Flexible batteries can be made by printing onto plastic, thin metal foil, or paper. Tin foil is stiffer than aluminium foil. Hershey's KISSES chocolates are wrapped in squares of lightweight aluminum foil. Each film is covered with a thin metal foil, mostly aluminium, to form the electrodes. Sometimes these are wrapped with edible silver foil (vark). The nonconductive boards support layers of copper foil conductors. On this thin gold foil is pasted. The cable is encased for its entire length in foil or wire mesh. The process consists of imprinting a metallic foil with an image. There is still no silver foil used. This is usually achieved by small perforations in the radiant barrier foil. This was initially based on fluorine gas confined inside a chromium foil film. Bunsen serves as a foil for Beaker. The Americans won a single medal, the bronze in the team foil. This effect can be explained by the flow over an air foil.