Production of Hand-painted Magic Lantern Glass Slides: A Literature Review

Hand-painted magic lantern glass slides frequently present significant conservation problems, mainly due to the painting's deterioration and detachment from the glass support surface. However, the study of these objects is a very recent field. This work reviews the materials and techniques applied to hand-painted slides until the nineteenth century in Europe and North America to follow their evolution throughout time and place, aiming to further our understanding of the slides' historical, cultural, and artistic impact. This review identifies 22 historical sources from five countries, written between the eighteenth and nineteenth centuries, containing information on the production of hand-painted slides, from the glass support to the painting materials and techniques. The production processes changed from the mid-seventeenth to the eighteenth century with the apparent transition from fired paints (enamels) to cold paints (watercolours, oil colours, and varnish colours). Different stages of eighteenth- and nineteenth-century production processes are explored. Concerning the glass support, crown and plate or ground-polished glass (later patent plate) were commonly advised. Although the paintings' palette was mainly restricted to transparent colours, around 70 colourants and 25 binding medium components are listed. Their chronological distribution unveiled a possible correlation between their evolution and the advent of the Industrial Revolution. The knowledge of the original materials and techniques will not only contribute to understanding the differences between locations, periods, and slides' producers, helping in future attributions, but will also support further investigations on the key factors and mechanisms that lead to the degradation of historical hand-painted slides, enabling the improvement of current conservation practices.