Could facing techniques be compatible with optimal bone preservation surface?

Abstract

Bone usually requires conservation treatment during excavation. Some of the most common interventions are facing techniques to reinforce the specimens during their extraction in the field. This consists of the attachment of a fine tissue with a reversible adhesive, usually an acrylic resin, directly over the surface of the specimen. This interacts directly with the surface, which might link to the loss of bone surface information. This experiment focuses on the possible modifications that facing techniques could cause on bone surfaces with cut marks. Experimental bones with cut marks were artificially aged to reproduce the decayed process of archaeological bones. Different groups of bone samples were faced and exposed in two contexts for one year: indoors and outdoors. Bone surface and cut marks were documented before and after the facing and storing phases with 3D Digital Microscopy. In the indoor bones, cut marks show abundant traces of resin. Conversely, bones preserved in an outdoor environment displayed a high modification of their colour and an extremely poor state of preservation. Some cut marks disappeared completely or partially. Visual comparison allowed us to evaluate possible loss of archaeological information produced by the treatments. Facing techniques should be carefully monitored to guarantee its short-term contact with the bone surface and avoid these modifications.