Today’s tinplate trade covers both the manufacture of tinplate from steel and the conversion of this into metal packaging, widely used for food and beverage cans and other products. Tin coating on thinly rolled sheet steel provides resistance to corrosion. It is used both to protect food, beverage or other products contained in the package (the ‘can’ or ‘tin’) and to resist external factors such as heat processing steam/water systems. A polymer coating is sometimes added on the inside surface, to prevent chemical action and the possible transfer of taint between metal and product.
Historically, tinplate has been commercially made in the UK since the late 1600s, originally by dipping sheets of wrought iron, and later steel, into baths of molten tin. During World War II, electro-coating (or electro-plating) was introduced, allowing the continuous application of tin to both sides of the metal simultaneously; tin could thus be applied to wide coils of steel, which could be unwound, coated and then rewound. This, in turn, encouraged the concentration of manufacture onto fewer sites. A hundred years ago there were 83 tin plate works, mostly in South Wales. Today, there is a single UK manufacturer, Tata Packaging Steel at the Trostre factory in Llanelli, though many businesses make packaging products.
Tinplate products include processed food and drinks cans; aerosols; lug caps (for glass jars); crown caps (for drink bottles); and homecare, DIY (eg. paint), industrial, promotion and giftware containers. Tinplate is inherently stronger than aluminium, so it is used both for seamless thin wall cans and for cans made by rolling flat sheets and welding or folding a side seam. By contrast, aluminium is generally only used for containers that have internal pressure after filling, or where the strength of the side wall is not critical. Thus aluminium is used for seamless thin wall cans for beer and carbonated soft drinks; aerosols made by impact extrusion; seamless shallow fish (e.g. sardine) and other food cans; and most caps and closures other than those listed above for tin plate. In Europe, around 80% of seamless beverage cans are made from aluminium and 20% from tin plate.
Today, some 21 UK metal packaging businesses employ approximately 4,200 employees, in 35 factories, using around 665,000 tonnes of metal annually.
In Europe as a whole:
- there are around 450 manufacturing sites, with 65,000 employees;
- five million tonnes of metal makes over 85 billion metal packaging units every year;
- metal packaging comprises around 15% of the packaging industry, by turnover;
- 7% of metal packaging is recycled – more than for any other type of packaging.