In general a window may be said to consist of three parts - the frame, the sash and the inside finish - and each part is usually described separately in the specifications. The material for all those portions of the frame which are exposed to the weather should be clear Eastern or Northern white pine, sugar pine, cypress or red wood, white pine being generally preferred.
The piece called the "pulley stile" is frequently made of hard pine, and sometimes of hard wood, because such woods wear better under the friction of the sash in sliding up and down. Whether of hard or soft wood, the pulley stile should never be painted, but simply oiled or stained.
The concealed portions of the frame are usually made of spruce, the cheaper grades of white pine, or of the most common wood of the locality. All of the material should be well seasoned, and frames that are to be placed in masonry walls should be painted or oiled all over before they are set to keep out the dampness.
Occasionally the window frames of public buildings are made of cast iron, and quite frequently in office and mercantile buildings the outside of the wood frame is covered with cast bronze or bronze plated iron.