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DIY latex mattress help ( budget )
additional comment: I also don't want the middle layer of talalay to be so close to the ILD of the 4 inch 35 ILD base foam that the base foam serves little purpose, if that makes any sense. Would 28-32 natural talalay (Radium) be just as firm as 35 ILD base foam. I know these questions may be impossible to answer due to all manufacturing processing and formulas of foam being different, but maybe a rough guess would be ok.
If I went with the medium 24-27 I would have somewhat of a safeguard, as I could use it over the soft as a top layer. However if I went with medium firm 28-32 and it was TOO firm, it most life would make a poor top layer given my affinity for a soft top layer. The only way to soften it would be adding a 1.5 inch topper of some sort. So many variables to consider...
You are correct that there is no way for me to predict what you may or may not like for your new “transition” layer, due the many variances and subjective nature of selecting comfort layers.
I would avoid attempting to get too detailed in using empirical numbers in attempting to predict what a mattress "might" feel like, as unless you are very experienced with mattress design and how different materials interact (which would be very few people), attempting to get too technical only serves to drive you further down the rabbit hole into paralysis analysis. I hesitant to provide too much extra information, as I’m fearful of contributing to this and thus not being helpful to you, but I do understand your desire to learn, and you do have a reference already of some combinations.
With that in mind, here’s how ILDs are measured and how polyfoam and latex ILDs are not directly relatable. In addition to this though, ILD is not the most reliable indicator of how soft or firm a layer will feel. Compression modulus is even more important because very few people actually sink into a layer exactly 25% and compression modulus is the rate at which a foam gets firmer as you compress it more. Latex has a higher compression modulus than polyfoam. Also, latex is very "point elastic" which means that a smaller area can compress with less effect on or resistance from the surrounding area than polyfoam. This is much like the difference between pocket coils that act individually and innersprings that have helicals that join the springs together so that the compression of each spring will affect the springs around it which makes the spring stiffer. Latex also has a lower hysteresis (how much energy is absorbed) and conversely a higher resilience (how much energy it returns) than polyfoam so there are also factors that can make latex feel firmer depending on how much a specific layer is compressed in a mattress. Because of its unique qualities and ability to take on the shape of the person on it (point elasticity) it can feel softer and firmer at the same time and some will feel it as one or the other depending on what they are more sensitive to, their body type, sleeping position, and how they sink into the mattress.
Overall, I would tend to take step back and look at the big picture a bit. You’ve decided you like Talalay over Dunlop. If the 19 ILD Talalay on the polyfoam core felt good but you desired a bit more plushness, then with your size the 24-27 could be a good choice. If you were “feeling through” the plush Talalay to the core, then the firmer Talalay at 28-32 would probably be a good choice, but I don’t think this is what you’re describing (that combination would tend to result in a bit more “mediumish” to “medium-firm” feel).
That’s about as “boiled down” I can phrase it without getting into the weeds too much. I hope that helps you as you go through your decision-making process.
Thank you Phoenix, I appreciate the thoughts here. I did read that post about ILD's, very interesting. Let me ask this if I may; in your estimation would a 23-27 "medium" Radium talalay layer, be very close to a soft 20 from SOL? If it has close to the same amount of "sink" when the two are paired in the final configuration, it may be too much sink for me. I thought I read in some of your posts that a soft dunlop is comparable to a talalay of 5 ILD points ahead of it. Maybe I am mistaken about this, if so I apologize.
My fear I suppose, is that the 19-22 radium talalay I have now, paired with the 23-27 medium that 247 mattresses is providing, is going to fall on the number 23. If my soft happened to land on 22, then there we have two layers with one point separating them, and I am stuck with 2 softs essentially. This is my dilemma. I don't want to have to send another layer back, but I also don't want to get the 28-32 and it's as firm as my existing poly base foam. To be certain I need more give than my base foam provides. I suppose this is the risk in DIY.
I talked to the seller about this as well, and while they assure the medium will be firmer than the soft, there is no guarantee it will be firm enough. Ditto if I go for medium-firm, could be as unforgiving as my existing 19-22 soft talalay- 35 poly base.
I am just talking out loud here.
Let me ask this if I may; in your estimation would a 23-27 "medium" Radium talalay layer, be very close to a soft 20 from SOL?
You should notice that it would feel slightly firmer, and also there will be more of a difference as I think you said you are going from a 2” layer to a 3” layer. Also, remember that a smaller ILD difference will be more noticeable between plush layers (lower ILDs) than firmer layers (firmer ILDs), as it will be a larger percentage difference.
If it has close to the same amount of "sink" when the two are paired in the final configuration, it may be too much sink for me. I thought I read in some of your posts that a soft dunlop is comparable to a talalay of 5 ILD points ahead of it.
Don't try to be too predictive with specifics in an area where there is no such thing. All ILDs are within ranges, and the overall comfort depends upon how all of the layers of the mattress work together . Only your own personal testing of configurations will determine if the layers work well for you, which is part of the overall DIY process.
My fear I suppose, is that the 19-22 radium talalay I have now, paired with the 23-27 medium that 247 mattresses is providing, is going to fall on the number 23. If my soft happened to land on 22, then there we have two layers with one point separating them, and I am stuck with 2 softs essentially. This is my dilemma.
ILDs don’t work in this manner and are not something where you add up and divide or come up with averages. This is why many manufactures choose to describe the foam layers as “soft” or “medium”, as it eliminates the temptation of consumers to come up with exact specifications in a situation where none exist.
What this means in "real life" is that trying to predict how a mattress will feel and perform using only one of many "specs" or variables that are involved can be somewhat risky or misleading, and even the most experienced mattress designers that are familiar with and have a great deal of experience with all the many variables and specs that can affect the feel and performance of a mattress can often be surprised at what a mattress was "supposed" to feel like based on specs and what it "actually" feels like in real life so in practical terms the only reliable way to know how any specific combination of materials and specs will feel like for you would be based on your own actual testing or personal experience. Specs can be a very rough guideline that can help you "find the range" but there are far too many unknowns and variables to use them to find the "best" combination or materials or components that would be suitable for any specific person with any degree of certainty.
I don't want to have to send another layer back, but I also don't want to get the 28-32 and it's as firm as my existing poly base foam. To be certain I need more give than my base foam provides. I suppose this is the risk in DIY.
I understand wanting to get everything right on the first or second attempt, but that’s all part of the experimentation and fun of a DIY project.
Phoenix, I wanted to thank you again for all your assistance, it has been greatly appreciated. It's true that I want to make as few of mistakes as possible, however I suppose the mistakes are the teachers in the long haul. I went with the 28 for the middle layer, here's hoping!
You're very welcome, and I'm looking forward to learning about your new arrangement!
In anticipation of my eventual configuration and the desire to protect the latex layers for as long as possible but also feel the latex doing its magic, do you think this cover would protect it from the forces which seek to destroy it? Or would you go also put an allerzip waterproof mattress encasement over that? Maybe that is overkill, I don't know. To me just the mattress cover with stretch to it seemed ideal and I would avoid the mattress encasement and just use a waterproof pad on the top. Any suggestions would be appreciated.