Desalination For Preservation Of Murals By
Electromigration And Regulated Climate
Author(s)
I. Rörig-Dalgaard
Abstract
The presence of salts is a threat against the preservation of cultural heritage, e.g.
murals. The volume change from dissolved salt (ions) to precipitated salts results
in crystallization pressure. This crystallization pressure can result in deterioration
when the crystallization occurs underneath the surface, resulting in deterioration
of the overlying material. The crystallization occurs most often in the
evaporation zone, close to the surface, e.g. between the brick masonry and the
lime layer with paintings.
In the present investigation it was aimed to improve the electromigration (ion
transport in an applied electric field) desalination efficiency of a wall section
with murals by regulation of the surrounding climate. The idea was to obtain a
relative humidity (RH) above the polluting salts deliquesce point (NaCl ~ 76%)
to ensure the presence of dissolved salt (ions). A humidifier was used to create
high relative humidity and the actual RH was followed with a hygrograph.
After two weeks of treatment with an applied electric DC field and regulated
climate, the average chloride content for all brick and mortar samples was
decreased from 0.6 wt% to 0.1 wt% and for all the brick samples from 0.53 wt%
to 0.06wt% on average.
The present experiment clearly showed the necessity of a relative humidity
around the polluting salts deliquesce point in order to dissolute the salts before
they can be transported in an applied electric DC field. Significant desalination
was obtained in all the positions within the same range as seen in previous
experiments with capillary saturated single bricks.
Keywords: desalination, electromigration, regulated climate, murals.
Keywords
desalination, electromigration, regulated climate, murals
Related Book
Other papers in this volume
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