Hi Kopo,
I'm not quite clear on what you are asking and many of your questions are preference issues where there is no "better or worse" but hopefully I can point you in the direction where some of your questions are discussed. In general though I would avoid using a "formula" to choose a mattress.
The most important information is in the
tutorial post here
and the links inside it. Most of the links in this post (and others as well) are included there.
Are there any post that detail out useful questions to ask for a specific mattress type.
I would focus on researching retailers more than mattresses at first so that you know you are dealing with a knowledgeable, experienced, and transparent retailer or manufacturer. Everything else follows after that.
This article
talks about some of the things I would look for and the questions I would ask.
For example:
General:
1. Specific material at each layer
I don't know any other way but to ask "can you show me the details of all the layers in your mattress?". The tutorial post includes links about what to look for and some of the minimum guidelines I would suggest once you have the information. The actual choice of material type is a personal preference.
2. Material density at each layer
Again ... the only way I know to find out is to ask "can you tell me the type and density of all the polyfoam or memory foam layers and the type and blend of any latex in this mattress?". #4 in the
guidelines here
has the minimum guidelines I would use for foam densities and there is also more information in
post #2 here
as well about the factors that can affect durability.
3. IDL rating
ILD is not important when you are testing locally or if you don't have specific reference points about how different ILD's feel in different materials and combinations. With careful and objective testing your body will tell you much more than any ILD information whether a mattress is a good match in terms of PPP (see
mattress firmness/comfort levels in post #2 here
). It's also not something that I would expect a local retailer or manufacturer to disclose (because they know it's not important and is usually a sign that a customer is focusing on specs that aren't particularly relevant) although some will.
4. Price
This is one part of each
person's personal value equation
(and arguably not the most important part) and would depend on what they are looking at and the specifics that are most important to each person. There is
some information here
relative to price and materials but this is so relative and there are so many variables involved in mattress pricing that at best this is only the most general of guidelines and certainly not any kind of "formula" to determine the "value" of a mattress (which is relative to the criteria or each person) or to follow too closely.
5. Mattress construction: Differential vs progressive
These are just concepts that are meant to illustrate some of the ways that a mattress can be made in different ways to create different "feels" and be suitable for different people. There is no specific line between a differential or progressive construction and it's not something that I would use as anything but some generic information to help you understand why different types of layering can feel and perform differently. It certainly wouldn't be something that I took into account when I was testing mattresses because your own personal testing will show you the end result of any mattress construction and how well it matches your specific needs and preferences and bypasses the need to understand the more technical or complex information (except the quality of the materials which are always important). Once again without personal reference points based on your own experience in testing many different combinations where you have identified the differences between two mattresses that use the same materials but have different designs, this type of information would have little practical meaning in most cases.
Latex:
1. Latex material
This article
and
post #6 here
are two of the articles or posts that talk about the different types of latex.
2. Where is latex sourced from.
This doesn't matter nearly as much as the type and blend of the latex. There are many manufacturers who legitimately don't wish to disclose their wholesale suppliers for competitive reasons and it really makes little difference.
Interspring:
1. Spring type: Pocket coils, Offset coils, Bonnell coils, or Continuous coils
There is more information about innersprings in
this article
and
post #10 here
.
2. Spring material, tensile strength, guage?
Once again your personal testing will tell you whether a specific innerspring in combination with the other materials and components in a mattress are suitable for you in terms of PPP. Innersprings are not normally the weak link of a mattress. There is too much information that isn't available about springs for someone that hadn't studied and worked with them for years to make any meaningful assessments about them and I would stick to the basics which is the type of spring, the coil count, and the number of springs (although there are many other specs that can make a difference) but even this is secondary to your own personal testing and not a meaningful way to evaluate the "quality" of a spring or the suitability of a mattress. While it's also not a particularly accurate way to assess a spring ... the weight of an innerspring and the amount of steel it contains is probably the most relevant "quality" spec but this information isn't usually available.
A list like this would accomplish a number of things IMO, like save the mattress buyer time, save the expert time, allow meaningful comparison between shops, avoid missing critical questions.
IMO ... focusing on too much technical information can lead to information overload and "paralysis by analysis" and can become so frustrating that it leads to mattress choices based on specs instead of personal experience which can lead to just as many unsuitable choices as too little information.
It would also be awesome if the importance of each question could be rank ordered as well as typical response to each question and the response impact. This might be asking a lot, but would obviously be an extremely helpful resource.
The most important part of a mattress purchase can only be known with your personal testing or experience which is PPP.
The next most important part of a mattress purchase is knowing the type and quality of all the materials and components in a mattress and the minimum information I would look for is the thickness and density of any polyfoam or memory foam in a mattress and the type and blend of any latex.
If you have tested a mattress and it's a good match in terms of PPP, you know that the foam densities are relatively durable and good quality and there are no weak links in the mattress, and you have compared your "finalists" to each other based on all the criteria of your personal value equation that are important to you, then the odds are very high that you will make the best possible choice out of the mattresses that are available to you either in your area or online (for those that are comfortable making an online purchase).
Phoenix