An oil painting has been proven to be one of Claude Monet 's - after scientists discovered the artist painted over his own signature . The 1891 painting , titled ' A Haystack in the Evening Sun ' , was largely unknown and its origin had never been verified . But a team of researchers from the University of Jyväskylä in Finland painstakingly unearthed the signature . Scroll down for video . An 1891 oil painting - titled ' A Haystack in the Evening Sun ' - has been proven to be one of Claude Monet 's despite the artist painting over his own signature . The painting has been owned by the Gösta Serlachius Fine Arts Foundation , also in Finland , for more than 50 years . It is thought to be part of a wider series by Monet with all the pieces illustrating stacks of hay in fields after the harvest season . The painting was verified after a special camera was used to examine the composition of the work . This allowed researchers to see different layers including a previous signature by Monet . It is thought to be part of a wider series by Monet ( above ) with all the pieces illustrating stacks of hay in fields after the harvest season . Ilkka Pölönen , a researcher , said the camera scans one 'line ' at a time . He told ArtDaily : 'When the camera is moved using the scanner an image of the whole picture can be obtained . ' The Fine Arts Foundation said the artwork is the first Monet painting to be held in a Finnish public collection . The other paintings from the series are held at various galleries including the Art Institute of Chicago , the National Gallery of Scotland and the J. Paul Getty Museum in California . X-ray fluorescence ( XRF ) is a non-destructive technique , which can identify the presence of certain pigments . It was first used in the 1940s and applied to paintings in the 1950s . The technique involves bombarding the artwork with x-rays so powerful that they cause atoms in the picture ’ s layers to emit ‘ florescent ’ x-rays of their own . XRF can be used to identify the colours of hidden paintings or to see earlier versions of famous pieces . By mapping the x-rays of copper , for blue and green , iron , for yellow , orange and brown , and mercury , for red , scientists can see full-colour 'maps ' of previous versions . In this case a special camera was used to examine the composition of the work . This allowed researchers to see different layers including a previous signature - verifying that the painting was by Monet .
Oil-painting titled ' A Haystack in the Evening Sun' is from 1891 . Researchers in Finland used special technique to unearth signature .