The Black Hours: Material and Conservation Study, Part 1

The Book of Hours of Galeazzo Maria Sforza, V. Duke of Milan (Vienna, Austrian National Library, Codex 1856), the so-called Black Hours, is a Flemish illuminated manuscript with silver and gold ink on black coloured parchment from the third quarter of the fifteenth century. The severe deterioration of the parchment by the black colourant resulted in brittleness and numerous losses. This paper describes the history of the manuscript and previous interventions. The condition of the various materials was assessed and put in context with the other six black manuscripts that have been preserved worldwide. The fibre morphology, the hydrothermal stability and the investigation of the fibre structure in the Scanning electron microscope confirmed the degradation of the parchment fibres. The black colourant was identified as iron gall ink by X-ray fluorescence spectrometry (XRF) and Raman spectroscopy. The elemental composition of silver and gold was analysed with XRF. Based on these results, a model conservation treatment and a new preservation solution were developed.