Matrix, printing matrix

These matrices were used by typesetting machine operators at The Guardian newspaper on Farringdon Road. The typesetting machines produced lines of text called 'slugs'. These were cast in molten lead alloy from lines of matrices (letter dies) and space bands which were sequenced and justified. The molten metal was heated electrically inside the machine.

Lines were typed using the machine's keyboard. When operators pressed the keys the matrices and space bands would be released from the magazine above in the desired sequence. After the slug had been cast the matrices and space bands would be rotated back to the magazine to start the process again. The lugs of the matrices and space bands would often require cleaning and lubrication. This would be done by rubbing them on a soft pine board and graphite.

The Guardian stopped printing using these 'hot metal' processes in 1987. The following year the newspaper donated a Harris Intertype Monarch typesetting machine and various hand tools to the Museum of London.