Sun protection factor for glass bottles

Australian researchers have developed a transparent sunscreen coating for glass bottles that will prolong the shelf-life of medicines, beer or cosmetics by protecting them from deterioration by light.

Clear glass and some green bottles allow damaging wavelengths of ultraviolet and visible light, indigo and blue light to pass through them. This leaves products vulnerable to light-induced damage unless they are placed in an opaque amber or blue bottle that does not allow users to see how much is left inside.

The research team at CSIRO Manufacturing and Infrastructure Technology (CMIT) in Clayton, Victoria has developed a coating using particles with an average diameter of 30 nanometres. The visible spectrum of light is 400–700 nanometres. Bottled beverages, foods and medicines are damaged by wavelengths between 200nm, or near-ultraviolet, and 450nm, or blue light.

The CSIRO coating, made predominantly from iron oxides, can absorb the more energetic wavelengths that occur between near ultraviolet and green light (200–550nm). Harmless yellow and red light can still pass through the bottle. This gives the same protection as provided by blue and amber bottles, while allowing the consumer to see the contents.

‘The coating has been specifically developed to extend the sell-by life and freshness of liquids and foods in glass containers by removing the danger of solar-induced deterioration. Independent industry testing authorities have proved this in trials with beer and white wine,’ said Imre Lele, director of Australian company Bottle Magic, which developed the coating with the CSIRO.

The coating, which gives bottles a slightly green hue, is sprayed on as an anti-scuff scratch resistant layer. Other pigments may also be added without affecting the coating’s effectiveness. Bottle Magic is discussing commercialisation of the product with multinational beverage companies, with a view to launching it in Europe or the US.