Safeguarding the relative position of fragments
After a whole segment had been faced-up with a small self-adhesive disc with a pencilled number stuck to the face of each separate fragment or group of fragments, a thin polythene sheet was laid over the segment and the shape and position of each numbered group was traced with an indelible marker, and a note was made of each number. The polythene sheet was then turned over and laid on a sheet of 6mm thick perspex. This provided a support for the fragments as they were released from the plaster of paris backing of their ‘parent’ segment.
It had been anticipated that the release of the Roman material from the plaster backing, put on when the painting was lifted on site, would be prove to be difficult. However, it was found that the junction between the modern backing plaster and the Roman material was quite weak, and that gentle tapping on the side of the modern plaster support backing with a small wooden mallet released the Roman material quite easily and without any evidence of damage to the paint surfaces.
After each fragment had been removed from the site backing it was laid, face down, on the numbered polythene numbered sheet, ready for the the removal of the surlus mortar.