Aluminium foil foil rolling mills to the desired thickness, or by continuously casting and cold rolling. To maintain a constant thickness in aluminium foil production, beta radiation is passed through the foil to a sensor on the other side. If the intensity becomes too high, then the rollers adjust, increasing the thickness. If the intensities become too low and the foil has become too thick, the rollers apply more pressure, causing the foil to be made thinner. The continuous casting method is much less energy intensive and has become the preferred process. For thicknesses below , two layers are usually put together
Tin Woodman iron or steel but coated with tin (in order to prevent rusting) is called a "Tin" object, as a "tin bath", a "tin toy", or a "tin can"; thus, the Tin Woodman might be interpreted (in English, at least) as being made of steel with a tin veneer. One passage in "The Road to Oz," by Baum himself, wherein the Woodman attends Ozma's birthday party accompanied by a Winkie band playing a song called "There's No Plate Like Tin," strongly implies that this is the case. Another explanation may be that the Woodman is "chiefly" made of tin, with iron