PS foam is typically closed-cell because open-celled foams are brittle.

PS foam is typically closed-cell because open-celled foams are brittle. But Commodore Machine Co. in Bloomfield, N.Y., has developed an extrusion process and an application for open-celled PS foam sheet. Commodore developed the foam for a novel meat tray (U.S. Patent # 669519881, May 2004) called the A Tray, commercialized last year by Bunzl in St Louis, Mo. The A Tray uses a traditional closed-cell PS tray that supports an open-celled PS foam pad, which absorbs meat juices. The pad has a solid upper surface, so it doesn’t dry the meat out.