Why are some shipwreck ceramics not as glossy as antique pieces found elsewhere?
First of all, be careful with “antique” ceramics that looks new. It is pretty obvious that any historical artefacts will have some evidences of use. Earlier high-fired pottery are most often covered with a glaze containing iron oxides. If the ware is not fired at sufficiently high temperature to fully dissolve iron oxides in the glaze, it will crystallize on the surface. Once in contact with salt water, the crystals corrode, slowly pit the surface and eventually ‘wear’ the surface. The amount of deterioration often vary dependent on the duration of stay on the seabed. This effect is in fact, proof that the piece is old and that it has been recovered from the sea.
