It is the humidity in the air and the moisture from the body that contributes to the reduction of loftiness in pillows or cushion inserts.
Easy solution.--- let them lie in the sun for 30 minutes every few weeks and you cushions or pillows will last much longer, I will write how to keep the down feather products plump after i research it thoroughly.. I tried using the sun, it works better than the dryer for some reason.
