Discovering the defects in paintings using non-destructive testing (NDT) techniques and passing through measurements of deformation

S. Sfarra, C. Ibarra-Castanedo, D. Ambrosini, D. Paoletti, A. Bendada, X. Maldague

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


The present study is focused on two topics. The former is a mathematical model useful to understand the deformation of paintings, which uses straining devices, adjustable and micrometrically controlled through a pin implanted in a hollow cylinder. Strains were analyzed by holographic interferometry (HI) technique using an appropriate frame. The latter concerns the need to improve the conservator's knowledge about the defect's detection and defect's propagation in acrylic painting characterized by underdrawings and pentimenti. To accomplish this task, a sample was manufactured to clarify the several uncertainties inherent the influence of external factors on their conservation. Subsurface anomalies were also retrieved by near-infrared reflectography and transmittography techniques, using LED lamps and several narrow-band filters mounted on a CMOS camera, working at different wavelengths and in combination with UV imaging. In addition, a sponge glued on the rear side of the canvas was impregnated with a precise amount of water by means of a syringe to verify the stretcher effect by digital speckle photography (DSP) technique (using MatPIV). The same effect also affects the sharp transition of the canvas at the stretcher's edge. In this case, the direct mechanical contact between stretcher and canvas was investigated by HI technique. Finally, advanced algorithms were successfully applied to the square pulse thermography data to detect three Mylar $$^{\textregistered }$$ ® inserts simulating different types of defects. These fabricated defects were also identified by optical techniques: DSP and laser speckle imaging.

Original languageEnglish
Pages (from-to)358-383
Number of pages26
JournalJournal of Nondestructive Evaluation
Issue number3
Publication statusPublished - 2014
Externally publishedYes


  • Defects
  • Deformations
  • Digital speckle photography
  • Holographic interferometry
  • Paintings
  • Square pulse thermography

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering

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