May 25, 1917 



Figure Due to Twisted Grain 



Ho Maxwell 



Editor's Note 



There are a few well known figures in wood which a re Jmost wholly dependent upon direction of gral 



and the angle at which the saw or knife cuts the grain. Such are birdseye. wavy, curly, and smoky figures. 



These differ among themselves, but the cause that prod uces all of them is a peculiar reflection of light from diS' 



torted wood fiber. These figures are Quite common in cer tain woods, like maple, walnut, ash and redwood, and less 



common with others. The causes of the distortion of gr ain, which produces the figures, is known In some cases, 



while in others there is considerable doubt and contrary o pinion. 



AitTICLE NINE 



Several figures in wood are due to distortion of grain. These figures 

 are known as birdseye, curly, cloudy, smoky, and some others. They 

 are largely independent of growth rings, medullary rays, and abnor- 

 mal deposits of coloring matter. The grain of the wood, because of 

 some accident, peculiarity, or freak, does not lie in a normal position 

 and for that reason reflects in an unusual way the light that falls upon 

 it and thus produces the figure. 



The word ' ' grain ' ' as applied to wood is here used in a limited 

 sense. It does not mean rings, it does not mean pores, it does not mean 

 rays, but it means fibers, those elements of wood which ordinarily run 

 up and down the tree trunk. If they are visible, they look like minute 

 splinters. They run up and down in "straight grained" wood; they 

 cross and interlace in "cross-grained" wood; 

 and in ' ' twisted " or " curly ' ' grained wood 

 they take a spiral direction. .This is the grain 

 which is concerned in several common figures 

 valued by woodworkers. If they run straight 

 up and down, they produce no figure; but if 

 they bend to one side or the other, they may 

 interrupt the normal reflection of light from 

 the surface, and thus produce figures. 



The Birdseye Efpect 



The most important and familiar figure of 

 this class is known as birdseye, wliich is a de- 

 scriptive term. It is not necessarily a maple 

 figure, for it is found in a number of other 

 woods and probably it occurs occasionally in 

 every one. It is best known in maple because 

 this is an abundant timber and in wide use. 

 Considered tree by tree, birdseye is as fre- 

 quent in some other species as in maple, and in 

 the silverbell tree it is much more abundant. 



Peculiar notions and erroneous opinions pre- 

 vail as to the cause of birdseye in wood, and 

 these are not confined to ignorant people. 

 Some of them are found in books by writers of ability. Nearly 

 two hundred years ago a Virginian writer who said many inter- 

 esting things about geography and natural history, stated that birds- 

 eye maple owed its existence to holes pecked in the bark by parra- 

 keets (a diminutive parrot then plentiful in Virginia but now extinct 

 there) ; although this bird 's beak was hooked and it could not have 

 peeked a hole through maple bark if its life had depended upon it. 



The notion is quite common that sapsuckers are responsible for the 

 birdseye figure. These birds peck numerous holes in maple bark, 

 partly to drink the sap that colleet-s there, and partly to catch flies 

 attracted by the sweetness. The sapsuctker perforates the bark o-f apple 

 trees more thoroughly than maple, yet birdseye applewood is not often 

 mentioned. 



Some woodsmen attribute birdseye figure to the action of frost, but 

 without attempting to explain the modus operandi. Others find the 

 cause in lightning; but explanations are not offered. 



There should be no question as to the cause of birdseye figure. 

 Adventitious buds are held to be responsible. These buds are hidden 

 beneath the bark and are unable to force their way through it. There 

 is no definite information as to the length of time the buds remain 

 alive, but there is no doubt that they often originate while the trunk 

 is small and remain a disturbing factor until the tree attains large 



BURL OF BLACK WALNUT 



Masses of suppressed buds cause the excres- 

 cense and produce figure by distorting the 

 grain. 



size. Thus a particular birdseye that occurs on the surface of a large 

 trunk may often be traced, by removing slice after slice of the wood, 

 nearly to the heart of the tree. The same cause continues to dupli- 

 cate a particular birdseye figure for a hundred years or more, whether 

 it is due to one bud surviving so long or to bud succeeding bud in the 

 same place year after year, and always remaining beneath the bark. 

 Huron Smith, former dendrologist of the Field Museum, Chicago, 

 dissected the buds from birdseye and burls, as a surgeon would dissect 

 out a nerve or vein from the tissues of a muscle. 



Anyone with a birdseye log and a few tools can perform interesting 

 operations. Cut down through the center of a birdseye figure with a 

 saw, from the surface toward the heart, and polish smooth the ex- 

 posed surface. A cross section of the figure is thus revealed, and the 

 bending aside and distortion of the fibers are 

 shown, year by year, each season's being a 

 pretty fair replica of what grew the year be- 

 fore. 



The Deflected Fibers 



In making such a study a magnifying glass 

 wUl assist in observing several interesting 

 things. The fibers are forced aside to pass 

 round the obstacle. They bend this way and 

 tliat, but succeed in passing, and in so doing 

 tliey reflect the light from different directions, 

 and that produces the figure effect. 



The birdseye of sUverbeU is at least as ar- 

 tistic as that of maple. It is composed of 

 more finely -colored wood; but it has not usu- 

 ally been found satisfactory, because the cen- 

 ters of the eyes are liable to drop out, when 

 the wood is sliced as veneers. 



Yellow poplars in the sappling stage, from 

 six to ten inches in diameter, are liable to have 

 birdseye wood, but it is not attractive, and 

 the trunks apparently overcome the distor- 

 tions as size increases. Where pulpwood cut- 

 ters are operating in stands of sappling yellow poplars, and peeling 

 the trunks, the frequency with which specimens are seen with sur- 

 faces embossed with small, sharp-pointed protuberances, shows the 

 prevalence of birdseye growth in this species. 



The wood forming a birdseye does not differ much in color from that 

 wholly outside. The diflferenee is in luster. 



The Buel Figure 



The burl in wood might be described as a compound birdseye. That 

 definition would need to be modified in some cases, for it is not always 

 easy to distinguish between a burl and other kinds of excrescences. 

 There is a pretty large family of knobs, lumps, knots and abnormal 

 growths occurring on the trunks of trees, and between some of them 

 there is no close relationship either in origin or structure. All are 

 probably due to obstructions of natural growth, and to the tree's 

 efforts to heal a wound, occlude an irritant, or expel an enemy. They 

 may be caused by burns, bruises, cynips, and buds beneath the bark. 



It is only the burl caused by adventitious buds that calls for con- 

 sideration in discussing figured woods. Such is the walnut, ash, and 

 redwood burl, the three most important in this country from the 

 woodworkers' standpoint. Veneers sliced across such burls are often 

 very fine. There are clusters of multitudes of birdseyes, intertwined 



-18— 



