A comparison of methods for determining setting rate of amalgam

Four methods were compared for determining the setting rate of amalgams. The resultant order of preference as a standard method was compressive strength at 30 minutes after preparation of the specimen, the time to the last transverse cut on a cylindrical specimen with a "guillotine" blade and the time to nonfracture of a ball of a amalgam with a final set Gillmore needle. A mercury absorption method was unacceptable. Alloys labelled fast and standard setting could be separated and limits between fast and standard alloys have been examined for each method.