Cut memory foam pad = still comfy?

June 4, 2006 8:25 AM

Would a memory foam mattress topper be uncomfortable if it were cut in the middle?

I've switched to a memory foam-based bed a couple of years ago and have never been happier with my bed.

I want to buy a 3" 5lb queen-sized topper for me and my girlfriend, when we travel, and cut it in half (as they can be packed away in a very small container if the air is sucked out). This sounds perfect, except it would be nice to be able to reassemble the two halves on a queen-sized bed. My experience with the material is enough to say that it seems at least plausible that we wouldn't notice the cut in the center, but I really don't know. Anyone have some more experience with memory foam?

posted by sirion to travel & transportation (9 comments total)

I know someone who sleeps on a twin cut out of two kings, so it can be done. I don't remember them having to do anything odd to cut it, so for all I know, just go for it.
posted by Hildago at 8:49 AM on June 4, 2006

I bought a queen topper from ... damn, some company that I found in an answer on the Green, but I can't find it again. Anyway, it's a knock-off of the Tempur-pedic foam (the patent has run out, I believe, so anybody can make it). I liked it, but Mrs. Spacewrench didn't, so I cut it in half and she just sleeps on the mattress.

The foam develops tears pretty easily if you move it around, but if you put two torn pieces next to each other and cover with a sheet, you can't tell there's a break.

The foam is pretty heavy, though; I'd be surprised if a 3" queen-sized slab of it only weighed 5 pounds. Maybe you've got a different material on your hands?
posted by spacewrench at 12:00 PM on June 4, 2006

Just a caution regarding cutting or tearing memory foam:

The molecular reason that memory foam works is that the molecules are aligned in a manner that is the most efficient. You apply stress to the foam structure when you lay on the matress; when you get up, the stress is released and the molecules are inclined to return to the most efficient configuration, which is how the foam manages to keep its shape. Kevlar (such as found in bullet-resistant vests) actually works according to the same principles.

When the overall structure is disturbed or changed, such as by cutting, tearing, puncturing, or even high temperatures, the molecular configurations can change and result in the material degrading and losing functionality over time.

I'm not saying that you'll instantly have problems, but I would suspect that the longevity and usefulness of the foam will be diminished over the lifetime of the product as compared to an unadulterated sample. Just a consideration to take into account.

Disclaimer: I am a chemical engineer, but I do not work with memory foam.
posted by galimatias at 6:40 PM on June 4, 2006

A clarification on my earlier post:

The molecular effects that I mentioned will occur at the site of the tear or cut, not throughout the memory foam. However, with time, I would expect some propagation through the remainder of the structure.

Also, to answer your question without such a digression, you shouldn't have a problem cutting the foam as you described. If replacing it after a few years is not a major concern and you're not buying an expensive piece, by all means go ahead and do it.
posted by galimatias at 6:44 PM on June 4, 2006

Cool Tool: Visco-elastic Memory Foam


In terms of working with it, it seems to be just like ordinary foam except slightly heavier. I cut a slice off my mattress overlay with scissors: no problems, nice clean cut.

posted by bleary at 6:58 PM on June 4, 2006

They have to cut the foam at least once anyway, right?
posted by Hildago at 8:16 PM on June 4, 2006

I'm not worried so much about cutting it (I cut my own memory foam pad down to size last tim). I'm wondering about reassembling it and not feeling like I'm on two mattresses
posted by sirion at 8:28 PM on June 4, 2006

Hildago, most foams are initially set in a mold so as to not require any cutting.
posted by galimatias at 8:31 PM on June 4, 2006

Sorry, sirion, for the digression.

One thing you might want to do is get some cheap velcro and line the seam and the bottom with it. That way, you can keep the two sides linked together when you want them together, but allow for easy separation when you travel.
posted by galimatias at 8:34 PM on June 4, 2006