Wood Preserving Department 



The Modern .Ipplicatioii nf Wood I'rcscriiiu/ Methods — Furious Treatments mid the Uses of Treated Woods 



By E. a. Sterling 



[111 tliis department each month will be given the hest information regarding all phases of wood treatment by preservatives 

 and the uses and values of treated woods, this having liecome an essential feature of conservation. The Editor will welcome 

 any inquiries.] 



THE universal use of wood makes the modern 

 practice of preser\'iiig it against decay of wide 

 interest, 'i'he saving which is eft'ected, and the 

 extension of the use of wood because it can be made 

 jiermanent. cmicerns the consumer, the lumber producer, 

 and the wood preserving interests on common ground. 



The decay of timber has been a problem since time 

 immemorial, yet \V(.)od so far surpasses all nlher struc- 

 tural materials in workaljle i|ualities, availaliilitw lieauty 

 and ci.invenience that it has held its own through all the 

 years. Under modern competition with other materials 

 it still retains the leading place, ami by proper preserva- 

 tive treatment as now develo]ie<l the renewals necessi- 

 tated liv decay can be greatly reduced or eliminated. 

 I'ernianence and improved service become a matter of 

 knowledge. Information on the subject should lie ex- 

 tended so that treatment can be ajiplied where it is 

 economical or otherwise ad\isable. 



In this country the extensive commercial applicatiini 

 of wood preserving methods is a twentieth century 

 development. It is true that the first plants were built 

 nearly iorty \ears ago and crude treatment applied even 

 earlier: yet only during the last fifteen years lias there 

 been rapid advancement. In Europe wood preserxation 

 has been an accepted practice for three-quarters of a 

 centurv. with the recorded experimental use of many 

 preservatives and processes extending back to Ki.'i';'. 

 Even in the diiu ages of l{gyptian su])remacy, it is 

 apparent that ways and means had been found for pre- 

 serving animal and vegetable tissues indefinitely ; while 

 during the early Greek and Roiuan civilization oils were 

 ,'ipplied to preserve their statues and t.iridges. 



The modern a])i)lication of wood preserxation depends 

 on the economic advantages and on knowledge of the 

 ])ossibilities and methods. During the years of rapid 

 industrial expansion and of cheap and abundant supplies 

 f/f lumber it was cheaper to renew the wood which 

 decayed than to incur the greater initial expense of mak- 

 ing it |iermanent. These conditions no longer hold, 

 hence the adoption of wood-preserving jirocesses, first 

 by railroads for crossties and bridge timbers ; later for 

 a great variety of construction timljers which are subject 

 to decav. The next step is to the home builder .iinl retail 

 trade. 



Despite the fact that several luindreil different ma- 

 terials have lieen tried and advocated for jireserving 



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wood, the cheapest and most elTective in use today have 

 been known and used for many years. These are coal 

 tar creosote and zinc chloride, each having been brought 

 to us from Europe. Strangely, both were invented or 

 proposed in England in the same year — ISoS. New pre- 

 servatives are continually being produced and promoted, 

 and while some of them have luerit. the two old stand- 

 ards reiuain sujjreiue in point of consumption and 

 general acceptance. The test of time is the essential 

 proof of efficiency, and other [ireservatixes may ulti- 

 mately make good. To merely prevent or defer decay 

 is not enough; the ideal preserxative luust be permanent, 

 penetrate the wood readih'. and not be too costly. 



The nature of decay is understood by scientists, but is 

 not of general knowledge by the public or even by every- 

 one interested in the wood-preserving business. As 

 applied to wood decax' is caused by vegetable organisms 

 known as fungi. These propagate by means of micro- 

 scojiic spores, which are ei|uivalent to the seeds of 

 plants. ISeing produced in enormous numliers and 

 blown about b\ tlie wind, they are present everywhere. 

 When the\' find lodgement on wood they develop a 

 growth of microsco|iic threads which ])enetrate the 



tissues of the w 1 and cause disintegration. After a 



period of growth they produce fruiting organisms which 

 constitute the common fungus growth seen on decayed 

 wood. 



In order to develoj), the fungi must have moisture, 

 favorable temperature, air sti|>ply. and food. The latter 

 is furnished by the wood itself and the other factors 

 are jiresent in practically all outdoor conditions. Pre- 

 servatives i)revent the development of the organisms of 

 decay through the douljle function of being antiseptic 

 or toxic and killing or poist)ning the spores, and by at 

 least partial elimination of moisture. The antise[)tic 

 feature is probably the most important and while inert 

 oils, which t(] an extent waterjiroof the wood, will pre- 

 vent decay for a time, they are not certain or permanent 

 iij their action. Coal tar creosote is both antiseptic and 

 moisture excluding to a marked degree. It also has the 

 further advantage of ]ieriiianence. Zinc chloride is 

 effective mainly through its poisoning action to low 

 forms of vegetable growth and from our present knowl- 

 edge is of greatest efficiency in regions of low rainfall or 

 in dry situations. 



Preservatives are a[ij)lied to wood in several diti'erent 

 ways, the more common forms of treatment being pres 



