What can you do to a feather pillow that goes flat to puff it back up?

Try putting them in the dryer on low heat

I put mine in the dryer every week - no heat - for about 20 minutes. Also washing and drying but takes a long time to dry.

Feather pillows are washable! After all the feathers were on birds. I wash and then lay in the sun between beach towels to dry, then pop in the dryer on "fluff" with a few felted wool dryer balls.

I agree with the others. Washing and drying works. If you don't want to wash them fluff in the dryer.

I kinda punch and shake them to fluff up.

I have read to wash them and then dry them on very low with a clean tennis ball. And they can be put in the dryer with no heat with a tennis ball more often than they are washed. It apparently makes quite a racket, but produces nice, fluffy pillows.

You can do all as suggested above, but if your pillow needs more feathers, it still needs more feathers. I would do as other say and then assess the clean and fluffed pillow. If it still seems flat add feathers and/or down. Even if it means deconstructing another pillow.

I agree with other comments, but if you still need more, just try to gather as many feathers within the pillow to one end, cut off the extra fabric and sew up the end. Your pillow will be smaller...but smaller can be good, too!

my dog gets ahold of mine, shakes it up pretty fluffy, lol!

Throw the pillows on the floor to break up clumps and clusters. Beat them on top with your fists repeatedly. Flip them over and beat the other side. Then pump the two ends together like an accordion. They ought to stay fluffy for two or three nights, but it’s better to fluff them daily. 😇

You're welcome.