Biscuit tin moulds, 1937-1990.
© Science Museum / Science & Society Picture Library
Moulds for small tin lids made by Carnaud Metalbox. 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.