The Structural Conservation of Panel Paintings

were 1 cm thick. The sawing was done in a transverse direction on end-

grain wood in order to obtain elements that were as rigid and as easy to

work with as possible.

The adhesive is a mixture of seven parts beeswax and two parts

damar resin. This adhesive is one that has been used for fifty years by IRPA

for certain relinings of painted canvases and for consolidations of paint

layers as well. To make the adhesive, raw beeswax is obtained from a bee-

keeper. It is then washed in boiling water and filtered. This weak adhesive,

solid at room temperature and liquid at 60 °C, is stable and flexible, and

it can be easily dissolved or reactivated. It is also a good barrier against

humidity. It impregnates only the surface of the wood. The reverse of a

panel is traditionally sized with rabbit-skin glue at the time of manufac-

ture. This method of insulation, which prevents penetration of the wax, is

an option to consider before backing.

Before a panel painting is backed, the adhesion of the paint layer is exam-

ined. A facing is applied to the painted surface, the joints and splits of the

support are glued, and the lacunae in the wood are filled.

The painting and the balsa blocks are then brought to the same

RH level. With a brush and spatula, a layer of warm wax-resin is applied

over the entire reverse of the panel, in order to level the irregularities in

the wood surface. The wax-resin mixture shrinks as it cools. To control

the extent of shrinkage, it is applied in thin, successive coats. The balsa

blocks are immersed for a few seconds in the melted adhesive, positioned

on the cooled layer of wax-resin on the panel’s reverse, and held in place

until the wax cools.

The joints between the blocks are aligned diagonally with regard

to the grain of the boards that form the panels. Two levels of blocks are

glued in this way, the second level being staggered so that the joints are

not superimposed. Experience has shown that the joints are the weak

point in the handling of panels, and therefore, that a rigid support is desir-

able. The most rigid support is achieved with balsa blocks sawn in a trans-

verse direction, then placed in two staggered layers, diagonally with regard

to the panel’s grain.

Asheet of very thin, long-fiber paper (12 g m^22 ), such as bamboo-

fiber paper, is next glued with wax-resin to the backing. After gluing, this

paper is transparent. It allows for the control of the possible opening of

the joints, and it holds the blocks in place in case of significant ungluing.

The treated panel must be replaced in its frame, which fulfills a

dual function: it distributes strains during handling, and it supports the

painting when it is hung.

A balsa backing was carried out in the conservation-restoration workshop

at La Cambre school, Brussels, where the author teaches. Paul Duquenois,

afifth-year student of painting restoration, was in charge of this treatment.

The painting, which represents the Adoration of the Magi, is a

seventeenth-century oil-on-wood panel attributed to a member of the very

productive Francken family of Antwerp. The support consists of three thin

(8 mm) oak boards, sawn on the false quarter and held together with pins.

The panel measures 71.4 3 104 cm. The seal of the guild of Antwerp, a

castle and hands, is stamped on the reverse.

Straightening of a

Distorted Panel

Method

366 Glatigny