Biscuit tin with lid, 1937-1990.
© Science Museum / Science & Society Picture Library
The lids of small tins are made from tin plated sheets of steel which are presed into shape. As the metal is so thin a machine using a force of about twelve tonnes can bend and stamp out the shape of the lid using a mould without the need to heat the metal. Before stamping, the sheets of tin plated steel are printed on one side with the pattern and varnished on the other. The varnish protects the tin and gives it an attractive gold colour. Made by Carnaud Metalbox.