Originally Posted by cameront120
Actually, fibreglass insulation will retain water. Mineral wool is hydrophobic and will not retain water and, therefore, makes for a better product in trailers or any situation where water might be present.
I suspect that a hydrophobic character is much dependent on what is used to bind the fibers in the batting. According to Wikipedia, mineral wool is used in hydroponics:
"Mineral wool products can hold large quantities of water and air that aid root growth and nutrient uptake in hydroponics
In other words, probably any glass-fiber product could be made nominally hydrophobic. Even so, with a dense batting, water will be retained.