An old notice board at ancient Herculaneum studied using Near Infrared Reflectography.

An old notice board, a rectangular plastered area on a brick wall, placed on the east side of the castellum aquae, a pillar, situated near the crossing between IV cardo and decumanus maximus at ancient Herculaneum (Italy) has been analysed using Near Infrared Reflectography (NIRR). The notice board was used to display inscriptions (Tituli Picti) painted on it and was used at least twice hiding older inscription under a whitewashing layer (dealbatio). In 1930s Amedeo Maiuri excavate the castellum aquae and Matteo Della Corte transcribed the visible inscription and removed it by mechanical abrasion to read the underlying (and older) one that resulted only partially readable. The notice board presents several open questions of interest for archaeologists: no graphical or photographic documentation of the removed inscription is available so that its layout is unknown; currently visible inscription (the older one) has been damaged by mechanical abrasion and environmental action so that it is impossible to understand the subject of the edict; the presence of two superimposed inscriptions suggests the possible presence of other ones. NIRR is a non-destructive imaging technique based on the different optical behaviour of pictorial layers under visible (VIS) and near infrared (NIR) radiation and is mainly used in painting analysis to allow reading of under-drawings or ‘‘pentimenti’’. The use of this technique has been able to give at least partial answers to the open questions concerning the notice board: NIR images increase the readability of the currently visible inscription, evidence traces of the removed (ablated) inscription and allow reading a new (underlying) inscription written in cursive using some fortuitous material.