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Grains and Figures in Wood

Introduction

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:

Grain Types

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.

page 23
Page 23


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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Page 24


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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Page 25


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.

Page 26
Page 26


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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Page 27


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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Page 28


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.”

Page 29
Page 29


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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Page 30

Bibliography


  • Shelley E. Schoonover (American Woods) 1951 (Watling & Co. ) Santa Monica, CA 

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Page last modified on Sunday October 7, 2018 09:03:57 PDT by admin.