The initiative, called bright steel technology, looked at how brightness, colour and gloss measurements, using the latest DIISS technologies (Diffused Illumination Integrating Sphere System), could be improved. In addition, the steel producers established a common action plan to avoid duplication of their efforts and to obtain complete information on the manufacturing processes in operation throughout Europe in the shortest possible time.
Metallic gold and silver designs in packaging represent a high value image and are used frequently today in packaging concepts for 'high-end products such as single malt whiskeys. This value-added image is a key means by which a company can differentiate their products through packaging.
The task force attempted to improve metallic performance in packaging by analysing line configurations and establishing the parameters that critically influence the surface aspect of steel cans. In this way, the task force was able to identify the procedures required to optimise manufacturing in order to improve metallic appearance.
The surface brightness of steel was defined as the 'L-value' and the deciding factors such as material properties, tin weight, and surface topography were studied. Data concerning the surface development during the DWI manufacturing process, chemical washer treatments and thermal shock were collated and their correlation established.
Of course, can manufacturing plant configurations differ depending on when and where they were assembled, the technology used, and the local availability of materials and equipment. Each case needs to be considered independently and tailor-made solutions proposed for each individual production line.
Three critical elements during the manufacturing process were identified by the team as having a significant impact on appearance in the majority of line configurations. Firstly, the body maker, which depending on the number of rings (ironing dies) and the distance between rings creates a positive or negative surface effect. Secondly, the formation of oxides and the composition of the tin alloy layer, are seriously affected by operating oven temperatures in excess of 200°C.
Finally, the composition of chemicals used to remove die lubricants and for the surface treatment of steel which ensures optimum adhesion of protective coatings.
Leading can manufacturing locations in Europe are now implementing the specific profiles recommended by the team to optimise the surface appearance of their production and offer original transparent label designs of premium quality. Véronique Curulla, Crown Cork marketing executive for Bevcan Europe and Middle East, stressed that with the trend towards clear metallic designs, this technology has helped enhance the steel can's visual appearance and optimise shelf appeal.
"We are currently using this bright steel technology in our Seville and Custines plants, and bright steel is used in Spain by Coca-Cola for approximately 20 per cent of their volume," she said. "Furthermore, we have recently successfully produced a bright steel design for the Brasseries Fisher brand 'Doreleï', one of the leading brewers in France."
The choice of a transparent metallic design for 'Coca-Cola Light' on steel further underlines the fact that manufacturers are increasingly seeing the metallic brightness of steel as a means of achieving added value for consumer.