The coating is the non-glass protective material applied to the fiber. It is most commonly a dual layer acrylate, with a soft mechanically isolating inner layer and a tougher outer layer.
The outer coating, also called secondary coating, is the most external layer of coating material applied to the optical fiber. It is essential for the outer coating to offer both good mechanical and chemical protection to the optical fiber against the environment and also good bonding properties to the inner coating, so delamination in between the layers is avoided.
Related Terms: Coating, Fiber