448

A

 of paintings treated at the Hamilton

Kerr Institute (HKI) in Cambridge, England, have been on wooden

supports. This article uses examples to show the underlying causes

and mechanisms that determine treatment decisions in practice.

Scales ofdamage and treatment constraints

Large panels have sufficient weight and size in the cross-grain dimension^1

so that a number of considerations arise that are generally less significant

in smaller panels. Greater damages are found—breaks of greater number

and length and larger areas of biological deterioration—with correspond-

ing treatment implications. Liters of (usually toxic) consolidant may be

needed for a large volume of insect-damaged wood, requiring large-scale

application methods and large-capacity fume extraction. Thus, treatment

methods are scaled accordingly and should be made as efficient as possible,

while, ofcourse, being subject to conservation demands.

Structural stabilization concerns for large panels must be balanced

with restrictions in time, cost, and methodology. The greater logistics gen-

erally make treatment more difficult, demand more time and appropriate

methods, and therefore increase total costs. Satisfactory results may

require a complex treatment and some ingenuity.

Environmental considerations and wood movement

Environmental conditions are constantly changing, however slightly, so that

panels of wood are constantlymoving in response to changing moisture

content (MC).^2 Depending on the panel structure, such wood movementmay

be relatively small or slow, and therefore not easily perceived. Generally,

larger panels change MC more slowly, although movement may still be rel-

atively fast, especially for thinner panels. Even when housed with the best

environmental controls, panel paintings are unlikely to reach a stable equi-

librium moisture content (EMC) with level moisture gradients and cessa-

tion ofmovement.

Relative humidity (RH) should be as stable as possible during

treatment. Total lateralmovement (across the wood grain and in the plane

ofthe panel)^3 and warpmovement (perpendicular to the panel plane)

vary directly with the panel’s dimension across the grain.^4 The location

General Considerations

Practical Aspects of the Structural Conservation

of Large Panel Paintings

Al Brewer