We report the first measurements of mass gain and expansive strain in clay ceramics immediately following firing. The results show that both mass gain and expansive strain follow a well defined two-stage process, each stage of which is linear with (time) 1/4 , with a transition from the first to the second stage commencing at t ∼ 1.5 h. The first stage mass gain and strain rates are ∼3.5 times greater than the second stage rates. The strain is found to show the same linear relationship with

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... throughout both stages providing evidence that the underlying physical process is the same in each stage. The early time measurements are unique in providing experimental evidence for t 1/4 kinetics for both strain and mass gain over times ranging from minutes to days and are consistent with earlier strain data showing t 1/4 kinetics over times ranging from days to centuries.