Influence of acoustic effects on museum exhibits.
Mutual investigations of the State Hermitage, of the academician Igor Grabar All-Russian art scientific-restoration center and of the "Electropribor" enterprise

17 July 2008, the State Hermitage press-cutting service has presented results in investigations concerning to influence of acoustic effects on museum exhibits.

The Palace square permanently becomes a place for some different popular urban measures (various concerts, sportive programs, outdoor festivities etc.). At their realization, high-power acoustic systems are used, that produces vibration of glasses in museum windows and show-cases, affecting sound pressure to art works. Together with it, the museum main task is keeping both historical edifices of museum complex and its exhibits. It should be noted that museum keeping requirements even limit air velocity in premises, and the Hermitage brings significant expenses for improvement of ventilation and air conditioning systems.

Sound impact is especially seriously reflected on painterly canvases. Physical-mechanical oscillations of canvases together with combining effect of oxygen, light and humidity fluctuations contribute to accelerated penetration of water steams with contaminants into material structure and to unpredictable acceleration of processes of ageing pictures. Asymmetrical humidity distribution at action of acoustic high frequency field promotional to drying might cause formation or multiple shelling augmentation, exfoliation and talus of paint layers.

In 2007 the State Hermitage, the academician Igor Grabar All-Russian art scientific-restoration center and the "Electropribor" enterprise have begun to fulfill investigations concerning to influence of acoustic effects on museum exhibits. Pictures of auxiliary All-Russian art scientific-restoration center fund have been used as patterns tested. These pictures have been delivered into the "Electropribor" enterprise and back around into All-Russian art scientific-restoration center in special containers in order to avoid of supplemental vibrations at transportation.

Before the beginning of investigations, one has defined maximal vibration levels on painting surface in the Hermitage halls and also sound pressure levels in these premises on July 28, 2007 during performance of the "Rolling Stones" group. Measures have pointed that average sound level has made 88 dB.

At middle concert continuity making two hours and average quantity of concerts making ten in a year, estimated value of acoustic affecting exhibits will make 200 hours for ten years.

Further, tests have been fulfilled, in course of which sound pressure levels have been measured in points located near surface of patterns. After each affecting assigned sound pressure and sound pressure with maximal levels in range of frequencies for 50 and 100 hours, one has registered levels of shift due to vibration on painting in point defined upon the "Electropribor" method and octave sound pressure levels in range of frequencies 31.5-8000 Hz, each 24 hours. The visual examinations have been also fulfilled for detecting some possible coat layer destruction of control pieces fixed.

Results in macro- and microanalysis of paint canvas state before and after acoustic affecting have pointed appearance destruction focuses of primary structure in paint layer, weakening bonds of author’s painting with priming and prime coat with canvas fibers, certain increasing dimensions of minute cracks being earlier in coat varnish and other non-significant change. On the whole, 200-hour impact of continued, repeating sound fluctuations, high sound pressure (80-82 dB) has made patterns about 35-40 years older.

Thus, even at minimal estimations, performance of ten concerts a year additionally makes a picture one year older.

The State Hermitage continues to fulfill and to make more precise investigations of acoustic affecting exhibits and also begins the program of vibration study and estimation pertaining to museum exhibits and edifices.