PRACTICAL TREE SURGERY 



733 



tensively used with good results. 

 Although one coating of this mix- 

 ture may at times be sufficient, it 

 is always safer to follow it with 

 a heavy coat of coal tar. 



A good grade of lead paint can 

 he substituted for the tar, if de- 

 sired, although it is not generally 

 considered as satisfactory; or 

 grafting wax may serve satisfac- 

 torily for small surfaces. Asphalt 

 and \arious j)rei)arations contain- 

 ing asphalt are excellent water- 

 j)roof coverings and would doubt- 

 less be more generally used were 



No. 1. — It would be bet- 

 ter to make these cavi- 

 ties oval and pointed 

 instead of square or 

 round. 



No. 3.— Injury shown in 

 No. 2 excavated and 

 ready for tarring prior 

 to filling. 



No. 2. — An old in- 

 jury caused by 

 horses gnawing 

 the bark. 



Plate Xo. 3. — Long Cavities Excavated Through Sev- 

 ER.\L Openings and Short Cavity Excavated Through 

 One Opening. 



The entire shellacked and creosoted sur- 

 face must hnally be waterproofed by 

 painting it with heavy coal tar. A 

 single application of a mixture of creo- 

 sote and coal tar ( about one-fourth or 

 one-third creosote) has been quite ex- 



it not necessary to apply them 

 hot. A good and possibly 

 more ])ermanent method of 

 treating the scars is to char 

 the surface slightly with a 

 ,'-asoline or alcohol blast torch 

 and then cover the hot sur- 

 face with heavy tar or hot 

 as])halt. .Although heat is an 

 excellent sterilizing agent, it 

 docs not penetrate so well as 

 creosote and it kills back the 

 cambium to a greater extent. 

 Permanent waterproofing 

 can be secured only when the 

 treated surfaces are watched 

 from year to year and recoated when 

 any tendency to crack or peel is ob- 

 served. This is an imi)ortant step, 

 which is almost invariably neglected 

 by tree owners and tree surgeons. 



