RECORDING MEDIUM

摘要

A recording medium is provided which includes a microporous thermoplastics film having a fibrillar or reticulated structure and a contrasting underlayer. Impact on the microporous film causes it to change from an opaque to a clear state revealing the contrasting underlayer. The medium may be used to reveal impact e.g. of a golf ball on the head of a golf club to which it is attached, it may be printed in an impact or thermal printer or it may be used to detect temperature rises above a characteristic limit at which the film becomes transparent.