Memory foam  

very expensive stuff, grea...
very expensive stuff, great for the Eames Compact sofa
so of if you ever buy one on ebay and want to recover it use the memory foam great stuff!!
any other chairs it does get a little to pricey but if the customer wants it we get it,

Wouldn't sitting on Memory foam
be like sitting on a big breast implant? or a Water Bed?
I'm not a big fan of foam that doesn't function more like regular cotton batting.
I know that foam was the post war standard because it was spring-y and it kept its shape..that's until it got hard or started turning to dust.
I know that the new foam is synthetic and works very well, but if I had my choice, I'd keep the foam down to a minimum....

Foam
I was thinking of the basic two rectangular loose cushion chair, one seat one back. I'm designing a chair and wondered about how the memory foam would feel to sit on. I have a memory foam mattress and quite like it. Perhaps a composite cushion, one layer of standard, springy foam and a top layer of 10cm of memory foam?

more like down
I was hoping the visco-elastic foam would give a more "down" like seat than ordinary foam. Like sitting in a big, fluffy down cushion that magically returns to it's original (read neat and tidy) shape when you get up. I just have no idea how it might feel to sit on a whole chair of the stuff, except sitting on the edge of my bed, which seems nice.

i have talked to a lot of...
i have talked to a lot of people on this subject and from hanging around the old shop not many want to use the memory foam. I tried it on a mattress and personally i did not like it, I think for chairs that you sit in on every day I would use the tradional type first,

LRF -- what didn't you like...
LRF -- what didn't you like about your mattress? The heat?
Curious. I have always had reservations about this stuff.

I'm a big fan of memory foam ...
I'm a big fan of memory foam (I have an entirely foam bed). I tried stuffing memory foam into the cushion for my Poang chair. It's the most comfortable chair I have. You don't want to get up from it. The memory foam was probably about 3-4lb density, and cut from a memory foam mattress topper, and I believe layed over the original foam in the cushion. Unless you use a high density memory foam (ie. 4-5lb+), you might find using only memory foam to be a little on the soft side, and requiring regular polyurethane foam underneath.

good to know Entropy-o
i have a mattress topper memory foam not being used. It is folded and on a daybed in my
office. (elder dogs favorite sleeping spot)
The original previous owners left their custom sectional sofa. extremely well made and
debate about recovering or replacing. The cushions are down and a bit floppy. I think adding
a top layer of memory foam might correct the sinking factor?... Along with a good cleaning and
new fabric.
Any suggestions on another foam to test? latex?
Seems odd to put memory foam over down-fill. Is it not usually a batten layer inside the down?
(i said a 'bit floppy'...it is really a 'sinker!')

visco-elastic (memory) foam...
visco-elastic (memory) foam normally needs a firm support to do what its supposed to. You don't put it over top of down. If dense and firm enough, you may be able to use it on its own, in a sofa cushion. But in most cases, you will likely sink into the memory foam when you're on it (that's kind of the idea, that it conforms to your body shape). One advantage is that it returns to its original shape. (It's possible that over the years, the return factor will diminish. Less so, the denser the foam). IKEA uses latex foam over top of "cold foam" (high density polyurethane) in their Beddinge Lovas sofa mattress, IINM. Latex is said to be more 'bouncier' than memory foam, and since it makes a good bed, it should be fine for a sofa cushion. But its a lot more expensive than memory foam. If that's not an issue, one idea might be to just buy a Beddinge sofa mattress from Ikea and cut it up for cushions. The cheaper model without the latex uses "cold foam". My friend got the Beddinge sofa with this type of foam. Despite the fact that it isn't comforted by a layer of latex, I find it to be a good quality foam, perfectly fine for a sofa (though we did enhance it a bit with a layer of egg crate foam). In fact, I'm quite jealous of her Beddinge sofa every time I sit on it, because its so much more comfortable than my more stylish sofa (seems quite difficult to have both style and comfort....(sigh)). FWIW, IKEA labels this cold foam sofa mattress as suitable for sleeping on every day.

James
Yes It was hot, and to be honest i could not get used to it at all,
We tried it for 30 days and sent it back and got the pillow top, bed,
I know out in DA land some swear by it but it did nothing for me and the pillow was worse,
I kept it for 300 bucks from the sharper image but the stuff is just to dense, for me an my neck.
The only sofa that I really like it on is the Eames compact, and i sat on one in Palm Springs last week, I like it on the long untufted seat piece, for that it is just perfect.

I wouldn't recommend memory foam as a seat cushion, as it will be too soft and hot. Might get away with it for a back cushion though.