This type of roof is rather expensive for the small house, even with the reduced cost of copper, and for this reason a lighter grade has been made, and offered for use in the form of pressed-metal shingles of very flat design. These copper shingles have been treated so that other colors than the copper shades can be secured.
The zinc manufacturers have also placed on the market zinc shingles of special interlocking flat design for use on small houses.
It has always been a debated question as to whether pressed-metal shingles were architecturally permissible. Certainly there are some forms which imitate the clay tile shingle that are decidedly inartistic, but the more natural flat patterns are less subject to this criticism.
XV
PAINTING AND VARNISHING THE HOUSE
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[A] 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.
[A] 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.