Aluminium amalgam of mercury are not allowed aboard aircraft under most circumstances because of the risk of it forming amalgam with exposed aluminium parts in the aircraft. Even the transportation and packaging of mercury-containing thermometers and barometers is severely restricted. Accidental mercury spills in aircraft do sometimes result in insurance write-offs. Aluminium amalgam Aluminium can form an amalgam in solution with mercury. Aluminium amalgam may be prepared by either grinding aluminium pellets or wire in mercury, or by allowing aluminium wire to react with a solution of mercury(II) chloride in water. This amalgam is used as a chemical reagent to reduce compounds,
Amalgam (dentistry) conservative preparation would be beneficial, composite is the recommended restorative material. These situations would include small occlusal restorations, in which amalgam would require the removal of more sound tooth structure, as well as in "enamel sites beyond the height of contour". For cosmetic purposes, composite is preferred when a restoration is required on an immediately visible portion of a tooth. Dental amalgam does not by itself bond to tooth structure. This was recognized as a shortcoming by early practitioners such as Baldwin. He recommended that the prepared cavity be coated with zinc phosphate cement just prior to filling with amalgam,