Spark printing

Printing on this paper uses pulses of electric current to burn away spots of the conductive layer.

Typically, one or more electrodes are swept across the page perpendicular to the direction of paper motion to form a raster of potential burnt spots.

Western Union developed the paper for this printing technology in the late 1940s, under the trademark "Teledeltos".

[1] The Western Union "Deskfax" fax machine, announced in 1948, was one of the first printers to use this technology.

The Sharp Corporation ELSIMATE EL-8151 portable calculator had a built in spark printer which used silver-colored paper.