Continuous Monitoring of Damage Using Piezoelectric Quartz Crystal Based Dosimeters

M. Odlyha ¹, B.Ormsby², K.Pratt ³, J.M.Slater¹, M.Ryhl-Svendsen⁴, T.Padfield⁴, V.Smith⁵, L.Bullock⁵ , F de Santis⁶ & J.J.Boon⁷

Birkbeck College, University of London, United Kingdom ¹
Tate Conservation Department, United Kingdom ²
University College London, United Kingdom ³
National Museum of Denmark ⁴
El Alcazar, Spain ⁵
Istituto Inquinamento Atmosferico, CNR, Italy ⁶
FOM Institute for Atomic and Molecular Physics, The Netherlands ⁷

This paper describes the preparation, laboratory and site evaluation of arrays of organic coated piezoelectric quartz crystals. The work is part of the European Commission supported project, Microclimate Indoor Monitoring in Cultural Heritage Preservation, MIMIC, contract no. EVKV-CT-2000-00040. The coating which has been used consists of (1) egg tempera and (2) resin mastic varnish. 10MHz piezoelectric quartz crystals were coated using an air-brush and after a period of curing the crystals were exposed to controlled environmental conditions (laboratory test rig) and uncontrolled environmental conditions in a number of museums and historic castles in Northern and Southern European locations. In the laboratory crystal arrays were exposed to selected values of RH and then selected values of NO2 at 50%RH to test the concentration dependence of the coatings. Cumulative damage was measured following a number of exposures. Light ageing was also performed of the crystal arrays. At the sites exposure of the crystal arrays was performed initially as passive samplers and values were read before and after exposure, and more recently on a continuous basis. The sites where the crystal arrays were exposed were monitored for the following: RH,T, light, and pollutants (NOx,NO2,SO2,O3,HNO2 and HNO3). In addition to the crystal dosimeters, egg tempera and resin mastic coated metal or Melinex strips were also exposed. Egg tempera coatings had been used in a previous project and experience obtained in their behaviour on site exposure (1) (2). Coatings were analysed by infrared spectroscopy (FTIR), dynamic mechanical thermal analysis, and mass spectrometry to determine the nature of the chemical change that occurred on exposure.

References:

1. O.F van den Brink, G.B.Eijkel and J.J.Boon, Dosimetry of paintings: determination of the degree of change of mseum-exposed test paintings by mass spectrometry, Thermochimica Acta 365 (2000) 1-25
   
   
2. M.Odlyha, N.S.Cohen and G.M.Foster "Dosimetry of paintings : determination of the degree of chemical change in museum exposed test paintings (smalt tempera) by thermal analysis" Thermochimica Acta 365 (2000)35-44.

Part 2: Slides from presentation

Author to whom correspondence may be addressed:

Marianne Odlyha
Birkbeck College
Gordon House
29 Gordon Square
WC1H OPP London
United Kingdom

E-mail: m.odlyha@bbk.ac.uk