood Grain Patterns
While it's easy to get lost in the dozens of terms used to describe different wood grain types, understanding this terminology is the key to selecting the perfect wood for the job.
Open Grain
Open grain is produced when a large amount of pores are present on the face of the lumber piece. In many species, pores are visible without magnification, which gives the sawn wood a distinct rough or textured appearance. This makes open-grained woods like red oak and white oak desirable for applications that benefit from wood with unique and rustic character, like wood flooring.
Closed Grain
The opposite of open grain is closed grain, which appears in lumber with small, invisible pores. This gives the grain pattern a smooth and refined appearance. Closed-grain species like cherry and maple are popular for high-end furniture, musical instruments, and decorative woodwork.
A special exception occurs when tyloses cause open-grained woods to appear closed by filling all of the visible pores. This is especially prevalent in white oak, where older heartwood often appears non-porous due to almost total blockage of the pores. Newer wood, however, displays a typical open-grained pattern.
Straight Grain
Straight grain is produced when the wood fibers run along the length of the tree trunk without changing directions. It is defined by a pattern of mostly parallel lines that are parallel with the trunk’s centerline. The spacing of the growth rings defines the spacing of these lines, so slow-growing trees often have very dense patterns.
Straight may be the simplest of all wood grains, but that doesn't mean it's undesirable. This simple wood grain is a great choice for subtle applications that shouldn't be dominated by a bolder grain pattern, such as tool handles or structural members. It can be produced from any tree with a uniform internal structure.
Straight grain is typically produced by quarter or rift sawing a log with uniform internal grain structure. We’ll discuss these cutting styles in more detail later, but the basic principle is that the intersection of the cut and the log’s growth rings determines the type of grain that will appear in the lumber. Quarter and rift cuts both intersect the growth rings at an ideal angle for producing a straight grain pattern with evenly spaced parallel lines.
Irregular Grain
This type of wood grain is the result of wood fibers that do not perfectly align with the direction of the tree trunk’s centerline. This type of grain can be unpredictable and varies in appearance depending on the direction the fibers took while the tree was growing. It is similar in appearance to straight grain, but may run in curving, diagonal, or even alternating directions compared to standard straight grain.
Flat Grain
Wood with flat grain is defined by a pattern of repeating curved or U-shaped lines shown on its face. This type of grain is not produced by unique fiber alignment but instead results from the way the log was sawn.
Pieces of lumber that are plain sawn from an area near the outer edge of the tree produce unique flat grain patterns, while other sawing techniques can produce different patterns from the same tree. Because of this, flat grain is very common and can be produced from a wide variety of tree species. A particularly desirable type of flat grain pattern is cathedral figure, which is defined by repeating nested V-shapes that resemble a large church.
Fine Grain
Also called fine texture, this grain pattern is sourced from wood with non-visible pores, small fibers, and tightly spaced growth rings. It often results from slow-growing, closed-grained hardwoods like cherry.
Fine wood grain is prized for its sleek appearance, smooth texture, and ease of finishing. Because of this, it is commonly employed for cabinetry and decorative purposes.
Coarse Grain
Contrary to fine grain, coarse grain originates from species with visible pores, large fibers, and widely spaced rings. This type of wood grain is present in many of the popular open-grained woods, including white oak and ash.
It is well-suited to producing wood products with vibrant character and a classic wood appearance. Common uses are rustic hardwood flooring, tabletops, and gunstocks.
Curly Grain
Curly grain is a rare wave-like pattern caused when wood fiber layers grow and align in alternating directions within the tree’s trunk. When exposed in cut lumber, the two-grain directions that make up the pattern reflect light differently. As a result, a piece of lumber with a completely flat surface will produce a striking 3D wave pattern that makes this one of the most sought-after wood grain types.
Although the exact cause of curly grain cannot be definitively proven, it is known to occur most often in maple wood. The beautiful and intriguing appearance of curly maple has made it a long-standing staple of fine furniture.
Burl Grain
If curly grain is exotic, burl grain is doubly so. This rare and stunning grain pattern is produced when wood is cut from round deformations in a tree called burls. These cancer-like growths can be caused by infections or damage to the tree, and expand rapidly with a disorderly grain.
Due to this abnormal growth, burl wood grains exhibit beautiful swirling and sweeping patterns that are highly prized for decorative use. Burl can occur in any wood species since it is a result of external factors.
How Sawing Methods Affect Wood Grain
The internal structure of wood is only part of the picture when it comes to grain appearance - the rest is determined by how that structure is exposed. A log being processed into lumber can be sawn in a variety of ways, each exposing the fiber layers differently and in turn, affecting the grain pattern that appears on the cut face.
Furthermore, unsealed wood is constantly exchanging moisture with the surrounding air, which causes it to swell or shrink. Each sawing method opens the wood grain differently and encourages a certain type of shrinkage. Boards that do not shrink evenly will become warped, making the sawing technique is an important consideration.
Plain Sawing
Also called flat sawing, this method is the simplest way to slice a log. This makes it very common in lumber production, as it enables mills to generate more boards from a single tree trunk in a shorter amount of time.
Plainsawn lumber is milled by cutting a log into parallel horizontal slices along its length. Each slice intersects the tree's growth rings at a different point in their curvature, so this method can actually create boards with varying grain patterns from a single log. When a log is cut this way, the majority of slices form a 0 to 30-degree angle at the point where they intersect a ring.
When a board is plain sawn from a log with straight, uniform internal grain, the cut travels along some of the growth rings as it moves along the trunk. On the sawn faces, both the rings and the spacing between them appear wider than they actually are because they are being sliced at such a narrow angle.
As the log narrows, the cut gradually moves through the growth rings and the separate lines draw together into a V shape. This produces a pattern of repeating nested arches referred to as cathedral figure. Cathedral figure cannot be obtained through other sawing methods because it requires a shallow intersection angle between the cut and rings.
Plainsawn lumber has several advantages when it comes to exposing attractive wood grain. By cutting slices near the outer edges of the log, plain sawing produces boards with unique, rustic flat grain patterns that are prized for aesthetic applications. It is also the most efficient way to mill a log, so plainsawn lumber is typically cheaper and more available than other lumber.
However, boards produced this way are prone to a type of uneven shrinkage called cupping. Cupped boards have long edges that turn upwards, making the piece appear trough-like and severely reducing its usability.
Quarter Sawing
Quarter sawing is a more complex technique than plain sawing, but it results in finer lumber and is popular for making high-grade boards. In this method, the log is divided into quarters that are in turn cut along their lengths so that each slice intersects the growth rings at a nearly 90-degree angle. When looking at the circular end of a log, this would correspond to the zones near the midpoint.
Because quarter sawing involves cuts that intersect growth rings at nearly 90 degrees, the spacing and thickness of the rings are directly transferred to the lines on the sawn face. Therefore, a log with uniform internal grain will produce a simple straight grain pattern of thin parallel lines on quartersawn lumber.
Quarter-sawn wood grain has certain advantages when compared to wood produced by other sawing methods. According to the USDA Forest Product Laboratory's Wood Handbook, quarter-sawn lumber does not shrink or swell as easily as plainsawn lumber. It is also ideal for producing several special types of wood grain.
In white and red oak wood, quarter sawing often exposes rays - wood cells that run horizontally from the inside of the tree towards the bark - on the cut surface of the lumber. The result is a unique pattern of slightly wavy ribbons or streaks in the exposed surface wood grain.
According to the Wood Database, this sawing method is also the best way to produce the famous curly pattern commonly found in maple wood. The prized shimmering wavy pattern is either diminished or altogether missing in flat-sawn wood from the same section of the trunk.
However, quarter sawing is a more wasteful process than flat sawing, so this type of lumber is more expensive and harder to find. It also tends to produce simple straight grain with little character when utilized on wood species that do not have special features like rays or curl.
Rift Sawing
Rift sawing is a rare method that is often confused with quarter sawing, but is actually a different process. As defined by the Architectural Woodwork Institute's Architectural Woodworking Standards, rift-sawn lumber is produced from cuts that intersect growth rings at an angle of 30 to 60 degrees. When looking at the circular end of a log, this would correspond the the zones between the top and midpoint.
Rift-sawn lumber can be thought of as a compromise between plain sawing and quarter sawing - the process is moderately efficient and produces grain patterns of moderate character. Due to the rarity of the method, however, this type of lumber can be difficult to find.
Rift sawing tends to produce straight grain in the same manner that quarter sawing does. Due to its intermediate intersection angle with the growth rings, rift-sawn lumber may exhibit somewhat wider lines and spacing than quarter-sawn grain. However, it generally still retains the straight grain pattern of evenly spaced parallel lines.
Conclusion
Wood grain patterns can be a complex topic, but understanding them is crucial to creating just the right look and feel in a project. Not only is the species important, but the way it is processed is crucial as well. Next time you've got grain on the brain, be sure to browse North Castle Hardwoods' excellent selection of quality plain, quarter, and rift-sawn species to find exactly what you need.
Burls, knots, medullary rays, annual growth rings, grains in the lumber such as wavy grain and cross grain, variations in the coloring matter irregularly distributed in the wood, or other distortion formed in the tree either from injury or the hazards of nature, form different patterns or figures in wood. The beauty of these figures or patterns may be greatly enhanced by the various methods of cutting the lumber from the log as previously explained. Some semblance of pattern or figure is found in all kinds of wood. In some woods the figure is very pronounced and strikingly variegated while in other woods it is obscure and rather difficult to identify. No two human beings are absolutely identical. Twins appear alike but there is usually some distinguishing characteristic. Similarly, no two pieces of wood are exactly alike or have exactly the same figure; there are differences in color, figure, texture and other physical properties. There follows a description and illustration of the most important grains and figures found in wood:
1. Even grain (Page 23) is found in lumber in which the contrast between “springwood” and “summerwood” is small and rather difficult to identify. The annual rings are quite uniform in width and the wood elements are parallel to the pith, such as in Birch, Maple, White Pine or Spruce. White Pine has a very even grain which makes it very desirable for pattern making.
2. Uneven grain is a term applied to lumber having a wide “summerwood,” and the growth rings are variable, wavy, and irregular such as Chestnut, Hackberry, and Osage-orange. The American Chestnut specimen shown on page 23 not only shows the uneven grain but emphasizes the attractive growth rings when cut at an angle of about 45°.
3. Straight grain applies to lumber in which the fibers are straight and parallel to the center or pith of the log, such as Pine, Fir, Redwood, Baldcypress and White Cedar. The straight grain of the Grand Fir shown on page 23 stands out prominently because of the resin ducts in the growth rings.
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4. Coarse grain (Page 24) applies to woods cut from rapidly growing trees. Where the pores are large and the annual growth rings are wide and conspicuous, the wood is called “coarse-grained” or “coarse textured" such as Ash, Sumac and Oak.
5. Close grain usually occurs in woods cut from slowly growing trees. Where the pores are small or closely spaced and the annual growth rings are narrow and inconspicuous, the wood is called “close-grained” or “fine-textured" such as Sugar Maple, Beech, Sycamore, Black Cherry, American Holly, Yellow Birch or Magnolia. A very good example of close grain is the American Holly shown on page 24.
6. Edge grain. “Edge grain” or “vertical grain” is obtained when lumber is sawed parallel to the center or pith of the log and approximately at right angles to the growth rings, the rings being 45º or more to the surface of the cut. This type of lumber is used to a large extent for flooring to provide strength and long wear. The edge grain may be easily distinguished in a considerable number of our woods but none perhaps more outstanding than the Baldy cypress, shown on page 24.
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7. Flat grain. “Flat grain” is obtained when lumber is sawed parallel to the center or pith of the log but tangent to the growth rings, the rings being less than 45º to the surface of the cut. The flat grain is doubtless the most common figure, best displayed in large wide boards. However, the small specimen of Yellow Birch shown on page 25 is a good example.
8. Spiral grain is a type of cross-grain and applies to lumber in which the fibers interweave and take a spiral or twisted direction, which may be either left-handed or right-handed, the latter being the most common. This grain is quite common in larch and horse chestnut wood. The wide growth rings of the Northern Catalpa shown on page 25 bring out clearly the spiral effect.
9. Diagonal grain is also a type of cross grain, and is not a natural phenomenon in the tree. It is obtained by the method of cutting the log into lumber, usually through poor milling practice, or in cutting crooked logs, where the cut is not made parallel to the fibers. When straight grain logs are not cut parallel with the fibers, a diagonal grain is obtained. The diagonal grain in the Black Walnut specimen shown on page 25 is made by cutting a straight grain board diagonally.
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10. Interlocked or cross grain is found in some lumber in which the spiral fibers of the annual growth tend to grow in opposite directions. Some species have a more or less pronounced interlocked or cross-grain in a considerable proportion of trees, such as Winged Elm and to a certain extent in the Gums, Beech and Sycamore. The quarter-sawed American Sycamore shown on page 26 is a good example of the interlocked or cross-grain.
11. Silver grain. (Page 26) In quarter-sawed Oak and Sycamore lumber where the medullary rays are large and look like “flecks” or “flakes” the wood is called “silver grain.” When such lumber is cut so that the large rays appear at nearly right-angles to the fibers, this silver grain is very prominent and attractive. In matching such pieces so that the silver grain of one piece is fitted so that the angle of the “flakes” is reversed, the figure is called a “herring bone.”
12. Stripe or ribbon figure is found in quarter-sawed lumber having more or less an “interlocked or cross-grain” where the layers consist of alternating light and dark stripes, running lengthwise of the piece. Usually the grain runs alternately inward and out-ward. Not many American species produce this unusual grain. It is occasionally found in the Gums, Black Walnut, and a few other woods.
13. Blisterfigure is found in plain-sawed lumber or rotary-cut veneer and is produced by an uneven contour of the annual rings which have knoll-like elevations. This figure is not caused by blisters or pockets in the wood, but irregular growth. It is especially prized in the Maples, Birch and Yellow Poplar. The beautiful blister figure of the Sugar Maple is shown on page 26.
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14. Quilted figure (Page 27) somewhat resembles the blister figure except the blisters are larger and cover a greater area of the board. The tree trunk below the larger limbs of leaning trees is under great pressure which causes the fibers to form corrugations in the grain. When the log is cut tangentially, this beautiful quilted figure is obtained. This unusual and attractive figure is obtained in Maple and several other hardwoods.
15. Wang figure. When the fibers have a wavy or “wrinkling” arrangement a wavy figure is produced. This occurs most frequently at the base of the tree Where the roots join the stem, or immediately below the crotch where the limb extends from the trunk. It occurs in Birch, Maple, Redwood and infrequently in some other woods. The wavy figure of Sugar Maple shown on page 27 is especially pleasing.
16. Fiddle-backfigure. (Page 27) The figure commonly known as “fiddle-back” is an unusual and very beautiful figure caused by natural fluctuations due to local conditions or influences on growth producing fine regular waves or ripples. It is this figure which is extensively used for the back of violins. This figure is found principally in Sugar Maple and Mahogany and occasionally in other woods. When the log is cut radially the fiddle-back figure is most outstanding and attractive.
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17. Mottle figure. This is a very beautiful and outstanding figure formed when the fibers extend irregularly in short wavy configurations in variegated patterns. Several types of the mottle figure are produced when the grain of the wood is twisted or interwoven. It is frequently found in quarter-sawed boards and especially in Walnut butt veneers. The mottle figure of the Black Walnut is used extensively in cabinet work.
18. Snail figure.This very unusual figure is so named because of the resemblance of the fine curved lines to a snail pattern. It resembles a burl somewhat, but the snail figure is found in the trunk and stump of the tree rather than in the burl formation. The beauty of the figure is greatly enhanced by the careful cutting of the veneers. The snail figure is rather uncommon and usually confined to Black Walnut.
19. Finger Roll figure. As the name implies, this figure occurs when the fibers form a wavy pattern of finger size which extend across the grain or cross-figure, principally found in radially cut lumber. It is frequently found in fiddle-back, raindrop and mottle figures. The finger roll figure in the Sugar Maple is conspicuous - shown on page 28.
20. Bird’s-Eye figure. (Page 28) This beautiful figure is a phenomenon in wood the cause of which is not definitely known. Bird’s-eyes are conical indentations or tiny knots in the grain of the wood, usually extending from near the center of the log to the outside layer and discernible also in the bark. Some trees are found, however, in which the bird’s-eyes extend only a few inches from the outer portion of the log. The fibers are greatly distorted into what appears as small pimples or depressions in the annual rings. When once formed, the annual growth rings usually follow the same contour for years. When these depressions or pimples are cut through crosswise the figure suggests a bird’s eye. The birds eye is most frequently found in a small percentage of Sugar Maple, but may also be found in other hardwoods such as Soft Maple, White Ash and Yellow Birch. A beautiful Juniper bird’s-eye log, about 12 inches in diameter, was found in the Rocky Mountains. Such trees are very rare, however.
21. Curly figure. The curly effect appears in wood in which the fibers form waves or undulations, generally surrounding knots in the tree trunk, the distorted tissues forming this outstanding figure. It is quite common in Yellow Birch and Sugar Maple, although it is frequently found in many other hardwoods. It is seldom found in softwoods. Occasionally a very unusual curly grain is found, which because of its strange figure is called “Landscape grain.” While the curly grain is generally identified with Yellow Birch and Sugar Maple, it is occasionally found in Long-leaf Pine such as shown on page 28.
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22. Burl. A burl is a wart-like abnormal growth on the outside layer of a tree trunk, usually resulting from an injury to the tree. A burl contains the dark pith of a large number of buds which have not developed, and the fibers are very distorted, irregular and do not run in any particular direction. This phenomenon may occur in any kind of tree. The burls of Black Walnut, Maple, California Laurel, Redwood, Black Cherry, Ash and Birch are exceedingly beautiful and are highly prized for cutting veneers used in the manufacturing of fine furniture or expensive novelties. Many kinds of our trees provide burls which are most attractive. The Black Ash burl shown on page 29 is an excellent specimen.
23. Swirl. (Page 29) Where the fibers are considerably contorted in barrel-shaped bulges in the log, a veneer cut produces a figure of curly grain or “swirl.” It is greatly mottled and burl-like. This conspicuous and unique figure is also greatly prized for the manufacture of furniture, and is found in a considerable number of hardwoods.
24. Knots. (Page 29) A knot is the base of a limb usually originating at or near the center of the tree. Knots due to suckers or sprouts originate near the outside of the tree trunk. They usually slope upward. Knots give a distinct figure and are attractive in some woods, such as in Eastern Red Cedar, for the manufacture of cedar chests, in pine or cedar called “Knotty Pine” or “Knotty Cedar,” used for interiors of homes and offices. The knots, however, must be solid or “tight.”
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25. Crotch figure is obtained from the tree where the large limbs join the main stem, or from the main forks of the larger limbs.It is usually Y-shaped, and is a striking figure. The most conspicuous types of it are generally found in Black Walnut. The crotch figure is rather common but nonetheless attractive in the Black Walnut specimen shown on page 30.
26. Feather Crotch figure (Page 30) is one in which the fiber alignment fans out giving the appearance of a cluster of feathers, caused by the twisted and crushed grain of the crotch-wood. The outside slices of the crotch generally produce a swirl figure changing to the feather or regular crotch figures as the slices approach the center of the piece.
27. Moonshine Crotch is a swirl figure in the crotch. The moonshine figure is very uncommon.
28. Stump-wood figure is obtained from the bell-shaped tree base immediately above the roots. The suppressed and twisted fibers in this area of the stem form an attractive figure called stump-wood figure. The stump-wood figure of Black Walnut is not particularly attractive although it is used with good results in combination with other figures.
29. Pigment figure is the name given to the distinctive figure caused by the irregular distribution of the color pigment in the wood, resulting in streaks or patches that are darker than the surrounding wood. Pigment-figured red gum is an example of this figure. The pigment figure of the Sweet Gum shown on page 30. displays prominently the color contrast in this wood.
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