Halfpint, I soften my ducks by putting them in washer for a 1/2 hour wash cycle with a cup of Downy fabric softener only. Hang dry with straightend pleats ( I use weighted wooden clothespins ) Then tumble them in a cold dryer for 15 to 30 minutes with 12 tennis balls. After the first wash and soften round, I just use Downy in the rinse and the tennis ball routine.
They come out quite soft from the pounding. Being cotton duck, a bit of touchup iron work is required at times.