FARM MANAGEMENT 63 



Some pigments, however, have the property of hastening the 

 drying of linseed oil, and any other drier. The varnish-like film left 

 by linseed oil is for practical purposes insoluble in water. It is not, 

 however, impervious to water. But, if an oil paint is employed 

 that is, a mixture of pigment and linseed oil it will be found that 

 water does not penetrate through the film so rapidly as it does through 

 the linseed-oil film alone. Also the paint film is more resistant to 

 mechanical abrasion. While there is some difference of opinion 

 among experts as to the amount of pigment which should be used in 

 a paint, it is generally considered that the greater the amount of pig- 

 ment the more resistant the paint film is, provided all the particles 

 of pigment are thoroughly covered with the oil. It would appear, 

 therefore, that a film of oil, while it may seem to be homogeneous 

 even if examined under a high-power microscope, is really porous, 

 and by mixture of the oil with the pigment the pores are more or 

 less completely filled, thus making a more impervious film. In ad- 

 dition to the linseed oil and drier, paints frequently contain volatile 

 substances, such as turpentine and benzine. The addition of these is 

 largely for the purpose of thinning the paint to a better working con- 

 sistency, so that it can be spread in thin layers more easily. These 

 volatile substances evaporate almost completely and do not remain 

 behind in the dried film. The only substance remaining which binds 

 the solid particles of the pigment together is the oil. 



Preparation of Surfaces for Painting. All surfaces should be 

 clean and as dry as possible before the application of an oil paint. 

 Much new wood is very difficult to paint. The resins in such woods 

 as yellow pine and spruce tend to destroy any paint that is laid over 

 them. When possible, it is well to allow a new house to stand un- 

 painted for at least six months or even a year after the woodwork has 

 been completed. By this exposure to the weather the resins are 

 brought to the surface and are either washed away or hardened, and 

 the resulting wood surface is in much better condition for painting 

 than is a new structure. Painters adopt several methods of treating 

 new wood ; probably the one most universally used is to coat all knots 

 and other places where resin appears with shellac varnish, a solution 

 of gum shellac in alcohol. Another plan is to mix with the priming 

 coat of paint a small amount of benzol (coal-tar naphtha), which is 

 claimed by some excellent authorities on painting to dissolve the 

 surface layer of resins and allow the paint pigment to penetrate into 

 the fibers of the wood, preventing the final forcing of the resins to 

 the surface. After applying the priming coat, all nail holes and 

 cracks should be well filled with putty pressed in hard. Filling in 

 with putty should not be attempted before the priming coat is ap- 

 plied, as it is not likely to stick as well. In painting iron surfaces all 

 rust and grease should be carefully removed, scraping the surface 

 down to bright metal with wire brushes or sandpaper and finally dust- 

 ing off all adhering particles. Painting should be done in warm, 

 dry weather. It is much better to select the summer time fop 

 painting than the winter. 



