Latex is a spongy material, with pressure relieving properties, much like a memory foam. The difference is that it has a much faster reaction time, making it somewhat more desirable and used in premium mattresses. Latex is produced in two ways: naturally from a rubber tree plant, or synthetically. There are two types of latex — Talalay and Dunlop. The first, talalay, has a uniform density and broad range of softness options. Liquid latex is whipped with air until it becomes wet foam, at which time it is poured into a mold, leaving room at the top. Once the mold is sealed, air is vacuumed out of the mold, causing latex particles to fan out evenly to all corners of the three-dimensional space inside the mold. The result is uniform particle density of the foam. The second, Dunlop, has a higher density with “progressive” compression characteristics. This is the result of not being vacuum-sealed, and thus the heaviest particles sink to the bottom. This is less costly and used mostly as a support layer, rather than a comfort layer.