By Emma Laws, Cathedral Librarian
Prior to the 16th century, mapmakers printed maps using a ‘relief’ method of printing: wood-engraving. The engraver drew the image of the map onto a block of wood and then cut away the wood on either side of the lines to be printed leaving the design as a raised surface – in ‘relief’. The printer applied ink to the raised lines and pressed a sheet of paper to the wooden block, transferring the ink from the block to the paper. There were drawbacks to wood-engraving: it was difficult to achieve fine detail, and the woodblocks were susceptible to wear and tear. Also, trees are only so big and large maps could only be printed using several woodblocks pieced together.
Printing with copper plates became the standard method of printing maps from the late 16th century. Copperplate printing is an ‘intaglio’ method of printing: the engraver cut the image of the map into a sheet of copper using a sharp metal tool so the lines to be printed were recessed. The printer applied ink to the copper plate, pushing it down into the recessed lines, and then wiped away any excess ink lying on the surface of the copper plate. The printer then placed a sheet of paper on top of the inked copper plate and put the plate and paper through a press. The press exerted so much pressure that the ink was drawn up from the recessed lines in the copperplate onto the paper. The engraver could achieve very fine detail as well as textures and tones – shallow incised lines held less ink and printed lighter than deeply incised lines that could hold more ink. Large copperplates, although heavy, were ideal for printing large maps.
This is the engraved copperplate of the Ecclesiastical Map of the Diocese of Exeter, commissioned by the Rev. H. Bramley in 1878 and printed in London by Stanford’s Geographical Establishment, the foremost mapmaker in the country. The first thing you will notice is that the design engraved on the copper plate is in reverse – a mirror image of the final printed copy. And the map is printed in black and white – you had to pay extra for a hand-coloured map.