Colour measurement of acid-detector strips for the quantification of volatile organic acids in storage conditions

Abstract

Acid-detector (A-D) strips were originally developed to assess the deterioration of acetate film stock, but they can also be used more generally within enclosures to detect volatile acidic pollution. A hand-held reflectance spectrophotometer was used to record the colour of individual strips in order to make consistent and reproducible readings. Calibration was carried out using the yellow-blue axis b*(D65) value in the CIELAB1976 system to measure the colour of A-D strips suspended in enclosed containers over solutions of acetic acid in combinations with glycerol to control the relative humidity (RH). A-D strips were found to be sensitive to changes in high RH (60-90%) but affected little by changes in lower RH or temperatures in the museum display and storage range. A-D strips can be used to establish the presence of volatile acids, record the indication of acid vapour concentration, explore conditions within a container, and to find sources of volatile acidity. They respond very quickly and several can be placed around an object. They therefore show promise for measuring slowly changing conditions, such as seasonal changes and the gradual accumulation of acidity in poorly ventilated containers and spaces. A-D strips proved useful in assessing air quality in storage and display enclosures. Examples and test results are presented. Wellsealed plywood transit frames and storage cases were found to be most polluted with volatile acids. Storage rooms with air filtration systems but filled with wooden objects had significantly reduced air quality.

Crystalline Deposits in New Display Cases at the Rijksmuseum: Characterisation and Origin

“…Gaseous pollution due to outgassing of exhibition materials is often involved in the formation of deposits. Therefore, several methods have been developed to analyse common harmful gasses emitting from exhibition materials (Schieweck, Markewitz, and Salthammer 2007;Ashley-Smith, Burmester, and Eibl 2013; Lankester, and Thickett 2015; Grøntoft et al 2016;Hackney 2016;Leyva Pernia 2019). Even though the Rijksmuseum display materials had been tested for outgassing prior to application, deposits had formed soon after installation of the cases.…”

Indoor air pollution impact on cultural heritage in an urban and a rural location in Romania: the National military museum in Bucharest and the Tismana monastery in Gorj County

“…It would be beneficial to keep the rooms cool, and ventilate the rooms under good (dry, cool) outdoor conditions without producing dramatic climatic fluctuations. As organic acid attack increases significantly at higher air humidity (> ~ 60%), this would be especially important to avoid [37,[39][40][41]. To most organic objects the acidic atmospheres would be of little risk [6,14].…”

“…(1), the original statistical doseresponse equation for the GSD dosimeter does not, include formic acid [23]. Formic acid is however a stronger acid than acetic acid and is known to have degrading impacts [4,37]. In museum locations the presence of formic acid typically correlates with that of acetic acid, with a concentration of about 25% that of acetic acid, but with large variation [9,11,12].…”

Monitoring pollutant gases in museum microclimates: a relevant preventive conservation strategy

“…Nas últimas décadas, a poluição diminuiu de forma significativa em muitas áreas urbanas, em particular, os níveis de SO2 [2,27]. Adicionalmente, muitos museus começaram a implementar a utilização de sistemas que impedem ou reduzem a entrada de poluentes externos, como filtros de gases e de partículas, além de proteger as obras mais frágeis com vitrinas ou vidros [28]. Os poluentes podem ter ação nociva sobre diversos materiais, nomeadamente, promover a corrosão de metais, reagir com pigmentos e aglutinantes ou catalisar reações de degradação de polímeros [29].…”