Well-made felt is already shrunk to its final density during the felting process and will not shrink further unless washed in hot water. Surface shedding is minimal and stops after the first week, this is loose fiber working its way out. If a felt product sheds heavily ongoing, it was under-felted (common in cheap mass production); ours are rolled long enough to reach a density of roughly 0.25 g/cm³, which locks fibers permanently.