Hidden prompt splashing by corona splashing at drop impact on a smooth dry surface

We present the experimental evidence of prompt splashing due to surface roughness at drop impact on a dry smooth surface, by suppressing corona splashing due to the surrounding gas. Prompt splashing occurs during a very early stage of the impact process, and it cannot be suppressed by reducing the gas pressure even to 0.8 kPa. We evaluate the conditions under which corona splashing hides prompt splashing at atmospheric conditions. We also demonstrate the importance of the distinction of two events, i.e., prompt splashing occurs and it can be clearly distinguished.