Just as paint brush bristle type is dependent on type of paint used, the same applies to roller naps.
+ Nylon and wool blend naps are to be used with alkyd paints.
+ Nylon only naps are required for latex paint usage.
Nap length (thickness of fuzzy stuff)
+ Use a shorter nap for glossier and smoother surfaces.
+ Long roller naps are better for textured surfaces where you need better coverage like brick and stucco.
+ Plastic nap cores are of higher quality than cardboard and don’t lose their shape and can be used repeatedly.