@moira@mastodon.murkworks.net @connections@tacobelllabs.net The paper has metallic fibres in it to become conductive, while the back is carbon black Applying current burned part of the front off to reveal the carbon underneath. Was used for early low cost printers; such as the Western Union Deskfax, Sinclair ZX printer, many of the early scientistic calculators. Was also used by things like seismographs.