A measure type for recording volume loss or mass loss in materials testing, particularly for syneresis (liquid expulsion from gels). Can be expressed either as volume loss (volume per volume, such as %) or mass loss (mass per mass, such as %). This dual capability allows flexibility in reporting depending on whether volume or mass change is more easily measured. Commonly used in clay mineral studies, grout testing, and soil-water interaction studies.

The unit of measure for volume or mass loss. Can be a volume ratio (m3/m3, %, etc.) or a mass ratio (kg/kg, %, etc.). The choice depends on whether volume change or mass change is being measured.