An innovative barrier coating technology that will provide invisibility to the coating but at the same time not result in reduced clarity of the PET container, called Plasmax, has been developed by SIG. Plasmax is a cutting-edge technology for coating PET bottles, wherein, a pulsed, cold-plasma process deposits a thin-layer of glass-like silicon oxide on the interior of a PET bottle. The process occurs in a vacuum chamber, where the bottles are held neck down. A lance inserted into the evacuated bottle fills it with gaseous hexamethyl disiloxane. Microwaves are then generated to decompose the gaseous precursor, resulting in a deposit of SiOx on the bottle. Carbon dioxide and water, the two by-products, are removed by the vacuum system. This is described as a pulsed plasma system, in which changing certain process variables alters the plasma gas from one with adhesive qualities to one with barrier qualities. PET bottles are lined with a glass layer with a thickness between 0.01 and 0.1 micrometers. This barely perceptible layer of glass, applied by plasma, forms a barrier against oxygen ingress and carbonation loss from the bottle. This shielding effect increases the shelf life of products filled in PET bottles. Despite having a minimal net weight, the coated plastics bottles are provided with the properties of their glass counterparts. The internal barrier coating prevents the ingress of oxygen. In the case of carbonated soft drinks and beer it also prevents the outward migration of CO2. This benefit maintains the appearance and taste of the filled product and ensures a significantly longer shelf life than that of the currently widespread PET bottles without barrier protection. As the quantities of silicon oxide deployed are extremely minor; no visible changes are evident and the bottle can be recycled as easily as any other PET bottle. Plastic bottles from the Plasmax process are crystal clear and the Plasmax technology is highly economical. The total cost of producing barrier PET container is lower than with comparable barrier technologies.

Beer is a very sensitive beverage with a high level of carbon dioxide. Leakage due to porous packaging leads to ‘flatness', and taste distortion occurs if oxygen seeps in. Since PET is more porous than glass or aluminium, beer filled in standard PET bottles will have very limited shelf life. Beverages currently filled in glass bottles and cans represent enormous global potential for PET bottles. Hence the packaging industry and its suppliers have been working intensively for many years to improve the barrier properties of PET bottles. A six-month long series of storage and quality tests carried out by the Berlin-based brewing institute VLB (Versuchs- und Lehranstalt für Brauerei) has established that PET bottles treated using SIG's Plasmax barrier coating technology match the performance of glass. The trials, which included quantitative oxygen ingress and carbonation loss measurements as well as qualitative assessment of small, flavour and freshness, established that the Plasmax system meets the brewing industries packaging requirements in terms of product protection and quality. These results have transformed the PLASMAX coated plastic bottle into a viable alternative for beer packaging to the traditional glass bottle.

Amcor has offered barrier PET solutions for beer for the past six years. Its AmGuard bottles range for beer incorporates the company's pioneering Bind-Ox technology to provide shelf life of nine months and more for the product. Whereas normal barrier technology impedes oxygen entry, Bind-Ox technology is said to trap the oxygen and bind it into the bottle wall, thus preventing it from reaching the beer. Tests on this technology have shown that even after 12 months, the bottle continues to prevent oxygen ingress.