DETERIORATION OF CERAMICS

Great care is needed when handling ceramics. However robust ceramics may appear, they become more fragile with age. Sometimes the joins between the handles and the body of a pot weaken and they may break if treated as though they were modern pottery.

The main hazards for ceramics are soluble salts, pollution and poor handling. Wood and wood products give off pollutant gases, such as acetic acid, which can react with salts within the body of the ceramic. This results in crystals forming under the surface and their growth is accelerated by fluctuating humidity. Eventually the crystals break through the surface (effloresce) forcing it to split and flake.

Some old repair methods have caused damage in the long term. In some cases inappropriate adhesives were used which have been found to discolour and shrink on ageing. In shrinking, a layer of the ceramic can be pulled away from the body of the pot. Today's conservators have a wide range of adhesives from which to choose. Those used with ceramics will usually be weaker than the ceramic body which prevents the ceramic from breaking, rather than the adhesive, if the object is put under stress.

Light is not harmful to ceramics as such, but pigments used in surface decoration could be damaged by over-exposure. Restorations on ceramic objects can quickly fade or yellow if over-exposed to light.

ceramics
Salt crystals on a ceramic

 

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