In order to encourage the reuse of glass containers, an ever increasing percentage of glass bottles are returnable on the North EU market. The bottler deals with the washing of bottles, filling, labelling & storage. The bottles are then put back into the distribution circuit for a new cycle of use. Since the glass which forms the bottles is a brittle material, its high mechanical resistance is weakened by the presence of defects, which seldom occur in the mass of the glass but are frequently found on its surface. It is therefore of prime importance to protect or strengthen the surface of the glass with one or more films composed of metal oxides or organic molecules. Despite the presence of such treatments, the surface of bottles can become scuffed after multiple use as a result of bottle handling & washing operations. These are mainly present at the different friction points of bottles when they knock against each other, on conveyor belts for example. Glassmakers & bottlers call these marks "scuffing." They alter not only the mechanical resistance of the glass but especially its transparency & its visual attractiveness. This article aims at developing a measuring method & apparatus to quantify scuffing. The interest of such a method is based on the following advantages: The possibility of defining a tolerable scuffing threshold; having a means to determine the rate of scuffing generated by a bottling line; being able to adjust & control the effectiveness of new means aimed at fighting the phenomenon of scuffing.
