In the Black: Ink-like Photo-reproductions on Tracing Cloth

Photo-reproductive processes for copying architectural and engineering drawings first became common in the 1880s with the introduction of the blueprint. While processes on paper have become increasingly identifiable in recent years, those on cloth remain less familiar. Tracing cloth is a plain woven, heavily sized fabric used as a durable and translucent support for ink tracings. Because of its translucency, the tracing could be used as a master to produce additional prints in varying processes. For this reason, black ink images on tracing cloth often served as the primary record set in many architectural o f fices. The original drawings on paper were frequently discarded. Tracing cloth was also used as a support for photoreproductive processes. Two black line techniques are particularly significant because they were viewed as permanent and durable facsimiles of original drawings that could serve as primary record sets. The carbon-based technique known as gel lithography and the silverb a s e d technique know as the CB process are often mistaken for ink drawings. Both processes were introduced about 1920 and continued in use through the 1950s. They are often mistaken for ink tracings. Accurate identification of these images as photo-reproductions is important since misident i fication can lead to inappropriate storage and preservation decisions. This paper will review the nature of tracing cloth used for drawings and photo-reproductions and then examine the characteristics and preservation needs of these two processes. I N T R O D U C T I O N