Simple Science
Why do your fingers wrinkle
in the bath?
At a glance
Water can move into
the dead upper layer
of skin cells
The water causes the
cells to expand
The only way that the
cells can continue to
cover the same area is
for them to rearrange
themselves
Some of the cells are
pushed upwards
others are pushed
downwards
This causes your skin
to wrinkle
As you dry out the
water will move from
the bloated cells
causing them to
contract and your
fingers to unwrinkle
It’s nature’s original way to
tell you to get out of the bath
but why do our fingers
wrinkle
in
the
bath?
Thankfully this phenomenon
is only temporary and our
fingers will rapidly return to
normal. The cause of this
wrinkling is truly skin deep.
Unwrinkled Fingers
Upper skin cells
Lower skin cells
Wrinkled Fingers
Swollen upper
skin cells
Normal lower
skin cells
The outer layer of our skin is in fact made up of a layer of
dead skin cells. These cells act as protection for the new
skin growing underneath. Water will naturally move from
an area with a lot of water to an area without as much
water. This process is known as osmosis. When you sit in
the bath, water will move from the bath into the upper
skin cells. As the cells absorb water, they expand and
push into each other causing the skin to ripple. This
effect is most noticeable in the areas where you have the
thickest layers of skin. Our hands and feet are constantly
rubbing against surfaces and so we have thicker layers of
skin on these regions. This means that the wrinkling
effect is strongest in these areas. Once you’re out of the
bath, the cells dry out, contract and the skin unwrinkles.
Centre for Lifelong Learning
Alex Brown, 2012
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