latex is mixed with stabilizer and other ingredients, either as dispersions or emulsions depending on solubility in water. The compound is gently stirred and allowed to mix. Fillers may be added at this point. The compound may be left to mature for 24 hours. Through decomposition of hydrogen peroxide by yeast, bubbles are created which cause the foaming of the compound inside of the specialized mold. A vacuum is applied to the mold to promote expansion. The compound is then quickly frozen to create air bubbles. Finally, the compound is allowed to cure and removed from the mold. The disuse of a gelling agent in preference for carbon dioxide makes the process more environmentally friendly, but the Talalay process is still not widely used for specialized latex foams industrially. Properties Expansion and density In general, latex foams have lower density than the original polymer they are made of. This density can be measured regularly by taking a volume and mass measurement of the material. For a volume measurement of irregularly shaped foam, the foam pieces can be coated with wax and inserted in a known volume of water to measure volume change in the container. The purpose of the wax is to prevent water permeation into the foam, which may lead to a lower perceived volume (and higher perceived density as a result) if not accounted for. The density of a foam decreases as the expansion of the foam increases. Expansion, in turn, relates to the amount of air inside the cells of the foam. The more air inside the cells, the larger the expansion. Compression Latex foams demonstrate a stress-strain curve with three regions when compressed. This relates to the resistive force expressed by the foam when a load or force is applied to it. The shape of different regions of the curve will reflect some important quality of the foam relating to compression or relaxation stress and strain behaviour of the material. First, the foam will show a linear Hookian increase in stress. This happens because the gas contained in foam cells is compressed, and the walls of the cells maintain their structure. In the second region, the cell walls are being crushed, and no additional stress is experienced, and so the stress plateaus. In the third region, the foam increases in density as crushed cell wall material is compressed into itself. This leads to a steep increase