Original Blueprints from 1914 Expansion of Station

Union Station | Metro Denver

Installation Information

The documents that you see here are original working drawings for the large central waiting room that was expanded and opened to the public for the first time on October 31, 1915. The drawings are called “linens”. The use of linens, also known as tracing cloth, began in the 1850’s, but did not become widespread until the 1870’s. Tracing cloth is strong, durable and translucent which made it ideal for use as working drawings. Using tracing cloth, final inked working drawings suitable for blueprinting were traced from the original linens. Because of their properties, linens became the support of choice on which many firms maintained their permanent record set of drawings. While early tracing cloth was made from linen, manufacturers soon changed to long fiber Egyptian cotton. The cloth was coated with a heavy layer of starch to which various resins, such as nitrocellulose would be added and then heavily calendared to compact the fabric and impart a smooth surface. A blue dye was often added to improve clarity for photo reproductions made from the cloth. Because of its expense, the use of tracing cloth began to decline in the 1930’s and was eventually replaced by polyester film (mylars).