Fiber glass prevents "wicking" of moisture underneath the coating.  This means Wet-Jet roof coating made with fiber glass will last much longer than ordinary coatings using cheap "fillers".  Moisture is the deadly enemy of roof life.  It becomes dangerous when it gets underneath the roof mat.  As long as the coating and roof mat offer a solid barrier resistant to penetration, there is no problem.  When a break develops, even an opening the size of a pin prick, moisture creeps in. Roof protection begins to break down.

Cheap fillers provide easy access for water to funnel down to the roof mat.  This is a gradual process.  It takes months to complete the process of drawing moisture underneath the film of coating.  This action of fillers can be compared to the wick in an old-fashioned oil lamp. Once the fillers start wicking water under the film of coating, roof protection is lost.  Breaks in the coating and roof mat occur causing leaks.  Heat from the sun turns the trapped moisture into steam which in turn forms blisters which further weaken the roof mat.  This cycle of deterioration cannot occur with Wet-Jet made with fiber glass.  Fiber glass is not tubular.  It cannot absorb moisture.  It cannot funnel or carry water through and under the roof coating. Its value cannot be over emphasized as a means of providing extra years of life expectancy.