The subject of curing materials was first discussed by John Swanberg in ASTM STP 169 in 1955. In 1966, C. E. Proudley wrote about curing materials in ASTM STP 169A. The discussion on curing materials in ASTM STP 169B was by Rodger Carrier. This paper attempts to summarize the extent to which the state of the art has changed over the years since 1955.