http://www.trueflightfeathers.com/facts.htm

If feathers get 'matted up' (been shooting feathers more than 50 years and have never seen feathers get THAT bad) just hold them over the spout of a steaming tea kettle for a few seconds. It's like magic. The feathers zip right back into shape all by themselves.

You can hold the feathers over a pot of boiling water and do the same thing, just the tea kettle spits the steam out under pressure and it works faster.