Electro-desalination of glazed tile panels – discussion of possibilities

Lisbeth M. Ottosen, Célia Dias-Ferreira, Alexandra B. Ribeiro

Research output: Contribution to conferencePaperResearchpeer-review


Glaze is lost from tiles in tile panels due to presence of soluble salts and this means loss of important heritage. There is no proven method for in-situ desalination of tile panels (inclusive the mortar and wall behind). The present paper discusses the possibility to apply electro-desalination. An in-situ test has not been performed yet, but encouraging results have been obtained with different parts of the system. Single tiles from different epochs and different places in Portugal have been electro-desalinated successfully (both biscuit and interface between biscuit and glaze). Electro-desalination has also been tested on a variety of porous stones (natural stones and ceramic bricks) in laboratory scale, and no limitations for salt removal have been in relation to the brick or stone type. Also successful desalination of the mortar on the back of a tile has been obtained. Thus all parts of the wall with tile panel can be electrodesalinated.
The interface between mortar and tile can be problematic for in-situ electro-desalination in cases where the tile is partly loosened. The interface needs to be in hydraulic contact meaning that there is a continuous liquid between the materials in order for the electric field to pass and subsequent the electro-desalination to progress. Few experiments were conducted with desalination of tiles with attached mortar. The electrodes were placed on the mortar, which was desalinated to a higher degree than the biscuit. However, whether successful desalination of the biscuit through the mortar could have been obtained was not confirmed. This is a point for further research.
In-situ pilot scale tests have been performed on very salt contaminated walls without tiles. Even though the final proof of concept has not been made yet, these experiments have illustrated, that it is possible to perform the desalination from electrodes which are all placed at the same side of the wall. This can be very useful in relation to electrodesalination of tile panels. It may be possible to desalinate without any physical damage of the fragile glaze by placing the electrodes on the opposite side of the wall or to remove some tiles, place electrodes in their spaces and extract the salts from there, before the tiles are placed in place again.
Original languageEnglish
Publication date2015
Number of pages14
Publication statusPublished - 2015
EventGlazeArch 2015: International Conference on Glazed Ceramics in Architectural Heritage - Lisbon, Portugal
Duration: 2 Jul 20153 Jul 2015


ConferenceGlazeArch 2015


  • Azulejos
  • Salt induced decay
  • Desalination
  • Electrokinetics


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