Electroforms for the book printing press in the nineteenth century: a case study on production technology and long-term corrosion

Abstract

This study examines the production process and long-term corrosion behaviour of 19th-century electroforms used for letterpress printing, based on a historical tutorial from the collection of the Technisches Museum Wien, Vienna, Austria. The composition and degradation mechanisms of the printing forms has been analysed by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX) and gas chromatography-mass spectrometry (GC–MS). The results indicate that the original woodcut carries remnants of gypsum from the mechanical detachment process. The wax matrix was composed of beeswax with traces of Venice turpentine. The electroforms consist of a copper layer with minor lead impurities, backed by a Pb–Sn alloy. Corrosion analysis revealed preferential oxidation of the less noble metal Pb, leading to interfacial degradation between the Cu electroform and the type metal. There, delamination of the Pb oxide layer on the type-metal phase was also observed, as this oxide shows a higher volume increase than the mixed Cu-Pb oxide phase. These findings provide insights into historical printing technologies and highlight key factors influencing the conservation of electrotypes. Proper storage conditions with controlled humidity and minimal exposure to acidic vapours are crucial for their long-term preservation.