Analytical techniques
The use of instrumental analytical techniques using science and technology to determine the chemical identity (of a chemical element or compound) of materials used in the construction of cultural heritage projects started in the early 20th century. Around 1990 the scientific community started to show increased interest in the study and recording of art history related materials and manufacturing techniques.
Analytical techniques are used to help identify a work of art's construction materials and to record their proportions (amount). Here are the main analytical techniques used by the Laboratory of Physicochemical Techniques when analyzing works of art.
Analysis Results
The analytical examination of cultural heritage objects provides some basic information, such as:
The identification of inorganic materials present in an artwork, e.g. pigments, plaster, chalk, etc.
The identification of organic materials that make up a artwork, eg adhesives, oils, varnishes
Recording of maintenance materials used for the restoration of an artwork
Recording of the materials used to make changes, like over-paintings, application of new varnishes, etc.
Chronological placement of artwork
Determination of aging and decomposition of organic material
Types of analytical techniques
These are divided into two basic categories: spectroscopic and chromatographic methods of analysis, with a third category that includes several other techniques. Spectroscopic techniques are methods that measure the radiation spectrum of a substance, i.e. the intensity of radiation at a wavelength, and these in turn are divided into molecular techniques and elemental techniques.
Chromatographic analysis methods are able to classify organic compounds into components by recording the each component's unique behavior under given analytical conditions.
Form of samples required
Most analytical techniques require a micro-sample of the artwork. Samples are obtained either in the form of fragment, i.e. small particle amounts which do not affect the integrity of the work. This type of procedure is called invasive because it requires physical elements of the work in order to attain a sample. Invasive techniques are in turn divided into either destructive, where a non-reusable sample is required in order to complete analysis, and non-destructive, that requires a reusable sample.
There are also analytical techniques which are non-invasive, i.e. that offer analysis without sampling.