I have had a feather pillow and a down pillow since the '90's. Both go into the washer once a year. If washing just one, put something equally as heavy (when wet) to balance the tub (blanket perhaps) and set the fill level to large because they soak up a lot of water. Wash on delicate cycle. Keep your ears pealed for any signs of an unbalanced load...when done, put into the dryer on a low setting with either an old (but clean) sneaker or a tennis ball or two. These beat the feathers as it goes around and fluffs and dries them faster. Also can be done for a down comforter. FYI, this is all from Martha Stewart, who knows her stuff. Check over the pillows casing before washing and repair any tears (they really will fall apart if not mended before a wash).
I don't think it is advisable to launder them. Maybe ask someone at a cleaners if they dry clean them. My daughter tore a feather pillow open when she was 4 years old, and the whole room looked as if it were hit by a huge snow storm. Before I'd take the chance of laundering my feather pillow, I will probably just buy another pillow, unless you want feathers everywhere. LOL.
make it tight with rubber band so it won't get off the feather out. or you could use plastic bag to hold those feathers together and wash it with your hands.. that way it all feathers stick together. i recommend to use detergent because it make your pillow whiter
Put them in the dryer on low heat with a wet/damp towel and a dryer sheet. This will freshen your pillow. Do not put them in the washer! Over time it will clump and then eventually disintegrate the feathers. Have had a feather pillow for years...and it is just as nice as the day I bought it.