220 



SELLING LUMBER 



Blue Stain 

 Does Not 

 Affect 

 Strength 

 of Wood. 



Turpentining 

 Does Not 

 Affect 

 Strength 

 of Wood. 



Decay 

 Spreads 

 from Sap- 

 wood to 

 Heartwood 



hours produce new fruiting bodies which discharge more spores. 

 The so-called blue stain (which is in reality gray) is due to the 

 combination of color of the fungus threads and the color of the 

 wood fiber. The blue stain fungus grows only in the sapwood, 

 and is therefore frequently a good means of identifying which is 

 sapwood and which is heartwood. I know of no case where the 

 blue stain fungus has ever been found growing in heartwood. 

 The fungus does not attack the wood fiber, and blue stained sap- 

 wood is therefore just as strong as unstained sapwood. Numerous 

 tests made under my own direction by the United States Gov- 

 ernment and similar tests made in the German government testing 

 laboratories have demonstrated this beyond doubt. The only 

 defect which the blue stain fungus gives is in the matter of appear- 

 ance. In view of the fact, however, that its presence is frequently 

 highly undesirable, various schemes have developed for preventing 

 the growth of the blue stain fungus. The principal methods now 

 used consist in dipping freshly sawed lumber in various salt solu- 

 tions. The principal salts used are sodium carbonite (soda ash), 

 sodium bicarbonate (baking soda), sodium silicate (water glass), 

 and sodium fluoride. These salts are used in strengths varying 

 from 2 per cent to 5 per cent. The first two are principally used, 

 and where the work is efficiently done, they practically eliminate 

 blue stain. 



Speaking of the relation of the blue stain to strength, it may 

 not be out of place here to refer to the influence of turpentining 

 on the strength of yellow pine timber. Turpentining removes 

 the natural resin from the tree. Resin is an excreted product of 

 the pine tree and is produced in special canals. When the pine 

 tree is tapped, the resin contained in the sapwood exudes from 

 the wound. No resin is ever extracted from the heartwood during 

 turpentining operations. Exhaustive tests made under the aus- 

 pices of the United States Forest Service have shown conclusively 

 that there is no loss of strength due to turpentining operations. 



Coming now to the fungi which grow on sapwood, their num- 

 ber is legion and they produce every conceivable kind of rot or 

 decay, known popularly as sap rot, dry rot, wet rot, brown rot, 

 etc. These terms have little practical significance. As already 

 stated, the sapwood of all pines (and for that matter, of all tim- 

 bers) is very susceptible to the attack of fungi, and when so 

 attacked will rarely last more than a year or two. After the sap- 

 rotting fungus has obtained a foothold in the sapwood, in the 



