抄録
It has been found by the present writer that the initial sharpness of finished cutleries degenerates as time elapses. The string cutting value goes down rapidly in 4 days and thereafter the change becomes very slow.It takes 16 days for the degeneration of the paper cutting value to become very slow.The time-sharpness curves were taken with various samples under various conditions. 30 minutes′ heating at 100° is sufficient to produce remarkable degeneration of the sharpness.The degeneration of sharpness means the increase in the radius of curvature of the top edge of the blade.The change may possibly be considered to be physical. But the writer is inclined to conclude that chemical change is the important factor in the degeneration of initial sharpness of cutleries by ageing.
