Since 1995 Coca-Cola in Uruguay has marketed its Bonaqua brand table water in a 1.5-L refillable bottle made of homopolymer polyethylene naphthalate (see Packaging World July '95 p. 26). Now Coca-Cola GmbH the German division of Atlanta-based The Coca-Cola Co. has developed a close cousin of that bottle for the German market. "Naturally our experience with PEN in Uruguay was channeled into the development of this PEN bottle for Germany" says Sven Erler manager of operations support at the Coca-Cola division's headquarters in Essen. "But this is quite a different bottle." While the bottle used in Uruguay holds 1.5 L Germany's bottle is an even 1 L. Also different is the liquid inside the containers. In Uruguay it's Bonaqua a "table water" that like other table waters in Germany is treated and/or enhanced with additional minerals. In Germany refillable PEN (REFPEN) is used for Minaqua a "mineral water" that comes from a natural spring and has virtually no treatment other than carbonation. Until the REFPEN bottle was developed Minaqua mineral water in Germany was not available in a refillable plastic bottle. It was sold in one-way 0.33-L cans and refillable glass in single-serve sizes. Table water Bonaqua however was marketed in Germany in a refillable bottle made of polyethylene terephthalate (REFPET). Why was table water sold in REFPET but not mineral water? Because the REFPET bottles used by Coca-Cola in Germany can only withstand wash temperatures as high as 59°C (138°F). In launching Minaqua mineral water in a larger package Coca-Cola wanted a bottle that could be washed at higher temperatures so that perhaps the amount of caustic solution used or the length of time required in the wash cycle might be reduced. As Erler puts it "PEN is a logical evolution from PET. It's more inert more glass-like. It made sense to use this new-generation resin as we moved Minaqua into a larger package." Because PEN can withstand temperatures considerably higher than PET Coca-Cola Germany's new 63-g container for Minaqua is washed at 80°C (176°F) instead of the 59°C mark that is the maximum allowable for the 80-g REFPET bottle. The hotter temperature optimizes the washing process. Erler says other performance characteristics of the new bottle are also impressive including its appearance and its performance in drop impact tests. The most notable feature of PEN however won't come into play. This is PEN's gas barrier property typically five times greater than PET. According to Erler Coca-Cola Germany codes its REFPET bottles of Bonaqua with a six-month shelf life and the REFPEN bottles will be treated the same. "There's no marketplace need for anything longer" says Erler.