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Conservation > Ceramics

Summary

Ceramics are made with clay and then fired. Clay undergoes many changes in the process of being fired, and these changes make the ceramic ware stronger and harder. Ceramics are relatively resistant against chemical factors and environmental changes, but can easily be damaged by physical shock compared to cultural assets made of other materials. The conservation of ceramics consists of treating damaged ceramics and protecting them from any other possible external disturbance.

Types of damage found on ceramic artifacts

As most of us know, the most common type of damage to ceramics is breakage due to external shock. In addition, other types of defects from production exist, such cracking and deformation. Depending on the function of the work or the environment in which it was buried, peeling of the pottery glaze, salt weathering and discoloration can occur. Furthermore, if inappropriate material is used for conservation, staining or weakening may occur. Determining the type and extent of damage and establishing a plan for conservation can be regarded as the first step in ceramics conservation.

Various defects such as cracks, dents, swelling can result from inappropriate formulation of materials and failure to control the firing process

Example of natural damage caused by soil pressure and contact with roots of plants at the time of burial

Example of inappropriate conservation materials used in previous conservation treatments

Stains from prolonged use

Conservation of ceramics

Condition assessment

Condition assessment

Condition assessment

Prior to commencing a conservation treatment, an in-depth study is conducted to determine the extent of damage ceramic. First, we observe the extent of the damage, and condition of the clay and glaze. Then, we examine the cracks and restored parts of the interior of the ceramic piece using X-ray and ultraviolet ray imaging. Analysis of materials used in past conservation treatments are also conducted at this stage.

Removal of previous treatments

Removal of previous treatments

Removal of previous treatments

Ceramics are vulnerable to physical damage and thus many artifacts have had one or more restoration treatments throughout its lifetime. Adhesives and fills used in past treatments may deteriorate or change color with time. Therefore, it is sometimes necessary to perform re-restoration. Following a careful analysis to accurately identify the materials used in previous conservation procedures, these are removed safely from the ceramic artifacts.

Assembly of fragments

Assembly of fragments

Assembly of fragments

Fragments are assembled to restore the ceramic’s original forms to the best extent possible. Permanent gluing is executed only after the proper positioning of fragments is determined.

Restoration

Restoration

Restoration

Restoration is the process of reproducing missing portions to bring the piece back to its original form. Retouching and glazing treatments are performed to recreate the original appearance in terms of the overall hue and gloss of the work. As a material that is different from clay is used for the restoration of the ceramic piece, the new material used in the restoration process must be sufficiently verified to be stable. To ensure accurate restoration, a review of historical documents and historical research must also be performed through various means, such as a literature review and consultation with curators and art historians specializing in pottery should be preceded.