Short description of the natural and scientific foundations
of the spectroscopic dating of
wood
 

The essentials in brief

Infrared spectroscopy is not a new method or a new discovery. New is only its application for the ascertainment of age and authenticity in art. It has been used for decades the world over by all chemical and pharmaceutical companies with thousands of instruments and with the same programme and equipment as the ones used by the laboratory of the Museo d’Arte e Scienza. Its extreme reliability, accuracy and facility of use have made IR Spectroscopy the number one scientific method in all the fields where it can be applied.

Spectroscopic dating is based on two well-known factors:

·         All the natural materials on earth, including those used for creating art objects, are compounds of specific molecules.

·         Some particular molecules undergo changes with the passage of time.

The IR spectrum of wood shows its molecules or groups of molecules as peaks and valleys (Figures 1, 2). Signs of age caused by evaporation, oxidation and new combinations cause the lowering of some absorption peaks and, to a lesser extent, a shift in the same (Figure 3).
This dating method therefore offers two possibilities for the evaluation of the spectrum, each one already giving good results singly.

1 – The graphic evaluation of the curve (Spectrography)
Right from the start of this research, the spectrographic measurement of the angle (α) formed between peaks of different heights permitted a dating accuracy of +/- 20% and these findings were communicated at the time, around 1995, to a number of European museums and institutes.

Figure 2

Figure 1

2 – The evaluation of frequency shifts      (Spectroscopy)

The discovery of shifts in absorption frequencies in spectroscopic analysis has boosted accuracy over the years to an unexpected extent and was inexplicably high in the first few years.

At present we are attempting to trace this accuracy, as well as independence from climatic conditions, to biological programmes inside the cellular nucleus of the tree. The incredible precision of these types of biological programmes in general are well-known and understandable for the growth of wood. An answer to the question why the ageing of wood must also be programmed can be supplied only by the evolution of cellular research.

Tree cells, unlike animal cells, are highly protected by a wall of cellulose, a hydrocarbon. Cellulose is extremely resistant to water and wood cells as well as datable wooden material can still be found in excavated Roman ships.
 

Research in collaboration with a German
archaeological museum (1995).

               
Generation of reference tables to relate spectrum data to wood age:
 
The assignment of a spectrum to a specific wood species and to a specific age required the measurement of a great quantity of wooden objects of certain dating. This research, which called for many years of work on the part of qualified personnel was made possible only by the close and benevolent cooperation of international museums which began around 1993. The collaboration of some art museums terminated around 1995, since their curators feared there could be negative consequences for their collections. The Gottfried Matthaes Foundation, proprietor of the Museum, is, like the P. Getty Foundation, a non-profit organization at the service of art. Our cooperation with technical museums has continued.

The application of spectroscopic analysis for the dating of organic materials is patented
(It. Patent Nr. 01266808 - G. Matthaes, 1993)