Peter S. Champe
As one solution to the problem of structural repairs which require dowels or rigid reinforcing elements of irregular size or shape, I have had success in two treatments using heat-fused pellets of adhesive resin or “resin-sticks”. In the reattachment of the highly deteriorated wooden arm of a Northwest Coast Indian beaver headdress, a difficulty arose in the fact that the break occurred at the elbow which described a roughly 90 degree angle. The angle of the join forced me to look for a material which could be easily shaped yet was strong and rigid enough to act as a dowel. A B-72 resin stick, made to the desired thickness and shaped to the correct angle was used successfully.
The second treatment involved the reattachment of the wing of a small 12th century gilt copper Limoges angel. As the splint used here had to be very thin, the characteristics of the resin were carefully considered. The PVA resins AYAF and AYAC were found to be too flexible while B-72 and B-48n were found to be too brittle. A good mixture of rigidity and strength was found in a 50/50 mixture of PVA-AYAT and B-72. Some issues to consider in this treatment are the possible effects of off-gassing of PVA’s on copper and the compatibility of different resins such as methacrylate and PVAs. There will be a short discussion of factors affecting the physical characteristics of resins including polymer chain length, functional groups and branching. Actual samples of various resin sticks will be available for fellow conservators to examine.