When polymers — such as plastics — experience stress, one of the most common reactions is a color change: they turn white at the point of stress. … Heating a polymer can cause the amorphous sections of the chain to crystalize. When that happens, the way the molecules scatter light changes and the plastic turns white.

How do you remove white marks from black plastic?

Make a solution of water and bleach, using one tablespoon of bleach per cup of water. Let the containers and other items soak in the solution for one or two hours. After the stains are gone, wash the containers thoroughly, rinse, and dry.

Why is the plastic on my car turning white?

Why Does Black Plastic Fade Over Time And Turn White? … Over time, those oils near the surface degrade and dry out, leading to discoloration. Unlike paintwork, plastic trim pieces don’t have a protective clear coat. So, without this layer of defense, it will always be more susceptible to damage from the elements.