The test results show that the quicker the initial set of plaster the greater the difference between the initial setting times of the plaster with addition of s type retarder.

试验结果表明，所用建筑石膏的初凝时间愈快，掺有S型缓凝剂后其初凝时间差愈大。所以，初凝时间差不宜作为石膏缓凝剂的缓凝效果指标。