Why Sperry (and Other Boat Shoe) Soles Harden, Dry Out, and Become Slick

Sperrys (and other boat shoe soles) dry and harden, become slick,  and eventually crack because of two reasons:

1. You wear them while cleaning your boat’s deck with bleach or a similar chemical.  Bleach “dries out” many rubber polymers.  In years past, celebrating race car drivers and burnout enthusiasts applied bleach to their tires to quickly “dry” and harden the outermost edge of their tires’ rubber, which would cause the tires to loose traction easier and make doing burnouts easier.
2. You only wear them while on your boat(s), so that the outermost portion of the hardened sole never wears away.

ENTHUSIASTS HARDENING RUBBER POLYMER WITH BLEACH FOR BURNOUT