Roberto Furnari

Violin Making & Dendrochronology

Dendrochronology

Basic principle

Dendrochronology is a wood dating method based on the comparison of tree ring patterns.

Tree rings represent the annual growth of a tree. Their width varies from year to year due to changing weather conditions, the main factors being variations in temperature and precipitation. Over the course of many years, the succession of wide and narrow rings forms a characteristic growth pattern that can be used to precisely anchor in time wood of unknown age.


Cross-section of a tree with distinctly visible year rings.


Dendrochronology applied to musical instruments

The main purpose of a dendrochronological analysis is to establish the earliest possible date of manufacture of an instrument. This allows for an objective verification of an attribution based solely on stylistic features.

As a matter of principle, a dendrochronological date by itself can only support an attribution to a particular maker and never serve as a proof of authorship.

On the other hand, if the date of death of the assumed maker predates the dendrochronological date, an authorship can be categorically excluded. As a consequence, dendrochronology is a valuable tool in terms of uncovering erroneous attributions and, more importantly, plain forgeries.


Detail of a violin belly. Resonance boards of violins, violas, cellos and double basses are typically made of Norwegian spruce (picea abies), which lends itself particularly well for a dendrochronological analysis.


Method

As a first step of the analysis, the width of each individual tree ring is measured with a 1/100 mm accuracy using high resolution images of the top plate under investigation. No wood removal is required - the procedure is absolutely non-invasive.

The resulting measurement series is then checked for matching growth patterns against a dated reference sequence using both graphical and statistical methods.

If the synchronisation is successful, the graphs of both series will "snap into place" – like a key into its lock, so to speak - enabling the attribution of a date to the exact year.

In practice an undated sample is never checked against a single reference sequence, but against a database of measurements including thousands of dated tree ring series. Only results that are supported by multiple references are accepted as valid.

In some cases the comparison with available reference data does not yield any match and, as a result, no date can be established. By using a dedicated database for resonance wood, the current success rate is about 80%.


Graphical comparison of tree ring sequences. Visual evaluation of growth patterns is an essential part of a dendrochronological investigation.


Reports

After a successful dendrochronological analysis of your instrument, if requested, I will issue a written report. This is available in English or German and will include the following information:

  • the date of the youngest measured year ring
  • an indication about the geographical origin of the wood
  • significant matches with other instruments, if applicable
  • an interpretation of the result

If no written report is required, I offer a verbal communication of the results at a reduced fee.


Dendrochronological analysis reports constitute an invaluable addition to a thorough appraisal of stringed instruments.