Part I – African bronze Objects
Methods and techniques to distinguish between authentic pieces, copies and fakes
 

The production of bronzes, unlike items in wood, calls for the use of costly materials and specific technical know-how. Such pieces are rare and their style generally closer to Western tastes. It is calculated, however, that over 80% of all large-sized and very decorative bronzes are copies or fakes.

There does not exist any scientific method for the absolute dating of metals in general and, therefore, for African bronzes in particular. A good scientific laboratory with wide experience in the sector can, however, identify characteristics pointing to authenticity. Valid proof on the basis of which it can be affirmed with great certainty that an artwork in bronze is “authentic” – in the sense that it is antique – is provided only by a chemical analysis of the patina, or the layer of corrosion products which has formed over the object’s entire surface. A few milligrams of material are sufficient for this purpose. Spectroscopic analysis, carried out by expert personnel, can distinguish definitively between an authentic patina made up of bronze alloy corrosion products and a fake patina made from paints, earths and synthetic materials. Ample description on the following pages.

A selection of African bronzes
analysed by the Milan laboratory

Bronze is an alloy of copper combined with other metals in order to make it more fusible or improve its mechanical and optical properties. Given its relatively low melting point, bronze is one of the oldest metal alloys used by man. Bronzes constitute therefore, together with ceramics, the oldest objects to be found on the antiques market.

Bronzes have always been produced by casting. Whatever an artist could do in antiquity with relatively primitive tools can be easily copied today by a technician with the sophisticated means and know-how at his disposal. Nearly all bronze statuary and even a number of objects of smaller dimensions were created by the lost-wax method. The clay model inside the statue testifies to the fact that the statue is a one-off and not an industrial copy.

Bronze has always been a rare and costly material in Africa. For this reason the wall thickness of statues was kept as small as possible. As a result the outer surface has roughly the same contours as the inner surface (photo Ife head). Copies and fakes have an almost smooth inner surface. In the case of large-scale Benin heads, the rule of thumb is that the smaller the metal wall thickness, the more antique the object.
 

Ife Mask
authentic

Benin head copy

← Inside →

The chemical analysis of bronzes alone provides little help in clearing up doubts about authenticity. In the last decades, research institutes have carried out thousands of chemical analyses on old and antique bronzes so that today there are statistics available to everyone indicating the typical composition of alloys in determined periods and areas of production. A good faker is however familiar with this data which therefore cannot constitute proof.

Antique bronze patinas

The principal metal in the bronze alloy is copper, which is also the least stable component of this alloy. In the presence of humidity and electric field, as is always the case underground and in the air, the copper comes to the surface and tends to oxidize to cuprite (a brick red colour). On coming into contact with the acids and other compounds occurring in the earth or in the air, this cuprite is converted into salts which, as time passes, turn into crystals of various colours.
The principal salts are:    green in colour            carbonates and sulphates
                                      blue in colour               carbonates and nitrates
                                      black in colour             sulphurs

carbonate

sulphate

fake

As time passes the corrosion patina may become overlaid with organic and inorganic matter which, in most cases, is due to the so-called “sacrificial patina” formed during the cult (Photo 1). And here again it is spectroscopic analysis which can answer the question “true or false?”.

photo 1

photo 2

The formation of thick encrustations, such as those typical of Greek and Roman archaeological finds, is possible also in Africa, on objects which may be as old as about a thousand years. (Photo 2)
Even the black patina covering most large-sized Benin bronzes offers decisive proof regarding age and authenticity. At the present state of research six types of these patinas have been identified which are measurable and therefore useful for determining authenticity.
Fake encrustations, created with glues, cement and paints, produce totally different spectra, revealing the falsity of the artefact presumed to be antique.

These evident characteristics, which are impossible to imitate and can be identified with simple scientific tests, thus represent the only certain and indisputable proof of the authenticity of bronzes. For a first test to detect fakes by spectroscopic analysis of the patina, it is sufficient to remove a few milligrams of the layer of corrosion products to be submitted to an experienced laboratory. One of the specialties of the laboratory of the Museo d’Arte e Scienza in Milan is large Ife and Benin bronzes. For detailed information about the activity of the scientific laboratory of the Museum on behalf of collectors, museums etc. see www.africanartauthenticity.com

Naked-eye examination of the patina
 

Outer surface

Photo 1 – Ife mask

Enlarged under the microscope,
the corrosion patina reveals
its compatibility with an age of over 500 years.
The protective layer has been removed

photo 1

Photo 2 – Ife head

Enlarged under the microscope,
the corrosion patina reveals
its compatibility with an age of over 200 years

Objects 1 and 2 are property of the Museum

photo 2

photo 3

photo 4 –
Copy of a Benin head, 
about 50 years 

photo 5 -
Enlargement of the finished and uncorroded outer surface

photo 6 -
Enlargement of the unfinished and uncorroded inner surface

No physical method exists for measuring the age of bronze. The elements constituting bronze are as old as the Earth itself. Lead, traces of which may be found in bronze, has radioactive isotopes. But the time it takes this isotope to decay has not permitted measurable results to be obtained. In the case of archaeological finds it is possible, in exceptional cases, to measure remains – if any – of the ceramic core using the thermoluminescence technique. In must be borne in mind, however, that the bronze wall absorbs radiation from the earth, preventing it from reaching the core.
 

Stylistic features
 

Every culture and stylistic trend prescribes precise forms, proportions and ornamental motifs for an art object, so that being able to identify the period to which a style belongs makes it possible to calculate an approximate date of production. But since every style in all its forms of expression could be copied by skilled artists, any opinion based on style alone must be corroborated by other evidence. Well over half of the countless copies of high quality bronze statuary and one-off pieces made using the lost-wax technique filling collections and private homes date from the second half of the 19^th century and the first decades of the 20^th. Unrefined fakes in solid bronze are produced now for the tourist market using quasi-industrial materials and techniques.

Handicraft

An important and significant clue to age is whether the artefact was made by hand or produced in series. The African craftsman who cast the bronze had plenty of time to execute details with great care and this can be seen in the expression of faces and decorative elements.

Famous and precious are the bronze heads and, from the Benin period, also the large bronze plaques with figures. Whilst the Ife style died out towards the XV century, the production of Benin bronzes probably continued until the middle of the 19th century.
The evaluation of the bronzes will certainly differ according to age and style. According to the criteria adopted by our laboratory, all Ife and Benin bronzes produced after 1898 (when Benin city was conquered by the British) are judged to be copies and, if found to have signs of artificial ageing, as fakes. Almost all authentic Benin plaques have areas where the metal is missing. This is hardly ever due to damage or corrosion, but to the fact that in the casting process the molten metal did not reach the parts in question. A number of inauthentic monumental Benin bronzes, possessing a ceramic core, have a certain amount of artistic and commercial value and should not be simply dismissed as fakes. Many of them are technically excellent one-offs produced in the second half of the 19th century by skilled craftsmen.

All objects illustrated in this website belong to the G. Matthaes collections,
Museo d’Arte e Scienza. (Exception page 2)

Stones were formed a long time ago during the cooling of our planet's surface through the sedimentation of rivers and seas. Their age thus corresponds to that of the Earth itself and it is therefore utterly senseless to try to date an antique stone object by measuring the age of the material.

In order to identify the periods to which authentic objects belong and evaluate their artistic worth, it is necessary to be acquainted with the styles characterizing the different historical periods, something that is not yet possible in the case of African art. A knowledge of these characteristics serves also to recognize fakes when they are not in keeping with the purported or scientifically established age.

We know of figures that may be older than
500 or even 1000 years

Since the interior of stone objects cannot be altered either by climatic or other influences, an evaluation of authenticity can be based only on the changes wrought by time on the surface of the stone.

Enlargement 10x

Enlargement 30x

Petrified lichens found on the figure to the left
(Enlargement 30x)

The signs illustrated above can be copied or faked, but only the human eye is deceived. When optically enlarged, imitations are revealed for what they are. If the encrustations are genuine, on the other hand, they constitute certain proof of authenticity. Further spectroscopic analyses allow many other aspects to be investigated.

This type of stone is crystalline, calcareous and more subject to environmental corrosion and wear than any other stone.

Objects in soapstone develop a very particular patina in the points where they are often touched. The grease and acids in the skin enter into the pores of the stone and cause a kind of saponification reaction. This saponification gives the stone translucence and a soft, warm colour, very different from the matt, opaque surface of the untouched or broken parts. A magnifying glass reveals a crystalline but very shiny surface, a sign that it has been repeatedly rubbed with hands, reorienting the crystals which all end up lying in the same direction, creating a very attractive mirror effect.

The best known African figures carved in stone come from the regions inhabited by the Kissi, the Mende and the Sherbro. These are small squatting figures believed to be very old. They are often known also as nomoli or pomta and are nearly always uncovered in tilled land. In many cases residues of earth and roots can still be found, others were kept on domestic altars and their patina is formed as a result of the attentions of their owners. According to local traditions, these figures were meant to be used to protect the crop. It sometimes occurred that a similar figure was damaged as punishment for a poor harvest. As with many other religious creeds, the owner does not turn on the principal image. It is the eyes and nose of the minor figures that take the brunt and this circumstance likewise represents a good indication of authenticity.
 

African sculptures were generally exposed to a great deal of rain. Washing a part of the surface, therefore, cannot damage them in any way. On the contrary, a wet cloth can be very useful for ascertaining authenticity.

As far as other African stone figures are concerned, few studies have been carried out. Every now and then interesting finds are made, but it is not always possible for the present to interpret their meaning.

Part III – African Pottery
 

Every collection having as its theme the development of a people over the entire span of its history must necessarily include its terracotta pottery. Our knowledge of African pottery goes back thousands of years. At the time of the Romans (from the 1st to the 5th century) North Africa was the greatest ceramic-making centre in the Mediterranean. Africa covers an extremely vast territory and excavations have begun only recently. Our knowledge of African pottery is therefore fragmentary and enormous treasures are still hidden in the earth. Some cultures and styles have already been identified and found their way to the market, like the Nok clay figurines or those of the hinterland of the Niger delta.

There are a good number of rules which can be applied to excavated pottery of every type and provenance, described in our website www.excavatedartauthenticity.com. With the exception of Nok clayware, most of the African artefacts excavated today are less than a thousand years old. There has rarely been time for plant roots present in the soil to leave their petrified traces on the terracotta. The dried roots often found attached to the ceramic surface are, instead, a sure indication of authenticity.

Nok terracotta figures are among the most ancient, sought-after and costly – and thus amongst the most faked – artworks of Black Africa. The first Nok heads were discovered  in 1928 in the vicinity of the village of Nok in North Central Nigeria. The find was made in dry tin mine galleries, for which reason they generally showed few signs of contact with the earth. The ascertainment of their authenticity is therefore not based on scientific tests so much as on a long and intense experience in examining figures of this kind.
 

A significant example of this is comparing the enlarged images of the surface of the head of an authentic figure with those of a fake: whilst in the former the colours have faded and the edges softened, in the latter – shown below – the colours are still vivid and the edges sharp. Encrustations are visible only under a  microscope.

← Authentic

← Inauthentic

Pottery of the Niger Inland Delta

Djenne figures were covered with a red slip similar to the Roman terra sigillata ware. Traces of this colour are a precious clue to the authenticity of the object.

3

2                                         2a

Along the same river a considerable number of figures with cylindrical bodies are being found. The styles have provisionally taken on the names of the places of their discovery, such as Bambara, Bamako and Bakoni. These figures are believed to have been made between the 8th and 16th centuries. (3a - 3b)

3a                     3b

4

Finds were often unearthed on the banks of a river, and therefore in a humid climate, inside clay receptacles. They do not present many encrustations, but most have a rough surface covered with numerous fragments of roots, clearly demonstrating their authenticity. Some of these figures show rests of a bleached slip. (4)

Terracotta heads of the peoples of Ghana

These heads are popular with collectors on account of their generally pleasant expression, unlike those in bronze. Presumably these ceramic heads date back to a period comprised between the 17th and the 19th centuries. There is a large multitude of facial shapes and expressions.
 

The ceramic body may also vary from very smooth to very raw and rough. The relatively low firing temperature, however, produces a fairly soft body with little resistance to mechanical damage, a factor which, with thorough experience and possibly a microscope, permits recently-made pieces to be readily distinguished from antique finds.

Few people know !

On the lower floor of the Museum it is still possible to see the secret tunnel, built in Leonardo’s day, which led to the Sforzesco Castle.

OTHER  SITES OF THE MUSEUM OF ART AND SCIENCE: 
 

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