Always check for holes or ripped seams first, and repair them before attempting to clean.
Down and feather pillows can be dry cleaned, and will retain their softness and fluffiness.
If you put down or feather pillows in the washing machine, do two at a time or one with a few towels to balance the load.
Use cold water and the delicate cycle, with a gentle detergent like Ivory Snow.
If you hand wash, do the same, but use ½ cup vinegar in your rinse water to make sure all the soap dissolves away.
To dry, put pillows in on lowest heat setting or no-heat tumble dry. Add a few clean tennis balls or shoes to fluff them in the drier. This may take three hours or more.
Make sure down and feather pillows are completely dry before using or storing. Mildew can grow inside and ruin them.
Do not over-clean down or feather pillows. The natural oils in the material will be stripped over time.