i6 



HARDWOOD RECORD 



Janaary 10, ISIT 



growth ring round the trunk, but crosses and reorosses several rings, 

 in a wavy or irregular line. Sometimes there is much thicker sap- 

 wood on one side of a tree trunk than on the other. Occasionally the 

 heartwood surrounds and includes jiatehes of sapwood which in cross- 

 section resemble islands surrounded by darker areas. This phenome- 

 non is very common in the Virginia red cedar and other junipers, and 

 is not infrequent in mesquite, Texas ebony, and some other woods. 



Ill sawing logs of irregular and fantastically-shaped heartwood, 

 isolated patches of sap are liable to appear here and there on the sur- 

 faces of boards, to puzzle the grader if not to annoy the user. Such 

 patches of sap, surrounded by heartwood, may often be seen on cedar 

 chests and shirtwaist boxes. In those instances, however, the patches 

 add to rather than detract from the value of the article, for they 

 afford contrast in color and grain, which in that case is most desired. 

 Isolated areas of sapwood are occasionally seen, also, in musical 

 instruments and small articles of furniture, which are usuEflly made 

 in local shops, of troiJical or subtropical hardwoods that have irregu- 

 larly-formed heartwood. Wlicu skillfully worked, such sap patches 

 look like inlay of differ- 

 ently colored wood and 

 may be very artistic. 



The true line of sepa 

 ration between heart and 

 sap is not always visible. 

 Wlien the wood of a grow- 

 ing tree dies, it becomes 

 heart very soon, but some 

 years may pass before it 

 takes on the characteristic 

 darker color, and some- 

 times it never does. It 

 frequently happens that a 

 log has more heart than 

 appears to the eye. For 

 that reason, grading rules 

 which hold sap as a de- 

 fect cannot always be ap- 

 plied, because the grader, 

 judging by appearances 

 only, may not be able to 

 draw the line exactly. 

 However, contrast in color 

 between the two kinds of 

 wood is the only practical 

 guide for the grader. He 

 cannot be expected to ex- 

 amine the wood with a 

 microscope to separate the heartwood from the sap. 



Relatively, the heartwood increases and the sap diminishes with 

 the age of trees. However, some of our best trees are half sap until 

 well along toward maturity, such as basswood, hickory, ash, beech, 

 and some of the yellow pines. The proportion of sap to heart in a 

 number of trees at maturity is given as follows in Samuel J. Record "s 

 "Economic Woods of the United States": 



RED GUM IS ANOTHER WOOD WHICH LENDS ITSELF WELL IN INTERIORS 

 TO THE JUDICIOUS USE OF SAP EDGES 



Percent of 

 f^prcics Sapwood 



Ijmiilnaf pine 40 



Ciilian pine 50 



liolilolly pine 5.5 



Basswood 65 



Perecnt of 



Impedes Sapwood 



Black locust 12 



White oalc 20 



Yellow poplar 2(1 



Virginia red cedar 25 



White pine 30 



If these species may be taken as representative, they show that the 

 average forest is more than one-third sapwood. No specific period 

 of time can be named, in which the change from sap to heart in a 

 particular layer of wood takes place. It may be anywhere from five 

 to fifty years, or even more. That is, it may remain sap that long 

 before it changes. 



Difference m Value 



^apwood is imperfect wood. It must die and become heart in order 

 to become perfect. Wlien freshly cut, sapwood generally contains" 

 more water than heartwood, and it is usually weaker. It is also less 

 dur.able when exposed to the agents of decay. Its color, likewise, is 



commonly less desirable than that of heart. There are exceptions to 

 all of tliese statements, so far as commercial value is concei-ned, for 

 there are woods the sap of which is worth more than the heart. 

 Hickory is one of these, ash another, dogwood and persimmon are 

 others. Hickory sapwood, which is white, is preferred to heart, which 

 is red, for handles and spokes, despite the fact that government 

 reports have tried to place the red on the same basis as the wliite. 

 The testing machines seem to jirove that the heart is as strong as the 

 sap, but popular belief, or prejudice, still favors hickory's white sap- 

 wood for most purposes. 



Popular opinion in favor of the sapwood of ash is not quite so 

 strong as that which favors sap hickory; but it is commonly believed 

 that long handles for rakes, forks, and shovels are better if of ash 

 sapwood. 



In view of the estimate that about thirty-five percent of the wood 

 in American forests is sapwood, it becomes highly important that 

 special pains be taken to put it to use where possible. There is a 

 growing tendency to do this, and the sap of some kinds of wood is 



winning itself a place in 

 the country's industries. 

 Gum supplies an exam- 

 ple. The plain sap is 

 stained, and otherwise 

 finished in imitation of 

 costly cabinet woods, 

 while figured sap has 

 proved its worth in built- 

 up tops and panels which 

 pass muster anywhere. 

 The developing of white 

 enamel in furniture and 

 finish has opened a new 

 field which the gum pro- 

 ducers are taking advan- 

 tage of. In a cruder 

 form it has earned a 

 I)rominent position for 

 many humbler uses. 



American black walnut 

 gives another illustration 

 of the profitable use of 

 sapwood. Former usage 

 condemned this part of 

 the log. In fact, grading 

 rules still provide that it 

 lie considered a defect. 

 But producers and eon- 

 sumei-s alike refuse to recognize the logic of this provision and buy 

 and sell on their own specifleations. The lumber is liandled through 

 steaming chamljers to bring up the color of tlie sap and the process 

 is completed with satisfaction to everybody concerned in the factory 

 finishing room. 



Makers of shuttles want the sapwood of dogTvood and persimmon 

 but no heartwood. Yet the heart of persimmon is valuable for some 

 purposes. The ebony of commerce comes from the heart of certain 

 species of persimmon, which are not native of the United States; 

 but the heart of dogwood is never large enough to be valuable. 



The manufacturer of spools from paper birch wants no heartwood. 

 He sells that to brush back makers who want the colored wood. 



Decay and Preservation 



In exposed situations sapwood decays more readily than heart. 

 That rule seems to be universal, and the reason for it doubtless is 

 that in this portion of the tree are found more abundantly the 

 starches, sugars, and other substances on which the organisms feed 

 which produce decay. 



In some regions worms and other boring insects destroy the sap- 

 wood of timber without penetrating the heartwood very far. In 

 forests along the Rio Grande it is not unusual to see dead tree trunks, 

 erect or prostrate, with all the sap eaten away and the heart unin- 



