A Revised Method to Calculate Desalination Rates and Improve Data Resolution

Chris White, Marilen Pool and Norine Carroll - 2010

ABSTRACT: Conservators at the Arizona State Museum Conservation Lab treat ceramics to remove soluble salts and to prevent ongoing salt damage in objects. The most appropriate method for removing soluble salts generally depends on dissolution and diffusion of the salts into a wash bath of distilled or deionized water. This article, to be published in the Journal of the American Institute for Conservation (JAIC) describes the desalination measurement process developed at the Arizona State Museum Conservation Lab. The full text may be found in the Spring/Summer 2010 JAIC volume and is available through the American Institute for Conservation of Historic and Artistic Works.

The process is a modification of a similar system to measure the diffusion rate of salts in desalination baths. Measurement of salt diffusion into wash water is routinely evaluated as a proxy for progress in desalination treatments. The revised technique allows for increased data resolution, and accommodates variable increments of time between measurements. The revision potentially reduces the possibility of error introduced by the similar, earlier technique.

This work builds on previous conservation research focused on normalized conductivity in which the measurement of object mass and water volume provides data that is comparable between treatments. The research was undertaken at the Arizona State Museum as part of conservation treatments associated with the Pottery Project, a project that included assessment, preservation, rehousing, and research on more than 20,000 southwestern Native American ceramic vessels. The project was generously supported by grants from NEA, NEH, NCPTT, NAGPRA Grant Program, NSF, the Kress Foundation, the Stockman Family Foundation, and the Gila River, Salt River and Ak-Chin tribal communities, as well as by numerous private donors.

The authors have provided a worksheet (in both Microsoft Excel 97–2003 and Microsoft Access 2007 formats) as further information on the calculations used to derive the K(norm) values for ceramic desalination. Both formats are contained in a downloadable zip file.

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