What makes kitchen plastic wrap cling so maddeningly to itself, and so conveniently to the sides of bowls and plates?
Plastic wrap clings for two reasons: it’s elastic and it’s sticky.
That probably seems pretty obvious, but let’s explore the chemistry beneath the elasticity and stickiness of plastic wrap.
Plastic wrap is elastic because of its molecular structure.
A molecule of plastic is incredibly long and coiled up like a spring.
When you stretch out a piece of plastic wrap, you uncoil these long molecules.
Like a spring, the stretched molecules tend to spring back, perhaps tucking under the rim of the bowl you just covered!
Over time, certain types of plastic wrap lose some of their elasticity, which could explain why that dish you wrapped tightly may loosen up after a day or two.