The Structural Conservation of Panel Paintings

The flexible auxiliary support and tray, in addition to retaining the panel,

damp^8 its movement by applying a measured restraint while allowing con-

vex and concave (or reduced-curvature) movement. The flexible battens

accommodate an increase in curvature while encouraging a return to the

neutral position against the shaped profileof the panel tray. The back

spring accommodates concave or reduced curvature and also encourages

a return to the neutral position toward the panel tray profile.

The assembly is composed of several parts: the flexible batten, the

back spring, the central bearing, and the bases (Figs. 6–9).

Flexible batten

Flexible battens, if correctly rated for flexibility to the panel, are able to

be deflected by the panel. This allows for an increase in curvature when

the RH drops (Fig. 10). The interdependency of the flexible batten and the

back spring should be noted. The flexibility ofthe batten is increased

toward the tip by one of the following methods:

Tapering of thickness

This method involves the reduction in the thickness of the batten by thin-

ning toward the tip from the center. This reduces the stiffness toward the

tip, thus alleviating the problem of all the loads being referred inward

toward the central area of the panel and, consequently, increasing the

moment^9 toward the central axis.

Tapering ofwidth

This method (as outlined in Marchant, “Development of a Flexible

Attached Auxiliary Support,” herein) is also suitable and may be preferred

because graduating the flexibility is more accurate and more easily

achieved. (The number and spacing of the flexible battens are covered in

Principle of the Auxiliary

Spring System

376 Bobak

Tray

Flexible

batten

Panel

Back

spring

Central

bearing

Base

Backboard

Flexible

support

spring

assembly

Tray

a b

Panel

Flexible

support

spring

assembly

Backboard

Figure 6a, b
Complete system (a) consisting of a tray,
panel, flexible support spring assembly, and
backboard; the same components are shown
disassembled (b).