In a step that was indispensable for restoration work, UV fluorescence was used by Prof Sebastian Dobruskin and Dr Nadim Scherrer of the Graduate School of the Arts in Bern (HKB|HEAB) to distinguish details of the spheres’ multi-layered surfaces. Various layers of varnish were detected which had been applied after the globes’ production. The celestial globe seems to have more surface varnish than the terrestrial one, which perhaps explains its better state of conservation.

Looking for watermarks

Besides UV fluorescence, infrared reflectography (IR) was used to try to detect any watermarks and thereby identify the paper component of the surfaces. Unfortunately, the thick layers of varnish prevented this altogether. IR nevertheless demonstrated that the globes’ surfaces had already been restored in the past and that the job had been well done.