'Rembrandt: The Late Works': A Resource for Science Teachers

The analysis of paint materials

Scientists at the National Gallery investigate the materials used in paintings, including the coloured pigments, the binder that holds them together and the canvas or wooden panel on which the artists painted, called the support. Knowing about the materials the artist used can help researchers to understand when and where the paintings were made. It can also explain significant colour changes that can take place over time.

Blue pigment being ground with oil to make a paint
Blue pigment being ground with oil to make a paint

 

Information about materials is important in supporting the decisions made when the Gallery’s conservators carry out conservation treatments. When a painting is cleaned, for example, knowing what materials are present in the uppermost varnish layers is particularly useful.

Leonardo Da Vinci’s ‘Virgin of the Rocks’ in the conservation studio at the National Gallery, London.
Leonardo Da Vinci’s ‘Virgin of the Rocks’ in the conservation studio at the National Gallery, London.

 

Imaging techniques such as X-radiography and infrared reflectography can provide a lot of information about the structure and make-up of paintings. However, to investigate the paint and varnish in more detail, very tiny samples are taken from the painting. This is usually done with a scalpel while looking down a microscope. Sometimes these samples can be prepared as a cross-section, which shows the different paint layers.

A paint cross-section being examined under a microscope in the Scientific Department at the National Gallery, London.
A paint cross-section being examined under a microscope in the Scientific Department at the National Gallery, London.

 

Samples or cross-sections can be analysed with sophisticated instruments such as Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analysis, Gas Chromatography–Mass Spectrometry (GC-MS) or Fourier transform infrared (FTIR) spectroscopy.

Analytical equipment used by scientists working at the National Gallery, London: (from left to right) scanning electron microscope with energy dispersive X-ray analysis, gas chromatography – mass spectrometry and infrared spectroscopy.
Analytical equipment used by scientists working at the National Gallery, London: (from left to right) scanning electron microscope with energy dispersive X-ray analysis, gas chromatography – mass spectrometry and infrared spectroscopy.

 

Additional material:

See how the blue and red pigments traditionally mixed to make purple paint are analysed and identified in the National Gallery Scientific Department:

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