For reference, I have two old Frostline down items I made 35 years ago. One is a Cougar sleeping bag, the other a simple vest. Both items received the same down fill (no quills). The bag has only been washed once since I used it with a silken liner and appears to have its original loft (yes it smells a bit weird right now). On the other hand the vest has maybe a third of its loft and has gone through many machine wash cycles with general laundry detergent. I would guess that the agitator of the wash machine is what killed the vest, probably ripping the down filaments when they were wet.