Specs for foam/cushions on Knoll Womb?  

the cushions can be remade...
the cushions can be remade just take some of the stuffing out and it will be perfect. The upholster will do that for you with no problem.

Thank you all!
Spanky- thanks for the informative post - it was really helpful! I am really curious about the ILD of my current foam because it does not compress much at all compared with every other cushion in my house.
You've really piqued my curiosity about the latex foam rubber - is this something I can find at any foam/fabric store? I'm tempted to indulge...
And thanks so much for tip on the back cushion being softer - again, I never would have known!
LRF - this is good to know - thanks for weighing in.
I really REALLY appreciate you guys taking the time to respond. Like Mark said, I have learned so much about the womb chair on this thread. I'll make a note of what foam I end up using and report back when finished. Thank you!

latex foam
Unfortunately, you can't walk into any upholstery supply store or fabric shop and buy latex foam anymore. I guess it's just too expensive for the masses.
I got mine from foamsource.com (link to the exact page below). I got medium firm for the seat and soft for the back--3" thick on each for the particular chair that I did. I tried urethane foam on it first and that was comfortable but the latex foam was just---I dunno, heavenly? It was SO nice. It was a Knoll chair with latex as the original foam, so I felt justified going for the extra cost. Very much worth it.
You might want to see if they will cut it to shape, though. And then your upholsterer will need to make rounded edges, but it looks like he knows how to do that so no problem there.
One other thing--Foamsource.com only sells foam in 1" increments of thickness. I don't know what the Womb chair thicknesses are supposed to be---did anyone figure it out upthread? If it's 2.5" or something, then the extra height can be added with batting. That's probably necessary anyway, since fabric directly on foam will grip the foam and cause creasing when you slide across it even a little bit. (The fabric slides with you, then the foam grips it in its new position and holds it there. Batting doesn't grip. But your upholsterer will know this, too.)
http://www.foamsource.com/shop/customize/

Thanks again Spanky
Very, VERY helpful. I'm definitely considering the latex foam.
I think from this thread it seems like the womb cushions are supposed to be about 4" thick (at the center) - so I wonder if it would be best to order 4" thick foam and shave it? Or 3" thick foam and add one inch of batting?
There's an expensive, larger-scale (and upscale) upholstery place very local to me ("Classic Design") - I might ask if they have examples or samples (and if they're helpful I would repay them for the research with my business, we'll see). It would save me a trip to San Diego as I'm in the LA area.
http://www.classicdesignla.com/

I'd do 4" thick latex foam...
I'd do 4" thick latex foam and have them add very thin batting that won't increase the thickness by any noticeable amount. It's barely batting at all, more like a fluffy, lightweight felt--maybe 1/4" thick at best. It should be glued directly to the foam and notched at the corners so that there's no lumpy bulk anywhere.