Uncovering art forgeries through radiocarbon dating

Uncovering art forgeries through radiocarbon dating

Art forgeries have existed since antiquity, but with the recent rapidly expanding commercialization of art, the approach to art authentication has demanded increasingly sophisticated detection schemes. The detection of forgeries in artworks requires increasingly sophisticated techniques. So far, the most conclusive criterion in the field of counterfeit detection is the scientific proof of material anachronisms. The establishment of the earliest possible date of realization of a painting, called the terminus post quem, is based on the comparison of materials present in an artwork with information on their earliest date of discovery or production. This approach provides relative age information only and thus may fail in proving a forgery.

Radiocarbon (14C) dating is an attractive alternative, as it delivers absolute ages with a definite time frame for the materials used.  The method, however, is invasive and in its early days required sampling tens of grams of material. With the advent of accelerator mass spectrometry (AMS) and further development of gas ion sources (GIS), a reduction of sample size down to microgram amounts of carbon became possible, opening the possibility to date individual paint layers in artworks.

To determine whether radiocarbon (14C) dating is a reliable method to detect post-1950 art forgeries, researchers dated a known forgery created in 1985 by extracting microsamples from both the pictorial layer and canvas.

The authors report that 14C analysis of the canvas was consistent with an 1866 attribution, which is the signed date on the canvas. Preliminary analysis of the paint revealed the presence of inorganic pigments in a mixed binding medium coated with a layer of varnish.

The paint sample cleaned from the varnish yielded as much as 20 µg carbon, in which the authors detected an excess of 14C, which is characteristic of the nuclear testing period during the 20th century. Specifically, the oil used to bind the pigments was harvested from seeds between either 1958–1961 or 1983–1989.

The results contradict the dating of the support material and suggest that the forger recycled an older canvas to increase the counterfeit’s credibility. According to the authors, radiocarbon dating of micropaint samples could help detect modern forgeries if suitable sampling locations are identified.