Spark Printing

Spark printing is an obsolete form of computer printing which uses a special paper coated with a layer of aluminium over a black backing, which is printed on by using a pulsing current onto the paper via two styli that move across on a moving belt at high speed.

Spark printers were originally introduced in the late 1960s.

Spark printing was a simple and inexpensive technology. The print quality was relatively poor, but at a time when conventional printers cost hundreds of pounds, spark printers' sub-£100 price was a major selling point. The other major downside is that they can only print onto special metallised paper; such paper is no longer readily available. Spark printers were used by Sperry Univac as hard copy operators history for mainframe computer installations in the mid 1980s. The slow speed and poor quality was not an issue. The print mechanism was like a small set of 9 fingers that dragged across the aluminium paper surface. When a 'dot' was required as part of a character the current would be applied to the specific finger at a specific point and the aluminium was vaporised, the black under layer showed through. Sometimes the mechanism would not lift the fingers for the return journey, or the paper would not be lying flat; the result was the fingers would be torn out of line and the printer was effectively broken until a new head was fitted.