Abstract
1) The water-powder ratio of Type II was influenced by the specification method and the kind of plaster, and a constant relationship was observed in this method. This relationship was not recognized in Types III and IV.
2) With a cosistent water-powder ratio, the setting times of all plasters tested in this study increased in the sequence of JIS, ISO, ADA, despite the kind of plaster used. When the water-powder ratio complied with standard testing consistency, the setting times of Type II increased in the order of ADA, JIS, ISO, but Types III and IV's increased in the sequence of JIS, ISO, ADA.
3) The working time of Type II was 2.20〜2.30 minutes. For Types III and IV, it was three times as long as Type II.
4) In case of practical testing consistency, the relationship between the working time and the setting times was recognized; the working time was shorter than the setting time by about 20〜31% in Type II, and by 53〜82% in Types III and IV.
