Sheena Porter started her career as a children’s librarian, before transitioning to editor at Oxford University Press, focusing on children’s books. In this role, she gained valuable insight into the processes of book production and illustration, which led to her becoming a children’s author. Her first novel, The Bronze Chrysanthemum, was published by OUP in 1961 and her last, The Hospital, in 1973.

Amongst the artefacts in the OUP archive is the book cover for The Hospital, illustrated by Robin Jacques, alongside three printing blocks for its creation. These are etched copper printing plates on wooden backing blocks, the customary way to make front cover images for children’s books in the 1960s and 70s. Each of the blocks is in a different coloured ink (blue, red, and yellow, or more accurately cyan, magenta, and yellow), and the copper plate images are all etched slightly differently so that the inks could be built up on top of each other to make the full colour image.

The process is known as CMYK, which stands for Cyan, Magenta, Yellow, and Key (Black). Layering different amounts of these four coloured inks can create a wide spectrum of colours.