I've been slightly obsessed with learning about the Purple mattress and cushioning technology, and dang, it's so interesting what they've done with it. I almost wanna dive into the math behind the column buckling to see if I understand it more.


How does it differ from Casper and the other mattresses? All I remember was that egg video but none of the details other than being somewhere between a box-spring and memory foam.

@zzz Most mattresses, including Casper, are made of foam. Some fancier mattresses are made of memory foam. But purple is a totally new technology for doing cushioning.

It has this weird gel grid thing on top that has some fascinating properties. The end result of which is that your heavier bits tend to sink deeper into the mattress but with the same pressure on them as on other parts of your body that don't sink as far.

@zzz Their gel grid thing feels a little weird if you're not used to it, but it works wonderfully.

A way to think about it is that the grid is arranged in a series of strong columns. When multiple columns support you, the load is distributed evenly among those columns and support you well.

But if a particular area is heavier, like your butt, hips, or shoulders, they cause those columns to "buckle" and collapse, reducing their support to just the elasticity of the material.

@zzz So it has this weird aspect of like, feeling really soft for some parts of your body. where the columns have buckled, and nicely firm where the columns still stand. That mixture winds up cradling your body in a way that is a bazillion times more comfortble.

And no one else really has cushioning tech like that out there.

The two brothers that invented it started with wheelchair users to reduce pain for sitting for long periods. This is an evolution of that invention.

@zzz The "egg test" thing they do is a way to communicate how this works. Basically, you can support a MASSIVE amount of weight on it if you spread that weight out over the bed, but while doing that, localized "hot spots" of weight just kinda press into the thing without a lot of pressure on them. So the big weight is held up, but the egg is softly cradled underneath that weight.


Oh that's fascinating. I had a latex mattress a few years back that molds around your body but it was actually very hard to get out of bed.

@zzz That's one of several drawbacks of this thing. In the more recent models, they've added foam blocks on the edges to improve that, and I'm pretty happy with it.

This mattress may "mold around your body" but it springs right back into shape after you move off of it, so you can still get support to push yourself up and stuff.

@zzz The science of all this stuff really fascinates me.

The problem with typical foam is that it works by having resistance to compression. So you can compress it, but it responds to that compressioon with pressure, trying to return to its original shape.

Memory foam works by "holding its shape" and reducing pressure to decompress, so those areas that get compressed stay compressed and offer less resistance.

I'm not sure how that latex mattress you're talking about works...

@zzz So foam = higher pressure on higher weight areas. Memory foam doesn't do that once it's compressed for a bit, but it has the unfortunate side effect of responding to heat and causing you to sink and get stuck. Making it hard if you flip around a lot at night like me.

Purple resists compression through two methods. The columns and the elastic decompression pressure. The columns hold you up through distributing the weight. When you cross a threshold, they buckle, and the elasticity enters.

@pandora_parrot I think latex works similarly to memory foam but doesn't hold its shape as readily as memory foam. It certainly doesn't have this grid the way purple does.

@zzz yeah. The grid, combined with the “hyper elastic polymer” they use for it, really makes for a very unique mattress.

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