Foam pillows are often used for their anti-allergenic properties but, like all bedding, need to be cleaned regularly. When wet, foam can be easy to tear, so always clean the pillows inside their ticking cases.
Problems with Machine washing
Because of their size, most pillows are not suitable for machine washing unless you're prepared to do them one at a time. A front loading machine could possibly appear to be big enough for two or three pillows, but the amount of room in the drum and the quantity of water the drum can contain will seriously reduce the efficiency of the cleaning process. To be washed thoroughly, a pillow must have the washing water it contains exchanged several times. Another problem is that a machine with an automatic spin cycle after the wash and rinse cycles will be very unbalanced with a slow draining foam pillow inside. This could cause the machine to abort the spin cycle or vibrate so badly that the machine will rattle across the floor.
To hand wash a foam pillow you need to have a large and deep tub that will allow you to manipulate the pillow in the water. Fill the tub with warm water and add a mild liquid soap. Submerge the pillow and knead like you would flour dough for bread. Make sure to squeeze gently but firmly, to expel all the air initially and then to exchange the soapy water.
If there are stained areas on the ticking case, these can be given special attention using a soft scrubbing brush and additional liquid soap.
Replace the water in the tub with warm clean water and rinse the pillow thoroughly to remove all the soapy water. Replace the warm water with cool water for a final rinse. The final rinse can also have a little fabric conditioner added to give the pillow a pleasant smell.
The foam in the pillow will readily give up most of the water it contains if it can be laid on a draining rack. Squeezing the pillow gently will help to speed up the water loss and also enable you to re-shape the pillow if necessary. Once most of the water is removed it can be hung out to dry on a clothes line. A sunny, breezy day is the best for this. Hang the pillow from a long side rather than from the end.
Don't try to rush the drying process by using an electric drying machine. Foam is an insulator, so the heat from the drying machine will only affect the outer surfaces of a solid foam pillow. Even in a pillow containing foam pieces, the insulating effect is very efficient and pieces in the middle of the pillow might not be dried at all.
Foam pillows can give several years of good service, and regular laundering will keep them clean and smelling sweet.