Although memory foam pillows should never be machine washed, you can (and should) hand-wash your pillow when it's time for a deep clean. Simply submerge your pillow in lukewarm water along with some mild detergent and gently squeeze it a couple of times to allow the water to penetrate the foam. Never twist or wring your pillow because this can cause irreversible damage. Following this step, refill your bathtub or basin with clean water and give your pillow a rinse, gently squeezing until all the remaining dirt and soap has been removed. Once your memory foam pillow is clean, give it a squeeze to remove excess water and allow it to air-dry.