Standards Development

Scope

This European standard specifies a method for the desalination by poultices of porous inorganic materials constituting cultural heritage. The desalination methodology may be applied to salt loaded porous inorganic materials either affected by salt weathering and/or to allow conservation treatments incompatible with soluble salts contamination. In both cases the desalination aims to decrease salt contents.

Furthermore, this European standard gives the fundamental requirements of the desalination operation and guidelines for the choice of the most appropriate poultice components according to the characteristics of the substrate in order to optimize the desalination rate.

Purpose

Salts are often present in stones and other porous inorganic building material as alteration products of chemical, biological or anthropogenic origin. They can originate from surface deposition of atmospheric pollutants, from capillary transport or from external sources and from the material itself, and may be present due to previous, unsuitable, restoration interventions. Salts can damage the fabric of porous materials and lead to different decay feature of the object sometimes causing substantial loss. The amount of deterioration and its appearance depends, for a given material, on the rype of salts crystallizing, the amount of salts present and the environment conditions.

Reduction of the salt content is an essential prerequisite for reducing the deterioration rate of the object and for the success and durability of a conservation measure. Before any intervention/application to reduce salt damage shall be carried out, investigation and relevant interventions to prevent moisture penetration shall be considered as part of a holistic conservation approach.

The proposed standard describes a procedure to reduce soluble salts present in a porous inorganic material by a process of poultice desalination, outlining the requirements for the selection of poultice components and the procedure for application and monitoring the desalination.

Desalination by poultices refers to a removal of salts, i.e., their ions, from the pore system of porous inorganic materials such as natural stones, bricks or terracotta, renders/plasters, or wall paintings. Treatments can be carried out in situ, or in a restoration workshop for movable objects.