Always follow the manufacturers recommendations for care of your pillow. The filling will dictate proper care. Memory foam and latex are generally not washable. Look for removable and washable covers when you buy this type of pillow. Submerging your memory foam pillow in water can damage the longevity of it. Down pillows may not recover well from being machine washed, especially if they are not dried fully. Check with the company you purchase your new pillow from for specific washing procedures. Oftentimes, the washing instructions for the pillowcase will be different from the pillow and allow light machine washing. Always make sure to air dry your pillows and pillowcases to prevent shrinkage.