Exposing the fakers, forgers
and fraudsters
London Regional Group: The detection of fraud in paintings, Belgrave
Square, London
With paintings such as Rubens’ Massacre of the Innocents
going under the hammer for nearly GB£50m a couple of years
ago, there is every incentive to fake a masterpiece.
But how to spot the forgery from the genuine article requires
a complex range of skills, ranging from relatively simple
detective work to some highly developed chemical analysis.
SCI’s London Regional Group was treated to a fascinating talk
on the subject by Dr Nicholas Eastaugh, a scientific consultant
specialising in art, on 18 January 2005.
In his talk, ‘The detection of fraud in paintings’,
Dr Eastaugh explained that a painting is composed of a support
(such as a canvas or wooden board), a layer of preparation,
a preparatory drawing, a series of paint layers, and a varnish.
One or more of these components can be tampered with, but
there are some definite giveaways. A painting based on an
old wooden board, for example, does not necessarily indicate
authenticity; someone may have just painted on an old board.
Pigments are ‘information rich’ — there are
often many of them in a painting, and each has many variations,
including the raw material source or method of manufacture.
Dr Eastaugh focused on their analysis for most of his talk.
Ultramarine, made from lapis lazuli, is used as a dating
pigment, because natural ultramarine was no longer used after
a certain date. The pigment was prohibitively expensive in
Renaissance times, due to its long journey from Afghanistan,
and so was used very sparingly, often just for the Madonna’s
robe. Renaissance artists even had a special provision for
purchasing ultramarine written into their contracts, along
with the gold leaf.
All that changed in the 1820s when a competition was launched
in France to find an artificial substitute, so any supposedly
Renaissance painting which contains the substitute is a fake.
A forger who got wise to this, and used authentic ultramarine
to fake an old painting, might be surprised to find himself
caught out after all. Modern lapis is sourced in Russia and
South America.
 Some
substances lend themselves well to this kind of geological
sourcing. It is possible to characterise the isotopes and
trace elements of lead in lead-based pigments, the sulphur
in ultramarine, or examine the general composition of iron-based
earth pigments.
Dr Eastaugh discussed some of the methods used for obtaining
pigment samples. If a cross-section is needed to look at paint
layers, a sample of pigment needs to be physically removed
from a painting. Where possible, this is taken from the very
edge of the painting, under the frame. Fortunately there is
quite a collection of samples previously taken from paintings,
including many in London’s National Gallery, so these
samples can be reused as new techniques develop.
Current methods of analysis include polarised light microscopy,
elemental analysis by X-ray spectrometry and structural characterisation
with X-ray diffraction. Increasing use is being made of newer
techniques such as Raman microscopy, which uses a laser beam
to interact with the molecules in the material and scatter
some of the light.
The success of analysing pigments depends on information
about the materials being both up to date and widely available.
Together with some colleagues, Dr Eastaugh has set up the
Pigmentation Project to do just that. To date the project
has published a two-volume Pigment compendium and has set
up a database, Lazurite, which features sample analysis, images
and information on sampling sites. The project can be viewed
online here at www.pigmentum.org.
by Joanna Pegum
Web Editor
|
