Proceedings e report - Firenze University Press

EFFECT OF THERMAL TREATMENT ON STRUCTURAL DEFECTS OF MODEL PANEL PAINTINGS
All the defects that have been suggested by NG as signature defects have been detected both on the
untreated and the thermally treated samples. Yet only a few defects attributed to thermal ageing can be
related to a specific thermal protocol or a particular type of sample. For example, a signature defect
has appeared on sample 2.2 after thermal treatment, but this was not detected on sample 6.1 that has
undergone the same thermal procedure. Concerning the sample 5.1, the fringe pattern looks more or
less similar before and after treatment. For samples 3.2 and 6.1, the surface texture looks altered after
treatment. Concerning the sample 1.2 no conclusions can be extracted as the test conditions were
different before and after thermal treatment.
(a) (b) (c)
Fig. 5. (a) Visible image of the sample Group 5 N o 1; (b) Untreated sample – 1 min 30 sec after front heating; (c)
Thermally treated sample – 1 min 30 sec after front heating.
(a) (b) (c)
Fig. 6. (a) Visible image of the sample Group 6 N o 1; (b) Untreated sample – 1 min after back/front heating; (c)
Thermally treated sample – 1 min after back/front heating.
4. Conclusions
The thermal treatment of model panel paintings performed at the framework of MultiEncode European
Project successfully served the aims of the holographic experiments referring to repeatability.
Nevertheless, the several thermal programs that have been investigated by NG may be considered only
as preliminary results of the integral study of artificial ageing. Such protocols should be based on a
complete series of experiments involving humidity, UV-radiation and their combinations.
Additionally, it has to be examined whether the structural diagnosis, the chemical analysis or the
measurement of mechanical properties is the optimum method for studying the effects of such
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