Best combo poly/latex for a 4" thick cushion/mattress to be used full time on a boat- no memory foam

[phoenix]

Hi Danibug,

As you probably know … I don’t recommend FBM for any purchase where getting what you think you’ve ordered is important or “application critical”. I don’t believe they even have any 20 ILD latex. You can read more or my thoughts about them in post #2 here and post #2 here. “Cheap” and good value are not the same thing IMO. Lots of things are cheap but there are not nearly as many that are good value.

Your design seems to be very firm to me and while it may be good for sitting … I would think it would be very firm for sleeping.

(What should a queen size 3" HD-36 HQ weigh so I can make sure they sent the right quality?) Would it be wise to use Dacron batten on top of the latex or would that defeat the purpose?

If you multiply the height x width x thickness in inches and then divide by 1728 you will have the cubic feet. multiply that by the density in lbs and you will have what it should weigh. I would also bear in mind that there are many cheap filled foams that have a higher filled density (vs the unfilled polymer density that determines the quality of the foam) but are still conventional foam and not the higher performing HR foam. If there is too much filler it will reduce the durability of the foam.

The dacron batting would be a matter of personal preference but it may add a touch of softness or “hand feel” to what would otherwise be a very firm mattress and it can help a material keep its shape with stretching. An inch of latex is not really significant and most of what you feel from this mattress would be the polyfoam. I personally would tend to use either a single layer of HR polyfoam (that really was HR) or a single layer of latex.

From reading online I know the HD-36 HQ can be pretty firm, but I’m thinking if I cut it to 3" it will soften up a little. I also know the 1" Latex won’t matter much for sitting, but when laying down it may make the area a little softer and cooler as we live and will be in HOT locations! I am however afraid the above arrangement will be too soft for sitting.

Thinner layers are actually firmer rather than softer because they compress to their maximum and bottom out much more easily. I believe this is the same “rationale” that FBM uses when they “rate” their softer latex and it certainly isn’t what happens with thinner layers. I would strongly suggest talking with a professional foam supplier that can give you much better advise for your specific application than FBM.

I don’t think it will be too soft for sitting (although the lower quality foam will have a lower compression modulus which may make a difference and it may bottom out more easily unless it really is HR foam). My concern would be more that it would be too firm for sleeping.

NO memory foam and we can’t go more than 4 inches as thats what our covers will hold. I’ve had it before and it’s HOT! We are both side sleepers pretty much, my husband is 230 lbs and i’m 130 lbs. He likes a softer sleep to a firmer sleep. We currently have 4" foam that seems high quality and keeps its shape but bottoms out when you sit on it. I am also open to modifying this foam if you think 1" or 2" of a different foam in combo with our older foam would help.

I will leave the specific design and layering to your discussions with your supplier because of the variables involved and they will be more knowledgeable about the specifics of the foams they supply but I would suggest that HR polyfoam or Dunlop latex … both of which have a much higher compression modulus (which is more important than ILD in your application and in furniture seating as well) … would be more suitable. I would choose a single layer of either if I was in your shoes.

Again though … I would not deal with FBM and I certainly wouldn’t speculate about what layering to use with their products when you have no real assurance that what they advertise is even what they sell.

This article along with this article and this article (all of which talk about polyurethane, support factor, and various other specs in terms of furniture design) may be helpful as well.

Phoenix