  When an object impacts the free surface of a liquid, it ejects a splash
curtain upwards and creates an air cavity below the free surface. As the object
descends into the liquid, the air cavity eventually closes under the action of
hydrostatic pressure (deep seal). In contrast, the surface curtain may splash
outwards or dome over and close, creating a surface seal. In this paper we
experimentally investigate how the splash curtain dynamics are governed by the
interplay of cavity pressure difference, gravity, and surface tension and how
they control the occurrence, or not, of surface seal. Based on the experimental
observations and measurements, we develop an analytical model to describe the
trajectory and dynamics of the splash curtain. The model enables us to reveal
the scaling relationship for the dimensionless surface seal time and discover
the existence of a critical dimensionless number that predicts the occurrence
of surface seal. This scaling indicates that the most significant parameter
governing the occurrence of surface seal is the velocity of the airflow rushing
into the cavity. This is in contrast to the current understanding which
considers the impact velocity as the determinant parameter.
