Hi,
The outermost layer of our skin is covered with
sebum, which lubricates and waterproofs our skin. The
sebum keeps the water out when we wash our hands or take a quick shower. But when our skin is exposed to water for a longer time, the limited amount of sebum gets washed away. This is what happens when you take a bath, shower, swim, or wash the dishes. Once the sebum is washed away, water enters the outer layer of the skin by the process of osmosis.