Thermal paper is a copy paper which uses heat to produce its image. The National Archives is concerned about the proliferation of thermal papers in archival records because the images are very unstable and tend to fade quite rapidly.

Where are thermal papers used?

Thermal papers are commonly used in facsimile machines and as the printout paper for digitally scanned images, including electronic whiteboard printouts. They are also used for printing tonal images such as photographs and for computer assisted design drawings.

The properties of thermal paper

Thermal papers have a chemical coating on their face which darkens when heated. In the copying process the image is produced through the action of a heated stylus passing over the paper.

Thermal papers themselves are usually quite thin and have a shiny surface on the image side. They can be easily identified, as a black mark appears when the coated side is scored with a fingernail.

Warning to recipients of fax documents

The recipients of facsimile documents need to be alerted to the possible loss of information from thermal fax copies. Adding a warning (similar to the example below) to the transmission sheets used to head facsimile messages can help.