I am often asked to define (or explain) what each method of latex pouring is: ie the Dunlap vs. Talalay methods, so I want to explore this option a little more for the Rocky Mountain Mattress Blog readers.
Latex comes in two different forms. Natural latex is composed of 95% natural rubber. Synthetic rubber is made of chemicals that are processed to form rubber. There are also two forms of latex pouring. The Dunlap method is more traditional and cost effective. The Talalay method provides the benefits of natural latex with chemicals.
Natural latex is a milky white liquid made of tiny rubber particles. The liquid is whipped with air. This whipping action forms the foam. The liquid is then formed into a mold where it is then heated. It is heated until it becomes a spring like rubber material. This method is fairly straight forward and is cheaper than the Talalay method.
The Talalay method requires more steps than the Dunlop method. It produces a more resilient form of latex and also a finer product. Soap and other curing products are mixed with raw latex. Computers are used during this process to check the temperature and viscosity of the mixture to ensure uniformity. Once the mixture is cooled, it is then whipped with air, similar to the Dunlop method. It is whipped until the consistency becomes similar to soft-serve vanilla ice cream. Then, the liquid is poured into molds. Iron rugs are moved up and down throughout the liquid while it hardens to form the open-cell structure.
The next step in the Talalay process requires a vacuum. The vacuum is used to remove air bubbles and make sure the mixture is spread evenly throughout the mold. Next, the latex is frozen. This prevents anything from settling at the bottom and ensures each particle is evenly mixed. Heat is used next to again make sure that no air is left in the foam. Then, the foam is taken out of the molds and washed at least five times. This removes any soap residue or other chemical agents. The foam is then dried. The final step is impact testing. Uneven pieces are removed and the final latex foam is cut into slabs and stored.
The Dunlop method of latex pouring uses natural latex. This method is a shorter process and is more inexpensive. The Talalay method combines natural latex and synthetic latex to create an open cell structure. This is a longer process and is more expensive. Both methods produce a good quality latex product that can then be used in latex mattresses.