Foam logs, blocks, and insulation supplier in Arlington, Washington
Expanded polystyrene (EPS) is a very common product that is widely used for packaging and in building construction. Manufacturing of EPS blocks begins with expandable polystyrene resin beads that are generally less than 3 mm in diameter and contain microscopic cells filled with a blowing agent.

The usual blowing agents are pentanes or butanes and constitute about 5 percent of the bead weight. When exposed to steam under controlled pressure, the cell walls soften and the blowing agent expands. Individual resin beads enlarge by up to 40 times in volume to form pre-puffs.

After a holding period to allow stabilization at room temperature, the pre-puffs are poured to fill a rectangular molding box. All six sides of the mold are fixed and more steam is injected through small perforations along the confining walls. The pre-puff in the molding box further expands and fuse to form a block.

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