SCIENCE IN THE SERVICE OF ART

Dating and Analysis of Art Objects

Scientific dating and analysis of art objects brings together different techniques and methods that allow for rigorous and objective authentication based on the measurement of the physical-chemical properties of materials. We will distinguish two main categories of materials: datable and non-datable.

The datable materials correspond to wood, ivory, textile, paper, parchment … which will be dated by carbon 14 (C14). Terracotta, porcelain, earthenware can also be dated by thermoluminescence (TL test). Non-datable materials such as stone, metal, glass and paint will be studied by micro-analysis. These age tests will help define the period of manufacture of the objects: ancient or modern.

The world leader in the dating and analysis of art and heritage objects, CIRAM analysis laboratories have been examining art and heritage objects for more than fifteen years with dedicated teams of doctors and engineers who are experts in their field.

Ceramics and Terracotta

Ceramic, terracotta, porcelain or earthenware art objects can be analyzed using a technique called thermoluminescence or TL testing. The thermoluminescence analysis (TL test) allows to define an approximate dating of the last firing of the material. TL tests are therefore quite appropriate for the authentication of terracotta and ceramics in general.

A thermoluminescence laboratory (TL Test)

CIRAM has its own thermoluminescence dating laboratory (TL and OSL) using the techniques and protocols of public laboratories. To date a terracotta artifact, our teams of scientists perform a thermoluminescence test (TL test) to obtain an approximate dating of the last firing of the material.

The thermoluminescence test (TL test) relies on the ability of quartz and feldspar crystals to accumulate and then release environmental radioactive energy in the form of light when heated. With this method, it is possible to estimate the age of the last firing of the object. Concretely, our scientists take a sample, subject it to chemical treatments to eliminate potential pollutants, then heat the material to 500°C and measure the amount of light emitted in the ultraviolet range. The amount of light emitted is proportional to the age of the ceramic or terracotta.

Bronze, silver, and gold

Bronze, silver, and gold are not scientifically dateable. Therefore, our researchers have developed alternative analytical techniques to measure objective indicators that can be used to make judgments about the age of metal art objects.

Depending on the metal used to make the art object, our laboratories use several methods for analysis. The antiquity test is based on several factors. The type of metal already gives answers. The presence of aluminum, phosphorus, manganese, chromium, for example, even in very small quantities, is a formal indication of modernity. The second step is to define the degree of corrosion of the metal and the origin of this corrosion.

The authentication of metals

The analysis of metals varies according to its nature. For bronze, brass or silver, it is possible to analyze the degree of corrosion to get an idea of the age. Then, the origin of the corrosion will be a preponderant element in the authentication of a bronze statue for example. The analysis of gold is a little different, because gold does not corrode or does not corrode very much, so another methodology will have to be adapted. We will analyze the composition in trace elements (elements whose concentration is lower than 0,1 %). We may also perform a surface study, in order to identify gold corrosion figures (corrosion at grain boundaries for example).

Scanning electron microscopy (SEM) allows to define both the chemical composition of the metal and its degree of corrosion. If the shape and manufacturing technique of the object (closed shape and lost wax casting) allow it, we can complete our analysis with a thermoluminescence test (TL test).

The authentication of metals is a complex science enabled by the know-how and experience of our teams who know how to couple all the techniques and methods for an accurate expertise of the art object.

The analysis of a painting

The analysis of a painting allows to date a painting according to its support and its pigments. Carbon 14 dating will be used to date the support (canvas, wood, paper…). Chemical analysis with a scanning electron microscope (SEM) will allow us to identify the nature of the pigments and fillers used. Scientific imaging (grazing light, Ultraviolet – UV, Infrared – IR and X-ray radiography – RX) allows to see the invisible. That is, these techniques will reveal preparatory drawings, repentirs, restoration areas, hidden signatures or inscriptions.

The CIRAM laboratories are able to analyze all types of paintings, from primitive art to contemporary paintings through the Italian Renaissance thanks to methods adapted to your problems.

The dating of a painting

Scientific analysis of a painting makes it possible to date the support, obtain chronological information on the pigments, define the pictorial techniques and observe the degree of conservation of the work.

For the analysis of a painting, CIRAM has several laboratories with specialists for:

• Carbon 14 dating (also called C14) on the support (canvas, wood, parchment paper).
• Chemical analysis of pigments to obtain chronological information.
• Scientific imaging, including grazing light, ultraviolet (UV) light, infrared (IR) reflectography, and X-ray (RX) radiography.

As the world leader in the dating and analysis of art objects, CIRAM has state-of-the-art laboratories and the best scientists for the most accurate expertise possible.

Analyzing and Authenticating Stone Sculptures

Chemical analysis of stone allows for authentication and pronouncement on the age of a stone statue or sculpture. The methodology involves three steps: the first is to identify the nature of the rock, the second is to determine the degree and origin of the alteration of the rock, and the last is to analyze the superficial deposits and tool marks, in order to verify that they are natural and correspond to traditional techniques. From the perspective of conservation-restoration, the scientific analysis of the stone also allows us to determine the cause of deterioration (humidity, environment, etc.) in order to remedy it.

The dating of the stone

For the authentication and analysis of a stone sculpture or statue, it is important to examine the constituent material of the object, the degree and nature of alteration, and, to identify the nature of the superficial deposits and tool traces. These analyses are performed by scanning electron microscopy (SEM). This method determines the age or modernity of the sculpture.

CIRAM, the world leader in art object dating and analysis

To deliver a complete and accurate analysis, our expertise relies on specialized laboratories depending on the techniques. Our scientists couple the different techniques to meet your needs. Our expertise is recognized worldwide with world-class clients such as the Louvre Museum in Paris.