Does Memory Foam Absorb Moisture?

Memory foam beds are all the rage, and rightly so. They provide a great, pressure-free sleep surface and can be very supportive. However, like anything, they have negatives as well, such as cost, off-gassing and heat build-up. One question I get often is about moisture and memory foam. Specifically, if getting memory foam wet will affect it and how to prevent it from getting wet. Does it absorb it like a sponge?
Read any mattress warranty and you are likely to see a clause about stains voiding the warranty. That is because moisture is the worst enemy of a foam mattress, for three reasons:
  1. Moisture can hasten the deterioration of foam and affect its performance
  2. Moisture can weaken the adhesive holding the layers together and ruin the mattress
  3. Moisture can accumulate and lead towards mold
So, knowing this information, you want to take every precaution to keep moisture out of your new memory foam mattress. One of the first things I always recommend to customers who purchase a non-toxic Bed in a Box.com memory foam mattress from me is to add a waterproof cover. Now, these are non-toxic and breathable waterproof covers, so they don't make you sweat. But keeping fluids of any kind starts by adding a cover.
Another thing I recommend is "un-making" your bed in the morning. Doing this allows the mattress and bedding to dry out during the time the mattress is not used. Make your bed as usual, then fold all the covers back, exposing the sheets to the air. Making the bed does nothing except trap the sweat and moisture from our body, providing moisture for dust mites to live on, but also allowing it to accumulate in the mattress and in the foam.
Keeping your new memory foam mattress dry and free of spills and body fluids is important for keeping it in optimum condition and keeping your warranty intact. Memory foam is very porous and will not soak up moisture but it will seep down into the foam and stay there if it is not properly ventilated. If you live in the Berkeley, San Francisco or North Bay area where there is a lot of moisture in the air to begin with, practicing these tips will help keep your mattress free from moisture.