Assembled and detail drawings are first made in pencil on a quality of heavy white or straw-colored paper which will stand considerable erasing. A sheet of tracing cloth is placed over this work, when completed, and the work copied, or traced, in ink. The tracing is then used for making blue prints or black prints and is kept on file in the drawing room. Many drawing rooms are provided with a fire and water-proof vault for the safe keeping of valuable tracings.