Understanding Different Types of Latex
Natural latex is harvested from the sap of rubber trees grown in specific regions of the world. Natural latex is not a perfect product by the very nature of its being natural. The sap harvested is affected by soil conditions, the amount of rain, and other factors that make one batch better than another. The degree of difference is not great but enough that makes it necessary for purchasers of the raw material to test for quality. It is much like buying coffee beans to arrive at different blends. Natural and synthetic rubbers have differing properties. Natural rubber is very soft and elastic, while synthetic rubber gives the foam stability and firmness and makes the processes used during production easier to work with. To obtain the best overall properties in the product and to stabilize prices, blends of natural and synthetic are used.
Before WW II virtually all latex used in production was natural. A search for the synthetic alternative began during WW II because supplies of latex from the Far East were very restricted. Scientists tried to copy natural latex (derived from cis-polyisoprene) and the result was inferior. They developed a latex based on a synthetic polymer that behaved in a similar way. The word “polymer” simply means a compound made up of long chains of molecules, each link in the chain being derived from simple chemicals known as “monomers”. A number of synthetic latices were developed, the most useful one being made by polymerizing Styrene (a liquid) with Butadiene (a gas) to give Styrene-Butadiene rubber, abbreviated to SBR.
CONCLUSION: Compounders of latex use a “BLEND” of synthetic latex mixed with natural latex for 3 reasons:
- Creates the most consistent product, ensuring consistency throughout the entire core.
- Allows for a greater range of firmnesses, anything from very soft to very firm.
- Keeps the price consistent, allowing for finished mattress products with stable prices
Manufacturers Use Blended Latex to Produce Better Products
The major mattress manufacturers found, early on, that they could not rely on the “less than perfect” natural latex if it varied from provider to provider. But the natural properties of latex were still needed to make a great mattress. To solve this they began using blended latex to produce a longer-lasting mattress.