Aluminium foil is widely used to seal yoghurt containers (e.g. plastic cups) and owing to the acidic nature of yoghurt and the necessity of heat sealing, the aluminium foil is normally coated with a layer of plastic. If the preformed type of plastic cup is used, the aluminium foil lids are usually precut and around 2500–3000 lids are packed into a special magazine to minimise mechanical damage. The diameter of these lids is <100 mm, and they usually have a pull-tab for easy opening.
The gauge of the foil is around 40 μm, and each lid is normally embossed. The embossing pattern can be varied to suit the customer's requirements and the impression can be up to 100 μm in depth. The embossing is essential to facilitate easy pickup of single lids from the magazine assembly prior to placing over the filled cup and heat sealing.
