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Foams & Latex: Lesson 7

A key factor is knowing what your bed is made of and how it’ll will wear, while developing a reasonable expectation of how long the bed will be comfortable, and what you need to do to maintain it as long as possible.

Foam is a critical component of your bed – you can wake up feeling like a million bucks on good foam, or a Dickensian pauper on failing foam. And in recent years, the buzzword of the day for mattresses is a well-marketed plastic foam that may seem easy on budget today, but not in the long-run and is worse on the environment than an all-natural plant-based rubber.

Plastic foams first. It is the most commonly used material in the industry. Cheap to produce and available in many variable feels and densities, these foams can be up to 20% plant based oils. They are also frequently referred to as soy foam, natural foam, or plant based foam; they are however, still 80% petroleum, and far from natural. They can be processed special and made into memory foam or viscoelastic foam, or gel foam.

In your standard poly foams the smell will usually dissipate within about a week to a point where it is not even noticeable. In the case of memory foams, where the chemical residue is on the inside and the outside, and there is much more exposed surface area, the smell is much more intense and will persist at noticeable levels for much longer.

During the 1920’s the Dunlop Tire Company developed a process to turn tree sap into a rubber foam. They took latex sap from a rubber tree, whipped with a soap and cooked in a glorified waffle iron; this was a petrochemical free process. Where is you whipped it more, you’d have a lighter softer foam, and whipping it less made for a hard and heavier foam.

However nowadays, rubber foams are not always pure natural tree rubber. Within the mattress industry, the use of synthetic or blended rubber (ie rubberized plastic) is far more common the use of actual tree rubber (due to factors like material and transportation costs and competitively low margins). This synthetic rubber will off-gas just like any other plastic foam. It also wears like a plastic foam.

Actual natural tree rubber latex is a very durable mattress component. With the Dunlop process of making foam, a 6” core will compress about 1/8 of an inch over a span of 20-30 years. This implies that there would be little to no change over a pretty long period of time, and though the lack of compression is great, the material will soften where it gets the most use.

Different processes for making latex foam lead to disparate qualities. Even within the dunlop, continuous pour, or the talalay processes, you will find wide discrepancies in quality. Some manufacturers take greater care in creating consistent cores, which helps the foam to stay supple and responsive.

One thought on “Lesson 7 – Foams & Latex

  1. Alice Carroll says:

    You made a good point that the thickness can give me an idea about the hardness when buying a mattress. I’d like to look for a mattress store soon because I will be having a new housemate soon. I’d be giving her my current mattress so I’d like to buy a new one for myself soon.

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