When choosing the mattress that best suits their needs—not only for rest but also for health—more and more people are opting for a latex mattress. We often hear about latex foam mattresses, but what exactly are they? And how do you choose the best product?
Polyurethane foam, viscoelastic polyurethane foam, and latex foam are the most commonly used foams in mattress production; in particular, polyurethane foams in Italy—including various “sandwich” combinations—account for about 95% of the latex foam mattress market. We have many compelling reasons for deciding that our product line should exclusively feature natural latex foam.
Kipli has chosen to offer only mattresses made entirely of natural latex foam because we know that this material is superior to polyurethane and viscoelastic polyurethane in many respects, even when combined.
Latex Foam
Latex foam is a foam made from liquid latex and solidified through vulcanization. The remarkable property of latex molecules (particularly natural latex versus synthetic) is that they are extraordinarily long (you can imagine the molecules as a plate of cooked spaghetti); vulcanization creates three-dimensional bonds between the “spaghetti” strands so that, when they are stretched during the subsequent release phase, they essentially and rapidly return to their previous shape (elastic property). The transformation requires the addition of sulfur and zinc oxide-based accelerators to the latex. The latex can be obtained by tapping the bark of the Hevea brasiliensis tree or through the polymerization reaction between styrene and butadiene to produce synthetic latex.
Kipli has chosen to manufacture its mattresses and pillows using exclusively and entirely natural latex for its products, completely eliminating synthetic materials.
Latex foam provides a precise response to every applied force and reacts instantly to every movement or change in pressure. This is the main difference between latex and memory foam mattresses, the latter of which are generally made from polyurethane foams.
Natural latex foam does not sink under pressure and, most importantly, does not collapse as the temperature rises due to prolonged contact with the body. Latex foam maintains constant support proportional to pressure without becoming softer due to heat. Its unique ability to conform proportionally to pressure—and to do so with precise responsiveness for each individual anatomical region—is a fundamental property for providing optimal comfort during sleep, particularly when sleeping on one’s side, where the pressure exerted by the shoulders and hips requires the mattress to deform significantly relative to its thickness.
Another difference between latex and memory foam mattresses is that latex foam is certainly one of the foams that offers the best durability and retains its initial elastic properties (Laboratory tests conducted in accordance with EN 1957 showed negligible losses in thickness and objective/subjective support both after 30,000 stress cycles—simulating the mattress’s useful life—and after 60,000 cycles; furthermore, the minimal variations are essentially attributable to the behavior of the cover/fabric).
Unlike other foams (including those derived from synthetic latex), this foam easily passes the most stringent tests for emissions of harmful substances (VOCs); in particular, the natural latex foam used by Kipli has been certified under the Oeko-Tex Standard 100, Class 1.
Polyurethane foams
Polyurethane foam (polyol + isocyanate) is certainly the cheapest and lowest-quality foam used to manufacture mattresses or mattress toppers. Consumers are familiar with polyurethane foam, which is commonly used in the seating of sofas and armchairs and comes in attractive colors, often in a “sandwich” configuration with layers of different characteristics for mattresses. Polyurethane foam is produced by the reaction between a polyol (generally of hydrocarbon origin) and an isocyanate (a substance whose hazards to workers are well-known and evident by simply Googling “isocyanate safety data sheet”). Polyurethane foams are also commonly used as layers applied on top of traditional or pocket-spring mattresses, thereby easily increasing their thickness and visual appeal at the point of purchase. Polyurethanes can have highly variable densities (and thus be more or less lightweight); the quality and cost of the product are generally proportional to its density; precisely because of their low density, polyurethane foams lend themselves more easily to compression and rolling, a method of packaging that obviously simplifies the entire logistics chain.
Polyurethane foam can provide some degree of targeted support for the human body’s anatomy; however, an analysis of how the most common polyurethanes behave under applied stress reveals a less linear response than that of natural latex, with a tendency to exhibit high resistance to low loads and then deform rapidly once a certain load threshold is exceeded.
Polyurethane foams rarely have certifications other than CertiPUR, which is a voluntary verification and monitoring program for the use of substances that are prohibited during production and hazardous to the product’s use; while this is an important step toward transparency and health and safety, it is clear that it lacks independence, as both the organization and its criteria were developed within the industry itself.
Memory foam / Viscoelastic polyurethane or shape-memory foam
It is a type of polyurethane that contains specific additives that modify its elastic behavior, causing the distinctive delay that allows one to see, for example, the shape of a hand resting on it for a few moments. Obviously, as with polyurethane, most of the components used to prepare the “visco” are derived directly from petroleum chemistry (polyol + isocyanate).
Generally, “visco” foam is denser and therefore more expensive than polyurethane foam. This type of foam is certainly better able to conform to the body’s contours than regular polyurethane; however, it differs from 100% natural foam in that it lacks performance in terms of support and load-bearing capacity (which is why it is usually used in a thin top layer of 2–3 cm), causing the phenomenon of progressive sinking—also due to the heat that eventually accumulates between the body and the compressed foam (even in the case of partially open-cell viscoelastic foam, the viscoelastic nature of the material causes the cells to close due to compression, making them impermeable to air and heat in a vicious cycle). In this regard, we suggest asking someone you know who has purchased a viscoelastic mattress or pillow and can describe the unpleasant experience of sinking in and progressive heat buildup, along with a lack of support. The loss of thickness in viscoelastic foam is progressive and increases with body heat; since, naturally, during a night’s sleep the body undergoes a series of major position changes (from lying on one’s back to lying on one’s side, for example), escaping from the “deep pit” of viscoelastic foam requires significant muscular effort in the absence of the material’s elastic rebound, which inevitably leads to a decline in sleep quality or even waking up.
Even the recent proposals to add gels or microcapsules (phase-changing materials) capable of absorbing heat to these foams are largely inadequate measures, since the amounts of heat that can be temporarily sequestered are orders of magnitude smaller than those actually at stake; not to mention that this simply adds more chemicals to the mix.
Kipli believes in natural latex mattresses and in the future
We stake our history and reputation entirely on natural latex. As described above, natural latex offers advantages in terms of performance, durability, and environmental sustainability (to produce a double mattress made of 100% natural latex, approximately 2,500 trees must be harvested in a single day, which corresponds to an area of about 40,000 m²). We know that no other material can provide all the qualities and performance benefits that natural latex offers while also helping to improve the environment in which we live. We care for ourselves and the planet we share!