Cleaning Practices
Ceramics and glass objects should be kept free of dust, debris, and oily residues. In general, it is not a good idea to routinely wash these pieces. Each time a piece is handled for cleaning there is a greater risk of breakage through accidents and mishandling. It is better to protect pieces from soiling and dust in the first place, rather than wash them too often.
Porous ceramics, like earthenware, should never be immersed in water. They will absorb the water into the body like a sponge and draw surface stains of residues deeper into the ceramic body if left to soak. For cleaning any important ceramic or glass artifact, a conservator should first be consulted to ensure the objects stability and recommend safe cleaning methods.