318 ENGINEERING ON THE FARM 



the application of a thick coat of shellac. The shellac effec- 

 tually seals the knot surface, and little trouble is experienced 

 with the pitch coming through. A priming coat should be 

 largely raw oil. A little lead and coloring matter may be 

 added, also a small quantity of turpentine. If, however, 

 the surface is dry and the best work is desired, the turpentine 

 should be left out. A week, at least, should elapse before 

 the first coat is applied. This coat should approach the 

 desired color of the final finish. The first coat must be 

 allowed to dry thoroughly before the second is applied. It 

 is a good practice in painting to put on plenty of brush and 

 a thin coat of paint. It is better to wear out several brushes 

 than to apply thick, heavy coats of paint. Thick coats 

 creep and do not dry properly. The result is a rough, 

 imperfectly bonded coat. 



Interior painting. There is no marked difference between 

 the treatment of interior and exterior surfaces. The finished 

 job should be a little more neatly and carefully done. This 

 applies especially to the last coat, which should be spread 

 smoothly and evenly. A precaution necessary on interior 

 work is to putty all nail holes after the priming coat has 

 been applied. It is impractical to putty before, because 

 the oil of the putty is quickly extracted by the wood, with 

 the result that the putty shrinks and drops out. If the holes 

 are puttied after the priming coat, the filling material has 

 an opportunity to harden before it loses any of its oil. As 

 white-lead paint turns yellow, interior white paint should 

 be of zinc oxide, or a last coat of zinc paint applied as a 

 protective finish. Enamel paint, as used for interior finish, 

 is a paint in which varnish is used as a vehicle instead of oil. 

 A thorough job of enamel painting calls for four to seven 

 coats, not more than the last two being enamel paint, each 

 coat thoroughly sanded after drying. 



Varnishing. Close-grain woods should receive as a first 

 coat a primer of glue or very thin shellac. Open woods 

 should receive a filler of the paste variety. This paste filler 



