Hi klphot7,
It will depend to some degree on the “type” of firmness you are talking about because there are different types of firmness and softness that each come from different layers in a mattress (see post #15 here). It’s much easier to soften a mattress that is too firm than to firm up a mattress that is too soft and “unsupportive” because a firmer topper will generally “bend into” any softer layers that are underneath it or “follow” any soft spots or sagging in the mattress so the effects of a firmer topper will tend to be limited or temporary. In most cases making a mattress that is too soft any firmer would require removing and replacing the upper layers that are either too thick or too soft although a firmer topper can affect the “feel” of the sleeping surface.
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to each other and to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may be helpful in clarifying the different types of “support” and “pressure relief”.
There are also some suggestions in post #4 here that may be helpful as well.
[quote]A link to this discontinued mattress that really doesn’t give many specifics of the foam etc (lovely PR description that makes it sound it was designed in heaven itself lol) www.searsoutlet.com/Perfect-Sleeper-%231...id=81240&mode=seeAll
In the worst case scenario Im back where I started and can use this in a guest room with no financial loss.[/quote]
You’re right that the description doesn’t provide any specifics but the information they do provide certainly indicates that there are enough lower quality materials in the comfort layers that will be subject to foam softening and sagging that it would be a weak link in the mattress (like most major brand mattresses). Having said that … it’s tough to argue with “free” and if it’s a good “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) then any amount of time that you sleep well on it would be a “bonus”.
Phoenix