Deterioration

The most common ceramic conservation problems include:

• breakage;
• deterioration of previous repairs;
• flaking painted decoration or glaze;
• soiling or staining;
• loss and cracking; and
• damage from salt efflorescence.

Damage from salt contamination may occur in unwashed objects recovered from buried or underwater sites. As the object dries, chloride and sulphate salts form crystals which expand and break up the ceramic. Signs of salt damage are white crystals on the surface, shallow pits on the ceramic body or missing spots of glaze (Figure 1).

Figure 1: (a) Surface damage due to salt contamination on a small ceramic jar.
(b) A ceramic plate that also has surface damage due to contamination from salt.