Memory foam mattress left in rain and hot sunshine (need answer fast)

If a memory-foam mattress was accidentally left in rain and hot sunshine for a week , is it likely to be internally “degraded?” No longer usable?

It’s likely to be unaffected. Memory foam is a polyurethane it’s rather water resistant. Memory foam mattress protectors are a common item.

Mold growth might be a concern, if it smells bad steam clean it with a vinegar mixture.

Is it actually a mattress fully made out of memory foam? I’d be concerned that you’ll never get the middle of it dried out. Even after being in the sun for week, if you stand on it, does water still squeeze out of it?
I’d think your best bet (if it is just nothing but memory foam) would be to make sure it’s totally 100% dry. If there’s any moisture still trapped in there, I think your best bet is going to be to leave it in the sun during the day, wringing it out when you can (walk on it, roll it up and let it go, put some heavy weights in various spots, flip it a few times) and then at night bring it back in the house and maybe put a fan on it.
It’s already been a week, but the water in the center may need some help getting out.

OTOH, if it’s totally dry, no moisture that you can tell and it hasn’t already at least started to smell funky, you’re probably in the clear. FWIW, putting things out in the sun is usually a good way to help deal with mildew, so not dragging the water logged mattress into the house may have worked to your benefit.

Finally, if this is a ‘regular’ mattress with an inch or two of memory foam on top, just dealing with that little bit of memory foam is one thing, it’s the rest of the mattress that’ll be a much bigger deal.

Thanks. Does prolonged Sun heat (90 F) damage the memory foam?

If there’s gel inside the mattress, would it rupture?

Gel foams are not typically found inside and it isn’t something that can rupture, they sometimes use gel foam for the top layer. If gel foam gets saturated with water is can be very difficult to get back out. The gel foam is less heat resistant than the regular foam but it still takes much higher temperatures to damage it. 400degree range is where breakdown occurs.

The biggest concern you have it getting the water out, if it’s dry now you should be in the clear.


For sheer inquisitive sake - suppose the opposite extreme; freezing temps, what happens to mattress?

When mattresses are transported in cold weather, I doubt they are kept in heated trucks, so freezing temperatures probably wouldn’t be a problem. Or did you mean a mattress that gets rained on and THEN is exposed to freezing temperatures?

I had to wash the foam cushion from a couch, and had a lot of trouble removing the excess water. I rolled it up as best I could and sat on it. I even used a roofing roller (about 80 lbs) to try and squeegee it out. It was still pretty heavy.

So I took it to work and placed it in our vacuum chamber that goes down to 25 microns to evaporate the water. The rapid evaporation caused the water in the center to freeze!

Took forever to dry that darn thing out. I ended up putting it in a commercial dryer to help it.

Note: We did have vacuum ovens, they are fantastic for drying things. They will pull oil out of pottery dishes with cracks. I used them to help restore some vintage kitchen ware. But they are only about the size of a microwave.


If that mattress remembers what you did to it, you might be in trouble.