Phoenix,
Firstly, your site and forum (and posts) are outstanding. Thank you for creating and maintaining this site. It is invaluable!!! We have learned a lot here.
Our current mattress is an S&F Kensington King (about 15 years old). We considered purchasing a new equivalent high quality mattress but the prices are literally out of this world ($2k-8K). We are also very concerned about chemicals used too (poly itself, then fire retardants, etc. We started seeing depressions in our S&F at about 5 years but no real support issues until now.
Our S&F is made extremely well in my opinion. It is double sided w/ wool pillow top. We kept it like new and always flipped it regularly. The materials used in construction (fabric, springs, sewing, etc.) are very good. However, things fail over time and we understand that. We are not over weight (165 and 140 lbs each).
So we decided to open it up and found the upper layers of poly foam (2" worth) has failed. I put a level on the springs and laid on them and they seem fine (heavy gauge coil design too.
When new the, S&F perform flawlessly, My wife would not even notice me getting in bed (very good isolation). Firmness was perfect too.
In summary, we wish to replace the failed 2" foam/polyester with something better like Talalay 2" N4 topper foam. I have a sample of the Talalay and it seems very soft and then to have 1-2" of wool pillow top makes me think it will be too soft and not acceptable. We prefer a medium-firm mattress with a soft top. I know there is no rule of thumb for customizing/building your own mattress. We just want to get the “original” back feel out of our S&F.
Attached are some pics of the labels, layers (1.5") and the polyester (1") that sits on top of spring. Layer order is: coil spring, 1" polyester, 1.5" poly foam, 1-2" wool pillow top.
Thoughts on what to use and at what ILD or density? We prefer natural products. My concern is that the density (and ILD) and feel of the different foams vary greatly, especially when layered. I am confused and don’t want to make a big mistake by ordering the wrong Talalay ILD.
https://uploads.mattressunderground.com/outside/37166/S&F_Lable1.jpg
https://uploads.mattressunderground.com/outside/37166/S&F_Lable2.jpg
https://uploads.mattressunderground.com/outside/37166/S&F_Lable3.jpg
https://uploads.mattressunderground.com/outside/37166/S&F_Sag.jpg