The Structural Conservation of Panel Paintings

rings and other dendrochronological work with diffuse-porous species

more difficult than is work with ring-porous species such as oak.

The biological regularity of the ring series in trees of temperate

zones makes it possible to date wood by comparing the sequences of

undated wood with those of wood of known age. To establish comprehen-

sive continuous growth-ring curves for periods longer than a tree’s lifetime,

it is necessary to use an overlapping system of individual curves (Fig. 2).

An overlapping system is necessary for the establishment of these master

chronologies, because trees in Europe do not normally live more than two

or three centuries. Such standard curves exist, among others, for south

and west Germany, several regions of north Germany, several areas in the

Netherlands (partial), and the Baltic area, from which the wood for most

Flemish and Dutch paintings was obtained (Fig. 3) (Eckstein et al. 1986).

To determine the ring widths in wood, a magnifying glass with an inte-

grated scale may be used (Fig. 4a). This method is used if measurements

have to be taken without laboratory equipment at the site. It is more con-

venient and faster to take measurements in the laboratory using a station-

ary binocular and a traveling stage on which the sample is mounted. These

devices can be connected to a computer to record the data for immediate

use in subsequent steps of the analysis (Fig. 4b).

Cross dating in its simplest form is the comparison of two tree

ring sequences to determine if and to what degree they match, as well as

to determine their placement in time to each other (Fig. 5). If one of the

curves is attributed to a definite stretch of time, the positioning ofthe

Measurement and

Cross Dating

D A  P P 41

Figure 2
Overlapping system for the establishment of
master chronologies.