www.spectroscopyforart.com                                            Last updating:  10/06/2009

Fond. Gottfried Matthaes
 

 

The spectroscopic Dating of Art Objects
in the Laboratory of the Museo d'Arte e Scienza, Milan

 

The scientific dating and classification of wood
current situation

The oldest – and still most commonly used – way 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.
So far the lack of suitable instruments has prevented absolute dating.

Halfway through the last century, two scientific methods (radiocarbon and dendrochronology) 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, around 1950, 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 irrespective of temperature, humidity, and place of origin.


Description of the method
 


How to take wood samples
 


Dating of ivory 


The scientific laboratory in Milan and its branch
 


Acknowledged value of the method and FAQ

 

 

  

 

 

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


 


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 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 right is only one example of the many characteristics of a spectrum.



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 is 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.


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

 

 

 
 


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 60% 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).
 
 
 
 
 
 

 

 

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:

  • Choose the parts to be dated with care: give preference to those which are more significant and best preserved, avoiding areas excessively damaged by woodworm or contaminated.

  • With statues, avoid the bases on which they stand, as these are often deeply corroded or contaminated.

  • With furniture, take samples preferably from the internal carrying structure, which is less subject to restoration or use of very seasoned wood. Avoid areas which may have been restored or substituted. Do not take samples from the veneers, which are not thick enough and are unsuitable.

  • With painted panels take samples from the back and not from the edges, one near the centre and the other near the edge.

  • If the article is made from walnut, it is advisable to take a third sample: ideally 2 from the light-coloured area (sapwood) and 1 from the dark-coloured area (heartwood) - no extra charge.

Prices to the public

Dating of 1 sample (only for tropical and equatorial woods) : €100  (US$130)
Dating of 2 samples from the same piece of wood : €150  (US$200)
 Dating of furniture (2 samples taken from 2 different pieces of wood, for a total of 4 samples) : €200  (US$260)

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 was taken at the laboratory of the Museum or by an authorized person. Additional cost: €50 (US$65)

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 taking of wood samples

Mr John McGee - Southwest Ranches - FL - Phone: 954-6890497 - Cell: 954-801-4121 - jdmoga1@aol.com
Cristian Rivera Onetto - Santiago Chile - Phone: (56-02)2478630 - altovitacura@gmail.com

 

 

 

Ivory
Elephant tusk or Plastic? 

 

Today it is possible to recognize authentic ivory
very easily

Musical instrument in ivory, Africa

Buddha temple, China (ivory)

Classification of the material

Sometimes, in addition to elephant tusks, the horns of other animals and some kinds of bone are inaccurately included in the category of ivory. Furthermore, increasingly perfect synthetic materials are being produced today which cannot be distinguished from ivory by their appearance alone.

All these materials consist of distinct molecules which can be recognized simply and clearly using spectrographic analysis (see fig. right) In order to perform the test, it is sufficient to extract a few milligrams of material (household drill) and mail the sample to a specialized laboratory.

Contacts:
in Milan: Dr. Peter Matthaes pr@museoartescienza.com
for Germany: Dr. Martin Matthaes mm@museoartescienza.com

Dating
 For authentic ivory it is possible to carry out a test to establish its age, but the procedure is more complicated because in order to take the sample it is necessary to bring or send the object to the Museum’s central laboratory in Milan or to the German branch where it will remain for at most half an hour.
 Ivory is characterized by its hardness, compactness, lustre and resilience, characteristics due to its chemical composition. The main element is represented by inorganic substances such as phosphate and calcium fluoride, the age of which is not measurable. But there are also organic substances present which undergo change with the passage of time according to biological laws. Analysis with infrared spectroscopy shows up the molecules present in the material permitting the ivory’s inorganic substances to be clearly distinguished from the organic ones. Analytical dating methods can thus be applied to the latter focusing on selected and measurable molecules.

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

PRICES: Classification of material: Euro 100 for an analysis. Dating of an ivory object: Euro 150.

For more information: www.IvoryAuthenticityandAge.com


 

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

Museo d'Arte e Scienza - Milan
 18 rooms and over 2,000 items on display
Via Q. Sella, 4 -20121 Milano -  Piazza Castello
Opening hours: Mon-Fri: 10:00-18:00
 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 know-how 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 non-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 laboratory in Germany, near Lindau (Lake Constance)
 
 Please contact Dr. Martin Matthaes
 +49 (0) 17676305108 – mm@museoartescienza.com

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


 

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

  

 

 

 

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.
 


Reliability and accuracy of the spectroscopic method

The need for a new method applicable also to single antiques

The validity of spectroscopic wood-dating method is acknowledged by scientific organizations, associations of restorers and, increasingly, famous museums worldwide. In the 15 years of its existence, our laboratory has performed over 20,000 dating analyses both for research purposes and on behalf of third parties, each measurement confirming the reliability of the method or contributing to its improvement.

 The quest 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 Museo d'Arte e Scienza. This situation was and continues to be common to most collectors of furniture, panel paintings, musical instruments, non-European art objects and so on.
 
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 and have been published.

 

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

 

Frequently Asked Questions (FAQ)

Question Answer
(see also "Description of the Method", a paper presented to the AIC meeting in Miami 2002) 
Is spectroscopy a destructive method?

Almost all scientific, manual and optical methods for the ascertainment of authenticity require samples of the material to be examined. These samples are normally very small, weighing only a few milligrams, and their volume cannot be compared to the volumes of material destroyed by insects, worms, corrosion, accidents etc.
Whereas "natural" damage is often considered  proof of the presumed age, the taking of samples for ascertaining the authenticity of an art object is considered an act of aggression against human culture. Obviously these conflicting standpoints are not based on cultural considerations.
Is there any sense in determining age when use could have been made of wood that was already old?

The use of old wood can be detected quickly and easily by comparing the spectroscopic results of the outer layer of the wood with those of wood taken from inside the object.
The surface of an object undergoes a much stronger chemical transformation because it is exposed to daylight, humidity and impurities in the air. If objects are fakes, the results of the two analyses are more or less identical, depending on when they were made.

Is spectroscopic analysis inaccurate because chemical changes depend on the humidity and temperature of the environment?

It is normal to pose this kind of doubt. But wood is a very complex organic material known for its extraordinary resistance to water and heat.
The ability of a part of the wood material to withstand atmospheric agents has been demonstrated, moreover, by amber and by shipwrecks thousands of years old found at the bottom of the sea. Amber is a resin which, even after spending more than 200 million years in sea and river-beds or moist earth, looks very much like fresh resin. The timbers of ancient ships have also maintained the shape and appearance of old wood.
Measurements and comparisons of the spectra of old and young material taken from the abovementioned examples have shown that there are wood molecules whose behaviour is absolutely unrelated to external environmental factors.
These are the molecules which are used for spectroscopic dating.

Can the results of age dating be intentionally altered through manipulation of the wood?

The possibility that material has been manipulated must always be borne in mind whenever determining the authenticity of an object, and was our chief concern during early experiments with spectroscopic dating.
Also in the case of spectroscopy, the wood material proved to be extremely resistant to heat and moisture. This characteristic has been known and documented for a long time (see for example "Holztechnologie" 23, 1982).
Repeated measurements taken over the years by the laboratory to verify the influence of humidity and temperatures of up to 180° C have demonstrated that treatment of the wood aimed at accelerating its ageing does not significantly affect the age of the molecules selected for measurement.
Temperatures of over 180° C modify the entire spectrum.

Is the Milan laboratory  sufficiently well equipped?

The Matthaes Foundation is in a position to acquire the most modern instruments and apply the most suitable methods.
The laboratory's current equipment permits the achievement of optimum results.
Are spectroscopic dating prices  too low for scientific examinations?

Spectroscopic dating is carried out with instruments which are basic equipment for the chemical industry and the health and research sectors.
The greatest costs were incurred during the development of the method dedicated for many years to the spectroscopic identification of the many different wood types and molecules or groups of molecules suitable for dating purposes.
These costs were borne by the Matthaes Foundation.
Today a spectroscopic dating costs about as much as a normal medical examination.

Are there known cases of erroneous measurements?

Statistics tell us that about 60% of the antiques existing in the world are not authentic. Consequently 60% of dating should statistically not correspond to the presumed age. The fault is often attributed to the method.

What legal value do scientific datings have?

All the countries in the Western world have laws punishing the sale of fakes and forgeries. Courts rarely pronounce judgements, however, since so far judges have only had expert opinions to base themselves on. The reliability of spectroscopic dating allows judges to give a clear sentence.

 

 

OTHER SITES OF THE MUSEUM OF ART AND SCIENCE: 
 

www.MuseoArteScienza.com - Sections of the "Museo d'Arte e Scienza": 6 rooms dedicated to the ascertainment of authenticity in art and antiques, 5 rooms on Leonardo da Vinci's "Treatise on Painting" and his activities in Milan, 5 rooms dedicated to African Art and Buddhist Art, 2 Scientific Laboratories.

www.LeonardoDaVinciMilano.com - Two permanent exhibitions: "Leonardo Citizen of Milan" and  "Appreciating Art through the Eyes of Leonardo" from his "Treatise on Painting".

www.AuthenticAfricanBronzesandCeramics.com -  Dedicated to the authenticity of African artworks in bronze, stone and pottery. The scientific laboratory of the Museo d’Arte e Scienza has developed valid methods for telling authentic African objects from copies and fakes.

www.ArtAndScienceHandbook.com - The most complete and scientifically valid guide to ascertaining the authenticity of European and non-European antiques on an objective basis (540 pages and more than 2,000 colour illustrations in 3 volumes and 3 languages).

www.Paintingsauthenticity.com - Information about the authenticity of modern paintings and antique paintings.

www.AntiqueFurnitureAuthenticity.com - A list of possible methods for determining the authenticity of furniture based on objective factors.

www.Excavatedartauthenticity.com - "A list of all the possible ways of determining, on the basis of objective factors, the authenticity of excavated pottery, glass or bronze items from Southern Italy, the Mediterranean Basin, China and South America.".

www.AfricanArtAuthenticity.com - "Art and Life in Black Africa", The African Art didactic section of the Museum (5 rooms and over 350 objects).  

www.Matthaes.org  - The history of the G. Matthaes Foundation from the opening of the painting school in Dresden in 1906 up to the Museum "Arte e Scienza" in Milan.

www.CopiesAndFakesInArt.com - Ample further descriptions for ascertaining authenticity in art in the individual fields of antiques.

www.IvoryAuthenticityAndAge.com - Ivory, bone and horn can now be spectroscopically dated and accurately identified.

www.LeonardoTeacherofPaintinginMilan.com - An abridged and illustrated edition of the “Treatise on Painting”.

JOIN OUR MAILING LIST TO RECEIVE OUR NEWS!

 

analisi spettroscopica datazione oggetti