foil, alternative name for the capsule which covers the cork and neck of a wine bottle. The term is most commonly used for bottles of sparkling wine because in this case it is almost invariably made of metal foil, whereas the ‘foil’ covering tops of bottles of still wine may be made from a wide range of materials. Traditionally lead or lead alloys were used to manufacture foils, but in Europe these were found to be a major source of soil contamination in disposal sites, and lead contamination of wine was traced to this source, so the use of lead foils has been phased out, and was prohibited in the US and the eu in 1993. Older bottles with lead foils should be wiped carefully around the bottle-neck between pulling the cork and serving. Various plastics and tin are used, as is, increasingly, paper. Of the two most common types, one is made from polyvinyl chloride (PVC) with an aluminium top and is heat shrunk onto the bottle (alternatives made from more environmentally friendly polyethylene terephthalate (PET) are also available); the other is a polylaminate consisting of layers of polyethylene and aluminium which is spun into place. The foil is there largely for aesthetic reasons since the closure should provide an airtight seal and only a faulty one will allow any seepage of wine. Very occasionally, in the case of an oversight during bottling, a wine may be bottled with a foil but no cork; a tight foil has been observed to act as an effective bottle stopper in at least one case. The length and design of a foil is another purely aesthetic matter, although some clear identification on the top of the foil can be very useful in a cellar full of bottles on wine racks.
