www.spectroscopyforart.com                                            Last updating:  01/04/2008

Fondazione Gottfried Matthaes
 

Spectroscopic Dating and Classification of wood
in the laboratory of the Museo d'Arte e Scienza

 

The current situation for the scientific determination of the age of wood

 The oldest – and still the most commonly used – method for determining the age of antiques is based on the deterioration or modification of the material over time.
Some examples:  bronze and iron patinas, the craquelures of paintings, the fading of colours, the deterioration of wood, etc.
The lack of suitable instruments prevented absolute dating.

Halfway through the last century, two scientific methods were devised which immediately proved to be of extreme interest for the study of the Earth and of humanity. It was established and acknowledged, however, that their applicability for the dating of single antiques was scant. There is a vast literature on the advantages and limitations of these methods, also to be found on the Internet.

The invention of computer-aided spectroscopy, about 50 years ago, simplified and enhanced the analysis of materials. The composition of the same, particularly in the case of organic materials, is represented by the peaks and valleys of a curve (absorption spectrum) eliminating the need for costly and complicated chemical analyses. Variations, such as those induced by ageing, for instance, can be seen in this curve in the form of clearly visible and measurable displacements of the curve’s peaks.

Around 1993 Gottfried Matthaes, physicist and director of the Milan Museum, broke the barrier of the datability of wood by chemical analysis. It was discovered that the displacement along the curve of the absorption peaks of certain molecules corresponded to the progressive increase in their age independently of temperature, humidity, and place of origin.


Description of the method
 


How to take wood samples
 


List of wood types which can be dated
 


Scientific Laboratory
 


Advantages and criticism made

 

 

 

Acknowledged value
of the museum’s scientific laboratory and its methods
for determining authenticity


 

Attitudes towards and use of scientific methods are influenced by local laws and customs.

Basis of judgment: the situation in Italy (where the museum is located)

The prime institution for the fight against forgery and imitations is the Guardia di Finanza or Financial Police. The most recent catalogue on the determination of authenticity in art, published by the same in June 2007, contains an exclusive six-page presentation of the scientific laboratory of the Museo d’Arte e Scienza in which its methods for dating paintings, furniture, and objects in ivory and other materials are illustrated in detail and their validity, in effect, endorsed.

Judicial proceedings. The probatory value of the spectroscopic dating method is crucial to the outcome of civil and penal judgments involving the determination of the actual age of art works.

The art market: the percentage of unauthentic art works currently on the market is very high. As a consequence a section of the trade rejects scientific methods out of economic necessity. Furthermore, when dating tests give negative results, dealers often tend to maintain that it is not the art work that is at fault but the scientific test result, or that the method is unknown!!

Art lovers and investors. Copies and fakes will continue to be offered as originals as long as buyers of art refuse to follow the same line of conduct adopted when acquiring other “products”, that is to say insisting on a dependable guarantee of the object’s authenticity as the condition for its purchase. It is senseless to content oneself with the personal opinions of experts alone in this age of technology and science. The art market will become trustworthy only when the art lover becomes a connoisseur and, as envisaged by the law, demands a valid certificate.
 

 

 

 


 

NOW OPERATIVE !

Branch of the Milan scientific laboratory for determining the authenticity
of valuable antique art objects
 

The announced laboratory in Germany to serve central Europe is
now operative for the taking of samples from wooden objects to be dated and for the issuing of certificates.

 

Please contact Dr. Martin Matthaes
+49 (0) 17676305108 – mm@museoartescienza.com

The house, which has belonged to the Matthaes Foundation (Museo d’Arte e Scienza) for 45 years, is situated on the shores of Lake Constance, near Lindau.

For the USA you can contact an authorized person for the taken of wood samples
 

Other requests may be sent, as always, directly to the Milan laboratory at the following address:


Museo d’Arte e Scienza
Via Q. Sella 4 – 20121 Milano
Tel. 0039 02 72022488
Fax 0039 02 72023156

e-mail: info@museoartescienza.com

 

 

For further info:  

www.Museoartescienza.com     www.Spectroscopyforart.com    
www.PaintingsAuthenticity.com   
www.AfricanArtAuthenticity.com and other sites

 

 

 

The value of expertise on art in the scientific age

The judgement of a renowned expert or a famous auction house has, at times, the magic power to push an article’s market value up by as much as a thousand fold. Thus a fine piece of furniture, a painting or an African mask may just as easily cost €1,000 or €1,000,000. This disconcerting difference in value estimates is becoming increasingly common in the international market. This would be conceivable if the appraisal were based on meaningful and verifiable data. Unfortunately this is not always the case.

€ 4.500  
Authentic

 

€ 5.000.000
Auction of June 18, 2006


Over the centuries, well-to-do families and museums the world over have accumulated an unimaginable quantity of precious art treasures of incalculable commercial and art historical value. It is widely held, however, that over half of these works are not authentic. In the absence of scientific methods, such conclusions were based mainly on opinions.
A critical application of the new and accurate methods for ascertaining authenticity to this immense cultural heritage without the consent of its curators is neither thinkable nor desirable.

On the other hand, with the Internet and other media invading the homes of collectors and investors worldwide, it is inevitable that false assertions regarding technical methods for determining authenticity are revealed for what they are. By discrediting scientific analysis, the art market certainly also harms itself. As a result, buyers and investors are increasingly inclined to make their purchases from large and relatively reliable auction houses. There is a tendency in all sectors and small dealers are forced to close down. But it is precisely the art sector which could escape this trend.

Today gallery owners and art dealers are, in fact, in a position to complement their expert opinions with accurate scientific certificates, thus providing a more dependable guarantee of safer and fairer purchases than the large auction houses. Attitudes, as well as guarantees, need to be changed and scientific analysis should be seen as a useful and advantageous instrument and no longer as an obstacle or a threat.


There already exists a valid method, the IR Spectroscopy, since decades the most widely used analytic method in the chemical industry and in scientific research laboratories.


 


 

 

 

The spectroscopic dating and wood classification department of the Museum laboratory

 

Spectroscopic analysis workstation


 

Checking sample suitability

Checking possible use of old wood

 

Instructions on sample taking and prices are given on page 12


 


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

The essentials in brief

Infra-red 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 the IR Spectroscopy in all fields where it can be applied, the number one scientific method.

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 allows therefore two possibilities for the evaluation of the spectrum, each one already offering 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

 

Figure1

 

 


 

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.

(Figure 3) - The diagram to the left is only one example of the many characteristics of a spectrum.



At present we are attempting to trace this accuracy, as well as the 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.


The cell of trees, contrary to the cells of animals, is highly protected by a wall of cellulose, a hydrocarbon. Cellulose is extremely resistant to water and wood cells as well as datable wooden material are still existent in excavated Roman ships.
 

  Figure 4

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)

 

 

NEW !

Good news for friends of antique objects of art:
Ivory is datable!

Ivory object, Africa

Buddha temple, China

The term “ivory” comprises today not only elephant tusks, but also the tusks and horns of other animals and some types of bones. What distinguishes all types of ivory are their hardness and durability, characteristics due to their chemical composition.
For the most part ivory is made up of inorganic substances, the age of which is not measurable. There is also a presence of organic substances which undergo change with the passage of time following biological laws.

Infrared spectroscopic analysis identifies the molecules present in ivory enabling the inorganic substances to be clearly distinguished from the organic ones. For organic substances it is possible to apply focused analytical methods to selected and measurable molecules.

The spectroscopic curve permits the unmistakable recognition of the various kinds of ivory and therefore the elaboration of specific calculations for the dating of each type
(Fig. 1 - 2).
 

Fig. 1

Fig. 2


Important! The molecules constituting ivory cells are not protected by walls like wood cells. Ivory samples for dating need to be appropriately stabilized immediately after they are taken.

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

Instructions on how to take ivory samples for dating

A)        The ivory object is sent to the laboratory of the Museum in Milan. This procedure allows to take the sample with the minimum and invisible damage.
B)
         The ivory sample is taken by the owner of the object. For the dating we need a minimal fragment of ivory (10 mm3 volume - mm 3x3x1) which can be taken from the edge or a corner of the object with a very sharp knife or a small coping saw.

The obtained fragment must be put into a piece of paper, to be folded carefully and mailed directly to the Museum laboratory. Price for one measurement: 95 Euros, $ 125.

 


 
Reliability and accuracy of the spectroscopic method

The need for a new method applicable also to single antiques

Fifteen years ago the spectroscopic dating method based on wood decay over time was introduced in Milan, Italy. The search for a new method was begun in 1980 because existing methods, the C14 method and Dendrochronology, owing to their well-known intrinsic limitations, could not provide certain results for the scientific dating of the approximately 1,000 wood antiques belonging to the present Art and Science Museum. This situation was common to almost everyone who has anything to do with antiques.
The C14 method and Dendrochronology continue, nonetheless, to be indispensable methods for the dating of very ancient objects and for the history of humanity.

Testing the validity of the new method
After 3 years of experimentation in effecting measurements and compiling tables for the calculation of age on the basis of spectroscopic frequencies, in 1994-1995 our laboratory approached some important international museums requesting their collaboration in testing the method and improving the tables for the dating of the wood of presumably antique objects. The proposal was favourably received. Six of these museums were invited to provide us with two types of wood samples: (A) Wood from objects of certain dating for the calibration of the tables. (B) Blind samples, without any indications of age, the spectroscopic dating of which permitted them to evaluate the validity and precision of the method. The results of these comparisons demonstrated the accuracy and reliability of spectroscopic dating.

The following tables show, for instance, the results of the collaboration of two prestigious museums
(the data can be viewed at both the cited museums as well as at the laboratory of the Milan museum):
  

I - Deutsches Museum, München
.
41 measurements on four dispatches of samples (August 1994, March 1995) with completion of the measurement of all the objects of the museum to be dated.
 

           OBJECT          

AGE PRESUMED BY DEUTSCHES MUSEUM

SPECTROSCOPIC DATING AND CLASSIFICATION OF THE WOOD

Aufrechter Flügel

1750/70

1750 +/- 20

Conifer

Orgelpositiv

after 1750

1730 +/- 20

Conifer

Aufrechter Flügel

1750/70

1775 +/- 20

Conifer

Amboss

?

1970 +/- 20

Oak

Bohrmachine

?

1900 +/- 20

Maple

Thalkircher Orgel

1630

1630 +/- 20

Oak

Cembalo von Patavini

1561

1514 +/- 20

Conifer

Bläser (Skulptur)

15° sec

1550 +/- 20

Oak (approx. 100 years younger)

Kastenmühle

1702

1700 +/- 50

Maple

Drechselbank

1886

1880 +/- 20

Maple

Drechselbank

1741

1730 +/- 20

Oak




II – J. Paul Getty Museum, Los Angeles
.

The high level of this museum’s laboratory is acknowledged the world over. Several wood samples without indications of age were put at our disposal. All the datings obtained spectroscopically coincided perfectly with those established by the American Museum, which recommended the spectroscopic method to AIC (American Institute for Conservation).
 

OBJECT

AGE PRESUMED
BY GETTY MUSEUM

SPECTROSCOPIC DATING AND CLASSIFICATION OF THE WOOD

Leleu table – sample A

1760

1740 +/- 15 Oak

Leleu table – sample B

1760

1750 +/- 15 Oak

Joubert Comode – sample B

1769

1750 +/- 12 Oak

Benneman cabinet – sample b

1788

1765 +/- 15 Oak

Marquetry donkey – sample A

1983

After 1960:  wood younger than 40 years cannot be precisely dated         

Marquetry donkey – sample B

1983

 


Public and private scientific institutes which use C14 and dendrochronological dating methods.

Although the new, simpler and cheaper method may be regarded as a rival by those who apply the above methods, during the 15 years of existence of spectroscopic dating no scientific evidence challenging its accuracy and reliability has ever been published. The only exception is an article which appeared in the magazine Restauro in 1998, persistently cited by the art market, but immediately confuted.
The lack of counterarguments is proof of the validity of the spectroscopic method.



Examples of the applicability of spectroscopic dating


paintings and frames


icons


beams


musical instruments


furniture


statues


clocks


weapons


African art


Oriental art

and many other possibilities


 

List of wood types which can be dated by IR spectroscopy
WOODS WHICH CAN BE DATED ACCURATELY
(with a margin of error of less than 10%)

Softwoods: fir, pine, Eurasian stone pine and most other softwoods
Hardwoods: linden, poplar, beech, maple and many similar hardwoods
Oriental woods: about 70 % of the woods normally used for Chinese sculptures
about 85% of the woods normally used for South-East Asian buddhas
African woods: about 85 % of the woods used for the sculptures and masks of the sub-Saharan tribes
WOODS WHICH CAN BE DATED ACCURATELY
(with a margin of error of between 10 and 20 %)
Softwoods: larch
Hardwoods: cherry, walnut (*), durmast oak (Quercus petraea), English oak (Quercus robur) and other locally growing oaks

(*) for this kind of wood 3 samples are needed, taken possibly from the lighter areas of the wood

Oriental woods: a number of woods commonly used for buddhas
African woods: a number of woods used for African sculptures and masks
WOODS WHICH CAN BE DATED WITH LESS ACCURACY
Softwoods: cedar
Hardwoods: pear wood, willow
Indonesian woods: a number of woods used for sculptures and masks by Oceanian tribes
WOODS WHICH UP TO NOW HAVE BEEN DIFFICULT OR IMPOSSIBLE TO DATE
Chestnut, ebony, mahogany, rosewood, boxwood and a number of Indonesian woods and other woods for which sufficient comparative data is still lacking. (For a number of these woods, which are often used as veneers, dating can be effected on the underlying wood).

Field of application of wood dating
A comparison with the radiocarbon 14C method:

Estimated age

Accuracy of the methods

Years IR Spectroscopy 14C (radiocarbon)

0 - 50
50 - 350
350 - 800
800 - 1000
>1000

Good
Good for known woods
Good for known woods
Good with > tolerance
Only indicative so far

Significant, but not certain*
Not applicable with certainty
Good with the known limitations
Good
Good

* The atomic bomb caused a significant increase in the formation of the 14C isotope


 

Instructions on how to take wood samples for dating


For dating purposes a sample of only a few milligrams of wood dust is needed, which has to be taken fairly deep in the wood and after having removed the first 2-3 mm of the surface. To take the samples use a normal electric drill having a milling-bit with a diameter of less than 3 mm (generally available in all hardware stores), possibly like the one shown in the picture, which produces a hole of the same dimensions as a woodworm hole. The wood powder must be gathered on a piece of white paper, which is to be folded carefully, sealed and mailed directly to the Museum laboratory. It is advisable to always take two samples for each piece of wood to be dated. In the case of furniture or objects composed of various wooden parts, take samples from at least two different sections.

Extra tips on how to take samples:

Prices to the public

Dating of 1 sample (only for tropical and equatorial woods) : 75  (US$ 100)
Dating of 2 samples from the same piece of wood : 100 Euro  (US$ 135)

Dating of furniture (2 samples taken from 2 different pieces of wood, for a total of 4 samples) : 150  (US$ 200)

Measurement results are communicated by mail or fax.

A plastic-coated certificate with a photo of the object can be issued only if the sample has been taken at the laboratory of the Museum or by an authorized person. Additional cost: 50,00 €

Museo d'Arte e Scienza  Tel: +39-02-72022488 - Fax: +39-02-72023156  E-mail: info@museoartescienza.com

For the USA you can contact an authorized person for the taken of wood samples

Mr John McGee - Southwest Ranches - FL - Phone: 954-6890497 - Cell: 954-801-4121 - jdmoga1@aol.com

 



The scientific laboratory of the "Museo d'Arte e Scienza" at the service of art
 

Gottfried Matthaes Foundation  - Milan
18 rooms and over 2.000 items on display

Via Q. Sella, 4 -20121 Milano -  Piazza Castello
Opening hours:
Mon-Fri: 10-18
Entrance: 8 - reduced 4
Guided tours:
(min. 10 people) 10

For
information: Tel:+390272022488. Fax:+390272023156

E-mail: info@museoartescienza.com

 

The Museum laboratory’s mission is to improve existing scientific methods and elaborate new methods for the ascertainment of the authenticity of art objects. The laboratory’s instruments and knowhow for the determining of authenticity are at the disposal of collectors, art experts, restorers, art galleries and museums. (The staff of the laboratory, who speak the main European languages, are at your disposal for any explanations). The laboratory of the Museo d'Arte e Scienza is a not-for-profit facility and is independent from every point of view.
 

Tests carried out by the laboratory:  
 

Spectroscopic dating and characterization of wooden objects

Microscopic tests on paintings, antique bronzes, excavated pottery etc.

Examination of underlying layers using infrared reflectography

Analyses of paint layers with a duroflexometer

Analyses with Wood’s light, UV and IR

 

Further analyses performed by the laboratory:
Spectroscopic chemical analyses on pigments, glues, encrustations, patinas, products of corrosion. Scientific, practical and instrumental tests of authenticity on: ivory, amber, archaeological glass, pigments, metals, stones,  carpets, tapestry, prints, books, clocks and watches, china.


 

The Founders and the permanent staff
of the Museo d’Arte e Scienza

   
 
   
 

Gottfried Matthaes
Founder and  President

Giovanna Cozzi Matthaes
Co-founder

 
 
     

Dott. Chim. Peter Matthaes
Lab. Director and CTU

Patrizia Matthaes
Administration
Silvia Mayer
Language and Communication
Dott. Avv. Martin Matthaes
Lawyer - International Law
 
 
Chiara Civardi
First lab assistant
Roberta Delmoro
Art Historian (Freelance)
Marta Cugnasca
Data processing
Sonia  Checchini
Conservation
       


 




Bibliography of articles in scientific periodicals

(selection)

- WAG Postprints AIC (American Institute for Conservation), Miami, 9 June 2002, 4 pages

- Scientific American (Italian edition “Le Scienze”) July 1998, 7 pages

- Scientific American  (French edition “Pour la Science”) July 1999, 6 pages

- Newton (Italy), June 2000, 7 pages.

-  Weltkunst (Germany) 1996, 5 articles

-  Restauro e Antiquariato (Istituto Geografico De Agostini) 1995, 20 fascicles.

To these must be added numerous articles in many periodicals around the world publishing detailed overall evaluations of the method and the Museum.

 

Published scientific commentaries
unfavourable toward spectroscopic dating

The method is based on the chemical changes undergone by wood with age. In trees, as in all living bodies, ageing is a genetically programmed process (DNA?).

These modifications due to the passage of time are inexplicably constant, identical both from one species to another and within the same species and exactly computable. A scientific and logical explanation for this is not yet possible.

The spectroscopic representation of the composition of wood and its changes over time, however, permit a very clear numerical rendering of the processes that have taken place. This data is obtained using samples of certain dating for the processing of samples to be dated.

The same goes for many other measurements in physics. We calculate earth’s gravity without knowing what the force of gravity really is, as we do with the presence of radio carbon, without knowing what factors increase or diminish its production in the atmosphere. We have to accept the fact that not all of nature’s processes can be explained.

We know of only one publication against the method published in the periodical Restauro in 1998: this article was based on a pseudo-scientific test which, in spite of valid refutations, is still upheld today for commercial reasons. A German scientific institute asked our Milan laboratory to analyse some samples of wood taken from a single tree trunk, but from different growth rings. Those who expected the spectroscopic method to show up the difference in age between the rings had not clearly understood either the method or its application in the art field. In absolute accordance with the spectroscopic method, in fact, all the samples gave the same result, i.e. the year the tree was felled. The article said, on the contrary, that this agreement between the ages was proof that spectroscopic dating does not work and is therefore to be refuted.

 (Relative documentation available on request)

 




APPENDIX

Advantages and limitations of the spectroscopic method

Advantages
of the ascertainment of authenticity for operators in the art sector
LIST of specific categories
Art museums

Collaboration between our laboratory and museums large and small the world over  is rather close.
More than 40% of all datings and identifications of the kind of wood were made for museums.
Every museum has significant objects of artistic and historic value, for which its own experts have doubts. A precise dating makes a clear evaluation easier.
However the low costs of the spectroscopic method are increasingly convincing curators to make an analysis of all the objects included in the inventory that have a doubtful classification. 
This inventory "cleaning" can be carried out in an absolutely anonymous way, because the museum restorer can take the wood samples following the instructions and make them dated without indicating the object.

Art experts and critics  

The very high percentage of copies and fakes to be found in most museums and collections goes to show that even experts can make mistakes.
The fact that the age of an art object can now be ascertained leaves a critic free to turn his mind wholly to the item's historical, artistic and commercial valuation. It is not indispensable that his valuation be accompanied by a scientific certificate. What is important, instead, is that the expert be convinced of his opinion and ready to answer for it in case of future scientific examinations.

Auction houses  

Auction catalogues with the dating of furniture, sculptures and painted panels are compiled by auction house experts (see "art experts"). Up to now no serious risks were run if the figures published were wrong. There were almost never legal proceedings with a clear verdict, because the judges had only the opinions of other experts to base themselves on. As in many other fields, in the art sector, too, increasing recourse will be had to the use of scientific data to establish the age of materials, binders, pigments, a specific craquelure, etc. and it will be possible to arrive at indisputable conclusions as far as the period of manufacture is concerned, but not to the attribution of the work to a particular artist. Scientific examinations for determining authenticity with computerized instruments cost about one or two per cent of the value of the examined object. They permit, however, a considerable rise in the price of an object of proven authenticity and constitute a safeguard against possible contestation.

Antique and art dealers  

This category of operators plays a pivotal role in the market and is the best informed about the quantities of copies and fakes in existence and the influence on the price of sale of certainty of authenticity.
At first sight the means for determining authenticity might appear to be a threat. In reality greater transparency and renewed confidence on the part of buyers offers advantages, not only for the dealer's reputation, but also from an economic point of view. At present, in fact, nearly all good objects are undervalued. The buyer's doubts and those, often, of the seller himself lead to a compromise price, often well below