1 INTRODUCTION

THE PHRASE “RESTRAINT WITHOUT STRESS” refers to an ideal state of structural security in a fabric-supported painting, in which the painting is in plane, with no sagging, deformation, or stress build-up. Unfortunately this ideal is seldom attained, since immediately upon completion, or perhaps even before, fabric-supported paintings are subject to factors both internal and external which lead to cracking, cupping, and cleavage. These symptoms of mechanical failure are so common in aged fabric-supported paintings that custodians of paintings take them for granted. However, a rational approach to the construction, care, and treatment of paintings could prevent this type of structural deterioration with its attendant irreversible blemishes and loss of both aesthetic and financial value. When simple observation reveals the great number of paintings only one to fifty years old already displaying extensive cracking and cupping, the utility of being able to predict which paintings are likely to fail, when, and under what environmental conditions, and what are their efficacious preventative treatments, becomes apparent.

One thesis of this paper is that we in conservation, in spite of recent advances in the field, still do not know enough about the forces acting on (externally) and in (internally) fabric-supported paintings in order to choose appropriate treatments either to remedy defects without unforeseen and undesired side effects or, even more important, to prevent damage from occurring. The other thesis of this paper is that to assess where we are, it is important to see where we have been. A survey of past and past-proposed research, seen from the perspective of the present, will help us to see where present ideas have come from, what the fundamental issues are, and what remains to be learned.