TWELFTH ANNUAL YEAR BOOK— PART X 507 



to stand unpalnted for at least sis months or even a year after the wood- 

 work 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. An unpainted house, however, is an unsightly object, and 

 it is often desired to paint a new house at once. 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 naptha), 

 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 sur- 

 face. 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 applied, as it is not likely 

 to stick as well. 



In painting iron surfaces all rust and grease should be carefully re- 

 moved, scraping the surface down to brie'ht metal with wire brushes or 

 sandpaper and finally dusting off all adhering particles. 



Painting should be done in warm, dry weather. It is much better to 

 select the summer time for painting than the winter. Not only does the 

 paint not flow so well in cold weather, but the surfaces of the painted 

 objects are more likely to be moist, and a little moisture underneath 

 the paint film, either on wood or iron, is very apt to cause serious trouble. 



PAIXTIXG EXTERIOR WOODWORK. 



All wood is more or less porous, and the natural result of applying a 

 substance like paint to such a material is that the liquid portion sinks 

 into the wood ard leaves a large portion of the solid material on the 

 surface. Also different parts of the wood will differ in porosity, and 

 there will tend to be different amounts of paint left on different portions 

 of the surface. In order to do a good job of painting it is practically 

 always necessary to apply several coats to new wood. The first or prim- 

 ing coat is made thinner than the others, the amount of thinning depend- 

 ing upon the porosity of the Vv'ood. For ordinary pine, a paint of proper 

 spreading consistency, when mixed with an equal volume of raw linseed 

 oil, generally furnishes a good material for priming. With very porous 

 wood, such as redwood, more oil may be added. The priming coat should 

 be applied with as much care as any other and should be thoroughly 

 brushed into the wood, the brushing being carefully done so that the 

 paint is evenly distributed, with no tendency to run. It is the custom 

 of many painters to add a great deal of drier and of turpentine to the 

 priming coat, and to apply the other coats almost immediately after 

 finishing the priming. This is not good practice. The paint for priming 

 should consist of the pigment, linseed oil, and a minimum amount of 

 drier, with no turpentine or benzin; and after applying it at least a week 

 and preferably longer should elapse before putting on the second coat. 



