Scientific analysis of a painting makes it possible to examine the materials it is composed of in order to shed light on its history, state of preservation, and authenticity. Today, it is an invaluable tool for restorers, curators, collectors, experts, and professionals in the art market.

At CIRAM, this approach is based on complementary methods: dating of the supports, chemical analysis of pigments, binders, and varnishes, as well as various scientific imaging techniques. Cross-referencing these results helps to better understand the creation of a work, detect potential restorations or inconsistencies, and provide objective elements for its appraisal.

The Main Methods of Scientific Analysis of Paintings

To study a painting, several complementary approaches are used. Some allow researchers to date the materials, while others help identify their composition or reveal elements invisible to the naked eye. These methods are chosen based on the nature of the artwork and the questions being addressed.

Dating the Media

Dating the supports makes it possible to estimate the age of the organic materials that make up a painting, such as linen or hemp canvas, wood, paper, or cardboard. Performed primarily using the carbon-14 method, this process provides a valuable chronological reference for verifying the consistency between the materials used and the presumed period of the work’s creation. However, this analysis does not directly date the paint or the creation of the work, but rather the moment when the organic material ceased to be alive—for example, when the flax was harvested or the tree used as a support was felled. The results should be interpreted in conjunction with other scientific and historical investigations.

The carbon-14 method is presented in more detail in our article on carbon-14 dating of paintings.

Chemical Analyses

Chemical analyses make it possible to identify the composition of the various materials that make up the paint layer. These analyses focus in particular on pigments, binders, varnishes, and mineral fillers. They help verify whether the materials are consistent with the work’s presumed period of creation, detect certain restorations, and provide additional information to support dating and scientific imaging.

The methods for identifying pigments, binders, and varnishes are detailed in our article on the chemical analysis of paintings.

Scientific imaging techniques

Scientific imaging techniques provide valuable information about a painting. They allow for the investigation of all layers of a painting, from the varnish, to the support, including the preparatory drawing, the paint layers, pentimenti, repainting, and any restorations. Natural light, ultraviolet, infrared, and X-ray radiography, discover all the imaging techniques for the analysis of paintings.

These methods are totally non-destructive. Discover why this type of analysis is preferred for works of art.

Visible light imaging

We distinguish between three different types of visible light examination:

• Visible light photography: produced under specific conditions, these images correspond to classic photography;
• Grazing light photography: this type of photography reveals the state of conservation of the work's surface. Our scientists illuminate the work with a focused beam of light forming a 15° angle with its surface. This technique makes it possible to detect alterations to the paint layer (lifting, blistering, cracking, etc.), deformations of the support (poor tension of the canvas, cracks or joining of the boards) and alterations such as tears, scratches or dents. Grazing light also provides clues to the painter's techniques and style.
• Transmitted light photography: this is used to observe the reverse side of canvas or paper paintings. With this method, our scientists can detect holes and tears, as well as alterations in the paint layers.

Ultraviolet (UV) radiation

Ultraviolet (UV) radiation lies outside the visible spectrum, and is divided into near UV (380nm to 200nm) and extreme UV (200nm to 10nm).

UV imaging enables the surface layer of the painting to be explored. It uses the fluorescence properties of the varnish, which are more or less intense depending on its composition and alteration. Overpainting on varnish or restorations can be easily identified.

Important: in the absence of varnish, some natural pigments may emit a colored fluorescence, a fact to be taken into account to avoid misinterpretation.

Infrared (IR) radiation

Infrared radiation ranges from 780 nm to 5 mm, beyond the visible spectrum but on the opposite side of the ultraviolet spectrum. The CIRAM laboratories use what is known as “warm” light, which falls within the near-infrared range. This makes it possible to measure the absorption of infrared radiation by the materials that make up the paint layers.

Thanks to infrared reflectography, our scientists can reveal preparatory drawings, repentirs and repaints. This imaging method produces grayscale images corresponding to varying degrees of interaction with the initial radiation.

X-ray radiography

X-ray radiography captures an image of the internal structure of a painting. The X-ray beam is directed onto the painting, and the X-rays transmitted are observed as a function of the selective absorption of the material. This absorption is linked to two parameters:

• Through thickness
• The density of the materials making up the object.

With this examination, it is possible to identify the damage caused by the passage of time, as well as anthropic actions of all kinds from the creation of the work to the present day. It is also possible to identify repaints and repentirs thanks to contrasts in material density.

Radiography is one of the major imaging techniques. Discover how it reveals the hidden history of a painting.

The equipment used by CIRAM scientists

Visible-light imaging is performed using a 10-megapixel SAMSUNG® EX2F digital camera equipped with a 24–80 mm f/1.4–2.7 lens.

Infrared reflectography imaging is carried out between 900 nm and 1700 nm using an OSIRIS HD Infra Rouge Opus Instruments Ltd® 16-megapixel digital acquisition system. The equipment used for X-ray radiography is portable, comprising a mano-medical HF 1060 high-frequency X-ray generator, a FUJI D EVO II digital acquisition sensor with automatic triggering and Bluetooth transmission (FDR D-EVO, 35 x 43 cm), and a computer for generator control and image processing (OSIRIX software). The acceleration voltages used are 40 kV, 50 kV and 75 kV. Parameters were controlled using Fujifilm® software.

Using this state-of-the-art equipment, CIRAM’s laboratories date and analyze your paintings, sculptures, and ethnographic and archaeological artifacts.

Richard Cheret

Richard holds a master’s degree in chemistry (1999) and a master’s degree in the physics of archaeomaterials (2000) from the University of Bordeaux. In 2005, he co-founded the CIRAM laboratory with Olivier Bobin, and today serves as its co-manager and sales director.

Whether you are an art market professional, a collector, or simply an enthusiast, knowing how to recognize bronze and differentiate it from brass is an essential skill.

Indeed, accurately identifying the material of a sculpture or an ancient object is a crucial step. This skill directly influences the ability to appraise, conserve, and authenticate works. As the art market sees an increase in sophisticated forgeries, being able to recognize a genuine art bronze becomes an asset that is as much financial as it is heritage-related or legal.

In the field, misjudgments are quite frequent: altered patinas, undocumented restorations, hybrid objects mixing old and contemporary... Faced with these uncertainties, the experienced eye of experts is not always enough. Hence the growing interest in scientific analyses, which today offer precise and reliable answers to forgeries.

Identifying bronze: visual cues and empirical methods

In the course of their work, art professionals are confronted with a well-known situation: they have to decide quickly on the nature of a metal, often without immediate scientific analysis equipment. In this context, visual cues and empirical tests are the first tools available, but they require expert reading and great caution.

The visible differences between bronze and brass: what can you really see with the naked eye?

Bronze is an alloy of copper and tin, while brass is an alloy of copper and zinc. This difference in composition explains their distinct physical properties and appearance.

This difference in composition leads to a number of notable differences that are easily identifiable by specialists in metal works of art.

Common pitfalls: why visual analysis can be misleading

Appearances are often deceptive. Chemically burnished or patinated brass can simulate the hue of an antique bronze. Many industrial or decorative reproductions, for example, have been deliberately oxidized to imitate historic sculptures.

Another possible pitfall is hybrid objects, restored or completed over time with different metals. These additions, often invisible to the naked eye, considerably complicate identification.

Finally, modern counterfeits are made using sophisticated alloys and artificial aging techniques. In these cases, even an expert eye cannot conclude without scientific analysis.

These frequent cases, observed while studying the most accomplished counterfeits, show how empirical observation, though valuable, must today be complemented by scientific examinations carried out by specialized laboratories capable of recognizing bronze from brass.

Chemical composition and structure: laboratory analysis to distinguish bronze from brass

As we have seen, visual clues quickly reach their limits. To counter this problem, art professionals and collectors can call upon scientific analysis to validate the composition of works. Thanks to material characterization technologies, it is thus possible to precisely identify the composition, structure, and origin of an alloy. These methods offer art market professionals tangible and verifiable evidence for valuation.

Alloy analysis: the elemental signature of bronze and brass

As a reminder, there is a difference in chemical composition:

It is important to remember that each alloy has a unique elemental signature. The main techniques used to reveal it are :

These scientific metal analysis techniques make it possible to identify the nature of the alloy, but also to obtain chronological and geographical clues. Certain metallic profiles are characteristic of a period (Early Bronze Age, Renaissance, 19^th century) or a region (European, Asian, African alloys).

In this way, composition becomes a marker of authenticity, capable of revealing modern substitutions or inconsistencies in the supposed dating of an object.

Microstructural studies and corrosion: how to differentiate metals in depth

Observing the microstructure of metals provides a complementary reading. Using metallographic microscopy or electron microscopy (SEM/MEB), the laboratory analyzes grain size and shape, the presence of inclusions or cracks, and the nature of corrosion layers.

Observing corrosion to detect fakes

The differences in corrosion are particularly revealing:

• Old bronze develops a thick, heterogeneous patina of copper oxides and carbonates, tin oxides and deep-rooted lead salts.
  
• Brass, which is more sensitive to dezincification, often shows pinkish or greenish surface alterations, easily simulated by artificial processes.

In the laboratory, these signs are interpreted to distinguish natural corrosion (authentic ageing) from artificial patina (simulated ageing).

Complementary techniques, such as the CAST method (a comparative analysis of the alloy surface) or thermoluminescence dating of the cast iron core, allow us to go even further.

Taken together, these examinations provide a comprehensive, scientifically sound diagnosis that far exceeds the limits of a visual appraisal by even the most expert bronze object specialist.

When should a bronze object be analyzed?

While the value of bronze objects is conditioned by the authenticity and traceability of the works, recourse to a laboratory specializing in art is essential. The identification of an alloy then becomes part of a true scientific expertise process, combining chemistry, physics, and metallographic observation.

To differentiate between antique bronze and brass, CIRAM scientists mobilize :

• optical microscopy, for initial non-destructive characterization
  
• the Metallography and SEM-EDS, for a complete structural and chemical analysis
  
• thermoluminescence tests and technological correlations (if necessary), to confirm period or origin.

These results are then presented in a detailed, legally usable scientific report to guarantee the reliability and transparency of the analysis (and the work).

Conclusion

Visual cues often help guide an initial diagnosis. However, they are not always sufficient to distinguish with certainty between bronze and brass, especially in the presence of restorations, artificial patinas, or counterfeits.

Scientific analyses then provide objective data on the alloy's composition, its microstructure, and its state of preservation. They provide valuable support for the authentication, restoration, or enhancement of works.

Do you wish to authenticate a bronze object or verify the nature of an alloy? CIRAM's teams will guide you in choosing the most suitable analyses to obtain reliable and scientifically documented results.

Olivier Bobin

Olivier holds a master’s degree in chemistry (1996) and a Ph.D. in Archaeomaterials Physics (2001) from the University of Bordeaux. In 2005, he co-founded the CIRAM laboratory with Richard Chéret, and today serves as its co-director and scientific director.

Among art market professionals, a signature—no matter how discreet—can add thousands, or even millions, of euros to the value of a painting. However, a signature alone does not guarantee a work’s authenticity. It may have been forged, added after the painting was completed, or altered during restoration.

Faced with increasingly inventive counterfeiters, experts can spot certain clues with the naked eye, but only scientific analysis can verify if a signature is consistent with the materials, the execution technique, and the period of the painting's creation.

In this article, discover what clues may serve as warning signs, what analyses can be used to study a signature, and why it is essential to cross-reference these results with an examination of the work as a whole.

What are some signs that can help you spot a forged signature?

An unusual signature does not necessarily mean that the painting is a fake. Some artists evolved their signature over their careers or signed certain works several years after they were created. Conversely, a perfectly imitated signature can hide a forgery. This is why the expert must always analyze the signature in conjunction with the materials, the execution technique, and the history of the work.

Warning signs that an expert can spot with the naked eye

When a professional examines a signature, there are several visual criteria that may indicate forgery. One of the first reflexes is to compare the suspect signature with certified copies by the same artist. This comparative analysis focuses on elements as precise as the shape of the letters, the regularity of the gesture, the pressure of the stroke or the use of the medium (oil, ink, graphite).

The expert will also observe the consistency between the signature and the pictorial layer: is it located below or above the varnish? Is it in harmony with the natural wear of the support? A signature that seems to "float" on the surface, or whose colors are not found anywhere else on the canvas, is a warning sign.

Finally, the composition as a whole must be studied in terms of stylistic chronology: does the signature correspond to the work's supposed period? Are the materials used compatible with those available at the time? These analyses can sometimes reveal inconsistencies that are striking to the naked eye.

The limits of traditional methods in the face of modern painting forgery

Today, visual expertise faces its own limits in the face of advances in forgery techniques. Some counterfeiters use sophisticated processes: stencilling from authentic signatures, meticulous imitation of the gesture, insertion of ancient pigments to cover their tracks. A masterpiece of craftsmanship.

Deception sometimes reaches such a level that restorers or forgers add a signature during a restoration to pass off an anonymous work as a signed painting. Even the most seasoned expert then encounters difficulties when counterfeiters reuse period materials, such as old canvases, original frames, or historical pigments, to mask their tracks.

This is why art professionals are increasingly turning to an integrated approach, combining sensitive observation with scientific tools such as multispectral imaging or chemical analysis of paintings. Rigorous and reliable expertise can no longer do without scientific evidence capable of confirming or refuting what the eye perceives.

The Role of Scientific Techniques in Analyzing a Signature on a Painting

Science can compensate for the limitations of visual examination. Thanks to high-performance analysis tools, it is now possible to precisely characterize the materials making up a signature, and to place them in their temporal and pictorial context.

Study of signature materials: pigments, binders, inks

Like the rest of the painting, a signature contains identifiable materials: ink, oil paint, acrylic, oil pastel, or even grease pencil. Scientists can analyze their composition and compare it to that of other materials present on the artwork. Chemical analysis allows for the detection of these components with fine precision, thanks to techniques such as infrared spectrometry (FTIR), Raman spectrometry, or X-ray fluorescence (XRF).

These methods make it possible to compare the pigments and binders used for the signature with those used for the rest of the pictorial composition. A discrepancy in chemical formulation, such as ink containing synthetic dyes that appeared after the artist's supposed death, will reveal a proven indication of forgery. Similarly, the use of pigments incompatible with the presumed period or absent from the artist's usual palette may reveal a later addition or forgery.

In-depth observation with microscopy and scientific imaging

It is also essential to understand when signatures incorporated into older works were applied. To this end, stratigraphic analysis is crucial for visualizing the different layers of material and the chronological order in which they were applied. Under an electron or optical microscope, it is possible to determine whether the signature lies on top of a layer of varnish, which would indicate that it was added after the work was completed.

UV (ultraviolet), IR (infrared), and X-ray imaging, on the other hand, reveal what is invisible to the naked eye. UV, for example, can reveal abnormal fluorescence around a repainted signature. Infrared imaging allows us to see beneath the original paint layer in search of a signature that has been erased, altered, or added later. Finally, X-ray imaging identifies material densities: any mechanical engraving or foreign material stands out immediately.

The use of these analytical techniques makes it possible to cross-reference important physical data. It becomes possible to identify not only the chemical nature of a signature, but also its chronology and its formal relationship to the painting. This provides crucial support for any rigorous expert analysis.

When to call an analysis laboratory?

When a signature raises doubt, scientific analysis can provide objective elements that visual observation alone cannot. By studying the composition of pigments or inks, their position in the different layers of the painting, and their consistency with the work's materials, a specialized laboratory can determine whether the signature is contemporary with the creation of the painting or if it is the result of a later addition.

At CIRAM, this approach combines scientific imaging, physico-chemical analyses, and materials study to place the signature within its creation context. The results are presented in a clear and documented analysis report, usable for expert appraisals, sales, insurance, or litigation.

Richard Cheret

Richard holds a master’s degree in chemistry (1999) and a master’s degree in the physics of archaeomaterials (2000) from the University of Bordeaux. In 2005, he co-founded the CIRAM laboratory with Olivier Bobin, and today serves as its co-manager and sales director.

For collectors and art market professionals, authenticating an antique bronze is a real issue of value, confidence and heritage preservation. With the rise of modern reproductions, often produced with remarkable skill, professionals can no longer rely on visual expertise or intuition, however accurate.

To avoid these risks, it is imperative to know how to verify the authenticity of a bronze. This now requires a rigorous approach, combining historical knowledge with cutting-edge scientific analysis. Art specialists generally focus on style, weight and patina to evaluate a piece, but only a specialized laboratory can validate authenticity.

In this article, we'll explore the physical and traditional criteria for identifying a bronze. We'll then look at how scientific analysis techniques offer concrete, datable and documentable proof. Finally, we will highlight the key role played by laboratories like CIRAM in supporting art professionals, between expertise, security and enhancement of works.

Why recognizing an authentic bronze can no longer rely solely on the expert's eye

The art market is a system in which each piece involves significant heritage and financial value. Thus, the identification of a bronze cannot be limited to intuition or the experience of an expert, however respectable it may be.

Visual clues to antique bronze: patina, color, weight, sonority

The natural patina that has developed slowly over time offers shades of verdigris, deep browns and golden highlights, rarely matched by artificial processes.

The weight and density of the object are also useful indicators. An antique bronze generally has a density of around 8,600 kg/m³. If a piece weighs too little for its volume, this is a sign that a poorer alloy or a substitute material (regal, resin) has been used to make it. The magnet test (albeit empirical) is sometimes used to rule out modern ferrous alloys. Finally, the clearer, more crystalline sound of a genuine bronze, obtained by striking the metal, can offer a further indication of a counterfeit.

The limits of visual analysis in the face of modern copies and restorations

However, the methods described above have major limitations. Today's market is flooded with sophisticated reproductions, sometimes cast from period molds, with an artificial patina applied by specialized craftsmen. Even old restorations can be confusing, as they may mix original elements with materials added later.

Even experts can't rely solely on their own eyes or experience when faced with this level of uncertainty. To recognize an antique bronze with accuracy, it becomes necessary to resort to reliable scientific analysis, capable of accurately determining the chemical composition, the internal structure of the metal, or even the origin of corrosion. These elements are indispensable and constitute tangible proof to authenticate an antique bronze and differentiate it from a recent copy, however convincing it may be.

The contribution of scientific analysis to authenticating and dating an antique bronze

Scientific tests are becoming essential for the objective identification of a bronze when visual expertise is no longer sufficient. They provide verifiable and documentable data for professional bronze appraisal.

Microanalysis, the key to understanding the composition of bronze

Analysis of the chemical composition of an antique bronze object is often the first lever for authentication. It allows us to determine the exact nature of the metallic elements present in the alloy: copper, tin, lead, zinc or even traces of arsenic. However, the content of these elements varies significantly according to period, region and casting technique.

For example, the detection of arsenic in significant proportions may indicate arsenic copper, used in antiquity before the widespread use of bronze. This historical variant is therefore a valuable marker for dating and attributing an object to a given era. Conversely, high levels of zinc may indicate brass, and aluminum a modern bronze.

Thanks to microanalysis coupled with EDX spectrometry, it is possible to identify the elemental composition of a sculpture. This data can be used to differentiate an antique bronze from an industrial alloy that is too pure, proof of a standardized object.

These results can be cross-referenced with scientific databases to situate the piece in its historical and geographical context.

Microscopes and Corrosion: Understanding the Age and Authenticity of a Bronze

After analyzing the chemical composition of the bronze in question, an examination of the metal’s internal structure and its state of corrosion allows for a more in-depth assessment. These observations provide valuable clues about the manufacturing processes and the artifact’s true age. Laboratories conduct several types of analysis:

Metallographic microscopy: reading metal structure

Metallographic microscopy is a technique based on the observation of polished micro-sections revealed by chemical etching. It enables in-depth analysis of the metal's internal structure:

• Granulometry and dendrite size (indices of cooling)
  
• Traces of hammering or manual shaping
  
• Presence of phases metallurgical related to tin content
  

Microscopy scanning electron microscopy (SEM): observing corrosion

Scanning electron microscopy (SEM) provides an extremely precise view of the metal surface. It is particularly useful for studying corrosion layers:

• Visualization of stratification, crystallizationand oxidation products
  
• Identification of natural corrosion (slow, complex development)
  
• Detection of artificial corrosion (recently applied chemical patina)
  

Distinguishing the type of corrosion is essential to validate or invalidate authenticity. Modern patinas, even sophisticated ones, often leave traces that can be detected by SEM, unlike ancient alterations caused by burial or prolonged exposure.

Analysis of the degree and origin of corrosion

A corrosion test, combined with the SEM, is used to evaluate :

• L’thickness of corrosion layers
  
• Their chemical composition
  
• Their environmental origin (damp soil, marine atmosphere, indoor storage…)
  

These elements provide clues as to the actual age of the bronze and the conditions under which it was preserved or buried. Heterogeneous, deep, natural corrosion is often the hallmark of an old piece. Homogeneous, superficial or overly "perfect" corrosion, on the other hand, may indicate a modern reproduction with a chemical patina.

The combination of these techniques - EDX microanalysis, metallographic microscopy, SEM and corrosion studies - results in a complete, traceable and opposable scientific expertise. These methods provide objective proof of a bronze's composition, manufacture, age and origin.

This is a reliable methodology for securing a sales contract or valuing a work. The CIRAM laboratory, as a specialist in ancient materials, masters all these methods and supports art market professionals with rigorous and usable reports in these contexts.

Laboratory analysis of antique bronzes: a decisive step for art market professionals

Selecting and carrying out analyses is only the first step in the authentication process. Interpretation of the results is essential to enhance the value of antique bronzes and to integrate them into an overall appraisal or sales process. It is here that specialized laboratories bring their full value to art market professionals.

Why have your bronze objets d'art analyzed by a laboratory like CIRAM?

The intervention of a laboratory specialized in art and recognized as CIRAM is essential for authenticating an antique bronze. Its action offers a double guarantee: scientific rigor and credibility on the art market. The analysis reports produced will include all the necessary techniques implemented: EDX microanalysis, metallographic microscopy, study of the degree and origin of corrosion, and even X-ray radiography if the object allows.

CIRAM also masters the detection of historical alloy variants, such as arsenical coppers or tin-rich bronzes, and can identify metallurgical phases useful for dating and situating objects in their era.

The laboratory works on a regular basis with legal experts, auctioneers, insurers and heritage institutions, enabling analyses to be calibrated according to the real need: purchase, sale, restoration, legal appraisal or insurance.

Integrate scientific results into a professional approach

A scientific analysis of a bronze work of art is only of value if it can be understood, used and shared with other stakeholders. Expert laboratories present the results in a clear report, with photographs, protocols, interpretation and conclusions. This helps to secure an acquisition, justify a sale, or structure a restoration file in compliance with museum standards.

In some cases, metallurgical analysis can also be used to date the object's manufacture, notably by comparing the results with major historical and archaeological databases.

Finally, scientific analysis plays a dissuasive role in the fight against counterfeiting, by defining documented traceability, which can be integrated into a certificate of authenticity or an insurance inventory. For a professional, integrating this approach means using science as a lever of trust and added value.

Recognizing an authentic antique bronze can no longer be based simply on a specialist's visual appraisal, however serious this may be. Scientific analyses such as microanalysis, EDX, metallographic microscopy and other corrosion studies provide tangible, dateable proof in response to buyers' uncertainties. The results of these analyses, and their presentation in authentication files, secure transactions, enhance the value of works and provide professionals with essential traceability.

As a leading laboratory in scientific analysis and dating, CIRAM supports professionals in the art market with proven methods, including dating techniques (carbon-14, TL/OSL), imaging techniques (X-ray radiography, infrared imaging, CT scans, UV fluorescence), and characterization techniques (metallography, PIXE, chromatographic analysis)…

Would you like to authenticate a bronze, verify its composition, or determine its age? Request a customized analysis by contacting us via our contact form!

Olivier Bobin

Olivier holds a master’s degree in chemistry (1996) and a Ph.D. in Archaeomaterials Physics (2001) from the University of Bordeaux. In 2005, he co-founded the CIRAM laboratory with Richard Chéret, and today serves as its co-director and scientific director.

Studying a work of art may require information about its materials, its condition, or its history. But how can this information be obtained without risking damage to a fragile or valuable object?

Non-destructive analyses allow for the examination of certain characteristics of a work without removing material. They are of particular interest for paintings, sculptures, and heritage objects whose preservation is a priority. The choice of method, however, depends on the nature of the object, the questions asked, and the information sought. What are the possibilities offered by non-destructive analyses, and what are their limitations?

Why opt for non-destructive testing?

Preserve the integrity of the works

Artworks and heritage objects can be fragile, altered by time, or particularly sensitive to handling. Taking a fragment of paint, wood, or textile can therefore present constraints, especially when the object is unique or its state of conservation is concerning. Non-destructive analysis thus makes it possible to obtain certain information without taking a sample. It therefore constitutes a preferred approach when the characteristics of the work and the scientific question can be studied by this type of method.

This approach helps to limit interventions on the object, while providing useful elements for its study and conservation.

Obtain useful information for study and conservation

Non-destructive analyses can help characterize certain material properties, observe the structure of a work, or detect alterations. Depending on the method used, they can notably contribute to documenting the conservation status of a painting or object, observing certain structures invisible to the naked eye, or detecting modifications and restorations.

This information helps to better document the artwork and guide further investigations before potential conservation-restoration work. It is part of a broader approach to the scientific analysis of a painting, which combines different methods to study the materials, structure, and material history of the artwork.

What are the limitations of non-destructive testing?

A non-destructive method does not necessarily allow for the identification of all materials or a complete characterization of the object. The accessible information depends on the technique used, the nature of the materials, their condition, and the examination conditions.

For example, scientific imaging can reveal a structure or anomaly without precisely determining its chemical composition. Conversely, the chemical analysis of the materials in a painting aims to identify pigments, binders, varnishes, and other components of the paint layer, depending on the methods used and any sampling constraints. It is also necessary to distinguish between observing an index and demonstrating a hypothesis. The highlighting of an anomaly is not sufficient, in itself, to conclude restoration, falsification, or historical inconsistency.

When non-destructive methods do not sufficiently answer the question posed, targeted sampling or complementary analysis may be considered. This decision must take into account the scientific interest of the investigation, the condition of the object, and conservation constraints.

How to choose the appropriate method for a work of art?

The choice of an analysis method depends primarily on the objective of the study. It is not a matter of systematically mobilizing the largest number of techniques, but of selecting those that can provide the most relevant information. Several criteria must be taken into account:

• The nature of the object: a painting on canvas, a wooden panel, a sculpture, and a composite object do not present the same characteristics.
• The scientific question: observing the surface state, studying an internal structure, or characterizing a material requires different approaches.
• The state of conservation: the fragility of the work and the risks associated with its handling may limit examination possibilities.
• Intervention conditions: the dimensions of the object, its accessibility, and its storage location can influence the choice of materials and methods.
• The limits of each technique: the expected results must be compatible with the actual capabilities of the chosen method.

When several questions arise, different techniques can be combined. Cross-referencing results allows for the completion of observations and avoids drawing conclusions from a single clue. The choice of an imaging technique depends, in particular, on the information sought and the depth of observation required. To better understand the differences between optical imaging and radiography, it is useful to compare their operating principles, capabilities, and limitations.

When is further analysis necessary?

A non-destructive analysis can be a first step in the study of a work. It can sometimes clarify a hypothesis, identify an area of particular interest, or guide the choice of further investigations. Certain techniques, such as radiography, allow for example to examine the internal structure of a painting and provide complementary information on its material history. Discover in more detail what radiography reveals about the history of a painting.

However, some questions require information that cannot be obtained by non-destructive methods alone. This is particularly the case when the precise identification of a compound requires specific analysis or when the dating of an organic material is necessary. Carbon-14 dating, for example, involves organic material suitable for sampling and analysis. It should therefore not be presented as a systematically non-destructive method.

Conclusion

Non-destructive analyses play an important role in the study of works of art, as they provide scientific information while limiting interventions on the objects. An appropriate approach relies on the reasoned choice of techniques, consideration of their limitations, and interpretation of the results within their historical and material context.

Jean-Baptiste Forget

Head of Fine Art at CIRAM

X-ray analysis of paintings allows us to examine a work’s internal structure without damaging it. Using X-rays, this technique reveals past restorations, retouching, cracks, the construction of the support, and other elements invisible to the naked eye. Today, this imaging technique is an indispensable tool for the study, conservation, and authentication of works of art. Used in conjunction with other scientific analysis methods, it provides additional information that enhances our understanding of a painting’s material history. X-ray analysis is an integral part of a more comprehensive approach tothe scientific analysis of artworks.

In this article, we discuss how it works, what it can reveal, and in what situations it is used.

How does X-ray analysis of a painting work?

X-ray examination is an imaging technique that uses X-rays to examine the interior of a painting without having to take it apart or remove any samples.

The X-ray beam will pass through the paint and its substrate and be captured on a digital plate. Each material present—such as pigments, wood, canvas, and nails—absorbs the rays differently, producing a high-contrast image of the internal structure.

X-rays are used, in particular, to:

• reveal a old restorations hidden under repaints
  
• identify cracks , repairs, deformations of the substrate, or other structural damage
  
• view the revisions (changes made by the artist during the creative process)
  
• revealhidden elements such as a signature, a drawing, or iconographic elements

This information is particularly useful before a restoration, appraisal, or purchase.

X-ray analysis is a non-destructive method. The X-rays used do not alter the pigments or the support and allow a work of art to be examined without compromising its preservation.

To learn more, consult our article dedicated to non-destructive analyses of works of art.

Why supplement X-rays with other tests?

Radiography applied to paintings and canvases is distinguished from other scientific imaging techniques by its ability to penetrate all layers of the object, from the varnish to the support. Unlike infrared imaging methods, which primarily target underlying drawings, or ultraviolet, which is limited to the pictorial surface, radiography offers a comprehensive, in-depth view of the artwork.

However, there are certain limitations: analysis can be complex when dealing with mixed materials (canvas on a metal frame, modern reinforcements, wooden parquet), requiring the use of complementary methods such as computed tomography (CT scan).

This complementarity is at the heart of the scientific approach of specialized laboratories like CIRAM. Radiography is thus associated with other imaging techniques, with carbon-14 dating and chemical analyses to produce a complete and reliable diagnosis.

Why X-ray a painting?

X-ray imaging is not limited to producing a simple technical image: it serves as a strategic tool for making informed decisions, whether regarding authentication, dating, restoration, or the revelation of a work of great value.

Authenticating and dating paintings: material evidence before a transaction

For gallery owners, experts, and art collectors, the question of a painting’s authenticity is crucial before any purchase. X-ray analysis of paintings thus provides objective physical evidence that either supports or refutes an attribution.

X-rays of the paintings can be used to :

• detect changes substantial incompatibilities with the presumed period of creation: addition of modern supports, industrial retouching, anachronistic materials
  
• compare the internal structure with referenced works from the same studio
  
• check the consistency of assembly components (dowels, nails, covering)
  
• complete a dating of a painting by comparing the results with those obtained by carbon 14 or chemical analysis of materials

In practice, radiography applied to paintings clearly answers the question: how can a work of art be scientifically authenticated before being sold? It is the method of analysis that provides material proof. This analysis is indispensable for any appraisal report on serious paintings on the international market.

Restoration and conservation: concrete examples and benefits

X-rays of paintings reveal the complete stratigraphy: preparatory layers, repentirs, old restorations in the context of a restoration operation. This technical information makes it possible to adapt protocols and avoid successive treatments that would compromise the integrity of the work.

It also identifies:

• structural cracks invisible to the naked eye
  
• old consolidations likely to deteriorate
  
• heterogeneous materials (combination of wood and metal) requiring differentiated conservation

For these reasons, radiography applied to paintings provides a concrete answer to another crucial question asked by art professionals: what results can be expected for the conservation of paintings? By X-raying your work, you can obtain a detailed map of any deterioration, which is essential for drawing up an estimate, planning interventions and documenting prior condition.

Last but not least, this imaging method is a genuine scientific documentation tool for enhancing the value of the work: incorporating radiographic images and observations into the technical file enhances traceability and credibility with institutions, collectors and insurers.

Integrating results into documentation and the art market

After X-raying the painting, the laboratory provides an illustrated and commented file including :

• visit radiographic clichés detailed
  
• visit observations on the internal structure, previous restorations and any hidden signatures
  
• a synthesis of the technical limitations and recommendations for potential additions (CT scan or UV imaging)

These elements provide undeniable added value when it comes to securing a transaction or acquisition, planning a restoration, and enhancing the traceability and visibility of the artwork in the art market.

X-ray analysis is now one of the most useful imaging techniques for studying a painting without damaging it. By revealing the internal structure of the artwork, it provides valuable information about its creation, state of preservation, and history. Combined with carbon-14 dating, chemical analyses of materials, and other scientific imaging techniques, it is an essential tool for the study, conservation, and authentication of works of art.

Richard Cheret

Richard holds a master’s degree in chemistry (1999) and a master’s degree in the physics of archaeomaterials (2000) from the University of Bordeaux. In 2005, he co-founded the CIRAM laboratory with Olivier Bobin, and today serves as its co-manager and sales director.

As the science of wood applied to art, xylology plays a crucial role today in the authentication, dating, and conservation of wooden artworks. It involves identifying wood species, analyzing traces of craftsmanship, and can be combined with non-destructive imaging or carbon-14 dating. These scientific approaches help verify the origin, value, and longevity of works of art and antique furniture.

For art professionals, whether they are gallerists, experts, or even collectors, it is essential to rely on a specialized art laboratory like CIRAM to guarantee reliable, documented expertise adapted to market demands or for valuation purposes.

In this article, we explore what xylology is, how it can be applied to the study of wooden objects, and what role laboratories play in helping us better understand the origins of these works of art.

Understanding xylology: a science at the service of artistic heritage

Long confined to the life sciences or environmental archaeology, xylology has established itself as a strategic discipline for art professionals faced with challenges such as the authentication, conservation and traceability of works in wood.

Definition and origin of xylology

What is xylology? It is a scientific discipline dedicated to the study of wood, through the analysis of its anatomical structure, its physical and chemical properties, its botanical origin, and its evolution over time. This field of analysis is part of a multidisciplinary field, intersecting botanical xylology, dendrochronology, archaeo-dendrometry, and sometimes even anthracology.

However, xylology is not limited to a descriptive analysis within the art market. It becomes a decisive tool for the authentication of wooden art objects, for dating antique furniture, or for identifying the wood species used in a sculpture. It thus directly meets the expectations of gallery owners, restorers, experts, or art collectors wishing to secure the provenance of a work.

Why xylology is essential to the art market

In a context where forgeries are circulating on a massive scale and regulations are intensifying, xylology applied to the art market can meet several critical needs:

• Identify wood species and check their geographical and temporal coherence with the work studied (choice of wood species for objets d'art).
• Detect any modern additions or hidden restorations by analyzing tool marks on old wood or using non-destructive methods (radiography, tomography).
• Ensuring the traceability and provenance of a work of art, now a central criterion in any transaction or insurance procedure.
• Integrate wood analysis into a preventive conservation approach, particularly for ethnographic wooden objects and archaeological furniture.

That's why xylology isn't just about the science of wood. It is part of a global approach to heritage enhancement, combining scientific rigor, technical expertise and economic stakes.

Applying wood science to wooden objects

Xylology makes it possible to objectively analyze works of art in wood, whether for appraisal, dating or heritage conservation purposes.

Scientific methods for xylological analysis

As we have seen, xylological analysis can be combined with a range of complementary techniques, selected based on the nature of the object, its state of preservation, and the objectives of the study (authentication, dating, identification, conservation). Laboratories that conduct xylological studies, such as CIRAM, therefore employ several approaches:

• Microscopic observation: this allows for the recognition of wood structures (fibers, rays, vessels) in order to precisely identify the species. This step is crucial for identifying wood species, which determines all historical recontextualization. In practice, species identification relies on the anatomical observation of wood according to three planes of analysis: transverse, tangential, and radial. Samples are examined under a microscope to identify cellular characteristics such as vessels, pore structure, the presence of tyloses or parenchyma, as well as the shape and distribution of wood rays. These observations are then compared to wood reference collections, called xylotheques, allowing for the precise identification of the tree's family, genus, and sometimes species.
• Physico-chemical analyses: they reveal the chemical properties of the wood (treatment residues, presence of glues or pigments) and detect alterations, consolidations, or undocumented subsequent interventions.
• Dating archaeological wood: radiocarbon dating proves particularly reliable for chronologically situating a work, even when it is fragmented. It can be supplemented by dendrochronology, when the growth ring series is legible and a regional reference exists. Xylology also constitutes an essential tool for certain dating approaches: it is notably used in our "augmented radiocarbon" dating technique, by allowing estimation of the tree's growth rate and thus reducing the radiocarbon dating intervals for tribal art objects to a few decades.
• Non-destructive techniques: they include various analysis methods such as radiography, tomography, or scientific imaging and allow intervention on valuable objects without sampling. These technologies facilitate the conservation and restoration of objects by documenting internal alterations invisible to the naked eye.

Concrete applications in the art market

The methods described above have direct applications in the analysis of archaeological furniture, ethnographic wooden objects and ancient sculptures. Xylology for art thus makes it possible to :

• Authenticate a work by revealing a wood inconsistent with the supposed period or geographical area.
• Determine the manufacturing techniques, through the analysis of shaping or assembly traces.
• Contribute to historical reconstruction, in connection with the evolution of the woody environment or the influence of climate on archaeological wood.

For art market professionals, these technical data provide a verifiable scientific basis for any appraisal, and reinforce the work's documentary and commercial value.

Xylology, the art market and the role of specialized laboratories like CIRAM

Even though compliance, transparency and valuation requirements are becoming increasingly stringent, xylology remains a strategic asset for art market professionals. Laboratories carrying out xylological analyses bring real added value to art professionals.

Economic, regulatory and commercial issues

Today's art market imposes ever stricter rules on the traceability and provenance of works of art. In this respect, xylological analysis provides the concrete proof expected by experts, insurers, auction houses and control institutions.

In particular, it allows you to :

• Document the origin of the wood by identifying the wood species and their compatibility with the presumed geography.
• Meet regulatory compliance requirements, particularly for the import/export of protected or high heritage value wooden objects.
• Avoid legal or commercial disputes thanks to reliable and verifiable wood expertise, objectified by complementary methods such as physico-chemical wood analysis, radiocarbon dating of wood, etc.).

As a result, methods for authenticating wooden objects—backed by scientific evidence—significantly enhance a work’s commercial value, while ensuring that collectors acquire pieces that are ethically and historically validated.

CIRAM's key role in the analysis of wooden objects

In France, CIRAM is one of the few laboratories to offer a multidisciplinary and comprehensive approach to the analysis of wooden objects, combining scientific rigor with in-depth market knowledge.

The services provided by the laboratory teams include :

• L’non-destructive wood analysisvia radiography or tomography to preserve the integrity of works of art.
• A combination ofxylology, dendrochronology, scientific wood imagingand carbon-14analysis for reliable dating and authentication.
• Personalized support, tailored to the specific needs of gallery owners, restaurateurs, and collectors, delivered within timeframes that align with market demands.

The criteria for the reliability of wood science analysis at CIRAM are based on certified analytical chains, transparent documentation, and interpretations contextualized by specialists in archaeological furniture and wooden artifacts.

Finally, for professionals looking for quality control or certification of biobased products, xylological analysis is a natural part of a responsible approach to value enhancement, at the crossroads of science, art and ethics.

To conclude this article, let us note that xylology has established itself as an indispensable science for authentication, complementing the dating and conservation of wooden artifacts. By employing rigorous methods such as species identification, physicochemical analysis, non-destructive imaging, carbon-14 dating, and other applicable techniques, xylological analysis meets the needs of professionals seeking reliable, traceable, and valuable authentication of their works of art.

As a global leader and recognized specialist in scientific analysis for the art market, CIRAM offers comprehensive expertise in xylology, wood archaeology, and radiocarbon dating, tailored to the needs of gallery owners, collectors, experts, and cultural heritage institutions.

Would you like to verify the authenticity of a work of art or confirm its provenance?
Request apersonalized assessmentfrom the CIRAM team.

Joey Montagut

Archaeobotanist, Joey graduated from the École Supérieure du Bois (Nantes – 2002). He specialized in the identification of archaeological and contemporary woods (Xylology) and charcoals (Anthracology).