Carbon Fiber GMC

It is to protect the resin (binders) more than the fiber, whether it is glass fiber or carbon fiber (carbon black dust is employed as the UV protective material in many things...like tires)

Also to be the sacrificial protective layer for the resin/binders against UV and O3 damage...

Also, there is a difference between sacrificial coatings....Clear coat is paint and the gel coat on fiberglass/CarbonFiber is clear/colored resin