■Tilly 10. 1(117 



Figures Due to Pigments 



Hu Maxwell 



' Editor's Note 



If "the weak things of the earth are chosen to coutCnnil the mighty," sapstain, as the lumber- 

 man knows it in his yarrl. ranks high in the list of such weak things. It has not been so many 

 years since sapstain in lumber was looked upon much as people used to look upon plagues among 

 men — as a sort of judgment sent by heaven, and therefore beyond human control. That opinion has 

 now passed awav. The cause of sapstain and its method of attack are now well understood, and the 

 principal concern is to find remedies or means of prevention. Success is rewarding research in that 

 direction : and, though there is no reason to expect that the agencies which produce the stain can be 

 eradicated, progress has been made In devising means of warding off attacks of the insidious pest. 



ARTICLE ELEVEN 



A certain kind of discoloration of lumber is known as sapstain, 

 and a common sort of sapstain is called ' ' bluing. " It is so named 

 from the bluish tinge which characterizes it. No part of the United 

 States where lumbering is carried on is wholly free from sapstain; 

 but it is much worse in damp, warm regions than in those dry and 

 cool. The stain or discoloration cannot be washed off, as soot or 

 other surface deposit might be. It is entirely different from the 

 discoloration known as weathering. Sapstain is at its worst on new 

 lumber, while weathering does not attain its maximum until the 

 lumber has aged considerably. 



The processes by which wood becomes sapstained cease wholly 

 when the temjierature falls below freezing and do not again be- 



s r MAXv/eu. 

 DIFFERENT TYPES OF SPOHES 

 1 — .\lgae spores, swim in water; 2 — Scouring rush spores, move b.v 

 kicking; 3 — Pine spores (pollen), fly with wings; 4 — Fungus (sapstain) 

 spores, float in air. 



come active until after ice and frost disappear. Summer is, there- 

 fore, the season of greatest loss from this stain. Damage may be 

 excessive in lumber yards and is considerable whenever green lum- 

 ber is exposed to the air during warm, damp weather. It is worst 

 in lumber yards because sapstain is contagious and affected mate- 

 rial passes the disease on to healthy stock. 



Lumber falls in value after being stained. It may deteriorate 

 from fifty cents to two dollars per thousand feet. It has been esti- 

 mated that one-fourth of the whole sawmill output of the United 

 States suffers from sapstain, and that the annual loss from that 

 source in this country is not under .$8,000,000. Part of this decrease 

 in value is due to the unsightly appearance of the lumber. It looks 

 dirty, but the discoloration cannot be wholly removed bj' passing 

 the boards through a planer and shaving the surface off. The stain 

 is not confined to the outside, but goes deep. A shaving cut from the 

 surface uncovers similar stain deeper down. However, the principal 

 decrease in value is not due- so much to the appearance of the 

 affected wood as to the very general belief that such wood is not so 

 sound as it was before the discoloration. Consequently, it does not 

 command the price of unstained lumber. 



The prejudice against stained lumber, under the assumption that 

 it has been weakened or softened, may be justified to a small extent, 

 but the difference in hardness and strength before and after is not 

 tisuall.v great. The government laboratory at Madison, Wis., proved 

 bv tests that heavily-stained shortleaf pine is slightly weaker, less 

 tough, and shows less surface hardness than the unstained; but in 

 longloaf pine, when slightly stained, the difference in strength, 

 toughness, and hardness, between stained and unstained boards, is 

 too slight to be noticed. Hermann von Schrenk's investigation 

 of the bluing of the yellow pine of the Black Hills region showed 

 that, under some tests, particulnrly "sj.litting, the stained wood was 

 stronger than the unstained. 



—18— 



Less Falls on Low Gr.\de Lumber 

 The largest loss on account of sapstain falls on low grade lumber, 

 for two reasons. First, such lumber is largely sapwood and is 

 peculiarly liable on that account to be attacked by the stain. Heart- 

 wood is not attacked. Second, low-grade lumber is seldom passed 

 through dry kilns but is left in yards to season in the open air, and 

 during the early part of the seasoning process such lumber is almost 

 certain to be attacked by stain, if the weather is not too cold. 



One of the largest users of low-grade lumber is the box maker. 

 He may not object to the stained wood on account of its supposed 

 loss of strength, but he objects to the off-color. Many kinds of 

 boxes are printed or stenciled to give the name of a manufacturer 

 or the address of a purchaser, and stained wood does not display 

 lettering to advantage. It is too dark. The box maker who has 

 such lumber on hand must use it for boxes which do not call for 

 stenciling, and this restricted use for the lumber is reflected in the 

 price which the buyer is willing to pay for it. 



The Agents of S.\pstain 



The cause of sapstain in lumber is well known to be a fungus, or 

 rather funguses of different species; but there is not entire agree- 

 ment as to the lesser details of the phenomenon. The theory that 

 some of the stain is due to chemical action, at least as a secondary 

 cause, has advocates, and they may be correct. But it is no longer 

 open to question that most of the stain is due to the growth of 

 fungus upon or beneath the surface of the wood. 



Fungus is a plant of low order which lives, for the most part, on 

 dead organic matter, either of animal or vegetable origin. There are 

 thousands of species. Some are well known, such as toadstools and 



^ F- M/\XWE.l.l- 



A SAPSTAINED PL.VNK 



The sapwood has been colored by fungus while the heartwond has escaped 

 discoloration because immune to attack. 



mushrooms; others are small and frequently wholly invisible to the 

 naked eye, unless accumulated in largo masses. The fungus that 

 proiluces sapstain in lumber is not visible without a lens, except in 

 mass. The individuals are of extreme smallness. 



Fungus of that kind is mostlj' roots, if the part beneath tjie sur- 

 face may properly be called roots. They are thread-like in form 

 and are known to botanists as mycelia. The mycelia of the sap- 

 .stain species strike into the wood and penetrate it in much the 

 same way as the roots of clover penetrate the soil. They are able 

 to do this, because wood is a porous substance, like a sponge, and 

 the fungus threads can penetrate from cavity to cavity with great 

 speed until the hollow spaces of the wood are filled with masses of 

 the threads. 



The minute thread tips have the power of boring holes through 

 the thin walls separating the wood cells, if they do not find open- 

 ings ready made, which is frequently the case. 



The fungus penetrates the wood cells in search of foo<l wliich 



