Fresco thermographic inspection by convective heating technique

Various Thermal/Infrared Non Destructive Testing techniques are gaining interest expanding the number of applications. The non-contact nature and the increased reliability of findings make this method particularly interesting for the works of art NDE. This work is devoted to the frescoes inspection for the sizing of detached plaster areas. Air filled voids in between the coloured plaster and the supporting wall are well identified due to the increased thermal resistance. Defects are evaluated from the evolution in time of the surface temperature detected by an IR camera in transient thermal regime. The inspection of large surfaces was recently and successfully applied by means of a lateral heating. An advantage of this procedure is the reduced inspection time. This aspect is extremely important when the thermal diffusivity of the material is low, so that a long time is needed for the thermal signal appearance.