I'm sort of recycling part of a previous post . Recycling is good though, right? ©Science-y Hair Blog 2013 Full sunlight on your hair can be bad news if you get too much. When hair is exposed to 200 hours of ultraviolet radiation from sunlight, the cuticle edges begin to fuse and as a result the total cuticle surface “shrinks.” As it shrinks, tiny openings are created where cuticle once was and these are known as "porosities." It's like putting a piece of plastic on a hot stove or in the oven - it shrinks as it heats and as it is assaulted by ultraviolet light. After 400 hours of ultraviolet light / sun exposure, porosity continues to increase with further cuticle damage. After 1200 hours, the cuticle becomes rigid, brittle, and may crack under stress, leading to even further increases in porosity. ©Science-y Hair Blog 2013 If your hair grows the "average" of up to 6 inches per year (15 cm) and you get sunlight for even half an hour per day, during half...