Actually the process of varnishing or painting the woodwork and metalwork on the house is the spreading of a thin protective coat, one thousandth part of an inch thick or less, over the surface, in order to protect it from the wear and tear of use and weather and decay. And a marvel it is that any material could be found which spread in so thin a film could withstand the chemical action of the sun's rays, the expansion and contraction of the surface over which it is laid, the abrasive action of blown sand, hail, and rain, the natural wear of walking feet and rubbing clothes and bumping furniture, and a dozen other accidents which conspire to mar the surface of woodwork in the home.
Is it a wonder that for this protective coat of varnish all experts demand that the best materials be used ? But out of ignorance it is not always so, for the lower cost of varnish and paint is more evident than the quality of the substance of which they are made.
The varnishes which are most used in good houses are made of resins, melted in a kettle and mixed with linseed-oil, and thinned with turpentine as they cool. They have the peculiar property, when spread with a brush over a surface, of hardening by a chemical change brought about by absorbing oxygen from the air, and making a strong, transparent, protective coat over the substance upon which they have been applied. The kind of resins* have much to do with the quality of the varnish, since the linseed-oil and turpentine are apt to be about the same grade in all varnishes. Dark or light varnishes can be made; hard or soft and elastic surfaces can be produced; varnishes capable of resisting the wettest kind of weather and those which turn white under the least dampness are manufactured for various purposes, and practically in all cases those varnishes which are the best are the highest in cost.
The cheap varnishes which are the most abundant upon the market, and which are used for cheap furniture and houses, are made of rosin and not resin, or are resin varnishes adulterated with rosin. Most houses erected by speculative builders are finished with cheap rosin varnishes, but no architect should be guilty of specifying them, for he should know better than to attempt to save money by purchasing the poorer grades of varnishes, since the real cost of varnished work is in the labor rather than in the cost of the materials used. These cheap rosin varnishes cannot stand up under the sponge test, which is merely the application of a wet sponge to the surface overnight. The next morning the rosin varnish will be found to be white and dissolved down to the wood, and will never recover its appearance. Better grades of varnish may turn white under this sponge test, but upon drying return to their original color, but the finest grades of varnish will not be affected at all. The difference between these varnishes can also be observed by rubbing the thumb over the surface of such a fine varnish as is on a piano and noticing that no effect other than a higher polish is produced, while if the same rubbing is done on a cheap varnish, it will be crumbled off from the wood. Every one has seen the ugly surface cracks which develop with age in old doors or upon old church pews in musty churches of the dark ages of American architecture. In nearly all cases these cracks are due to cheap rosin varnishes.
* Varnish resins or gums are imported from countries that the average man knows little about. The island of Zanzibar furnishes one of the costliest and finest of gums. It is called Zanzibar copal and is the gum of a fossil tree. New Zealand furnishes the most widely used gum, kauri. It is dug out of the ground by the natives. The west coast of Africa furnishes the gum known as Sierra Leone copal, which is used much in automobile work.
Before varnishing or painting any interior woodwork, it is important to observe all the preliminary precautions, or else failure may result, even though the work is conscientiously performed in the latter stages. One of these early precautions is to paint the back of all trim for doors and windows with some good linseed-oil paint, and apply a first coat of filler to the outside surface, and all this as soon as it arrives on the job. This is to prevent the wood from absorbing the dampness which is prevalent in all new buildings, and as most trim has been kiln-dried beyond ordinary requirements for construction work, it is very thirsty for water, and will soak it up quickly from the atmosphere. This trim should not be permitted to stand in the building overnight without the priming coat. As the first coat of filler is linseed-oil, there is not much excuse for not doing this, for it can be applied very rapidly. Of course where the wood is to be stained with an oil stain, the application of the linseed-oil before the stain is applied will prevent the proper penetration of the stain into the wood, and, as the architect generally insists upon seeing samples of the staining work before it is applied, the above precautions of protecting the wood as soon as it comes are often thrown to the winds.
And in connection with this matter of stains, a word may not be amiss. Most manufacturers make among their many stains certain brilliant-red mahogany colors, bright Irish-green colors, and horrible yellows. These are made to meet certain gaudy tastes shown by the public, but of their use by architects no word could condemn them enough. And on a par with these stains is the varnishing with no stain at all of yellow-pine trim, an architectural atrocity which is committed on every hand in small houses. The quiet browns, grays, grayish greens, and the like are the only safe ranges of color for staining interior trim, for, after all, the casing of doors and windows must blend in with the walls and serve as a background for the furniture and not screech at it. And directly in line with this statement should be emphasized the rule that highly polished surfaces in varnishes for trim are as much out of place as brilliant colors. Many architects prefer wax in place of the polish of varnish, and with good reason. The manufacturers of varnishes make certain grades which dry with a dull finish, and also show samples of beautiful dull finishes which can be secured by the laborious method of rubbing the final coat of varnish with powdered pumice-stone, water, and felt.