Reducing CO2 Permeation Test Times For Bottle Manufacturers

By Tim Ascheman

Plastic beverage bottles do a near-perfect job of holding their liquid contents. The real challenge is holding CO₂ gas, which can travel through the bottle wall, the cap, or the seal where cap and bottle meet. Because carbonation life is critical to the shelf-life of the product, the rate of CO₂-loss is of interest to both bottle manufacturers and bottlers.

Until now, the methods of testing a container’s ability to retain CO₂ have been destructive Zahm-Nagle testing or Carbo QC pressure testing, and Fourier Transform infrared (FTIR) testing, which uses light to measure the amount of carbonation remaining in the liquid after a period of time. Unfortunately, these methods are labor intensive, require a great deal of product, and take weeks or months to provide useful predictive information on rates of CO₂ loss.

There is, however, an effective, non-destructive way of determining, in just hours after a bottle has been conditioned, the amount of CO₂ permeating out of a bottle and the expected shelf-life of its contents. This method is less expensive, far faster than other testing methods and equally accurate. And it can be used for speedy determination of the amount of CO₂ loss through the bottle wall, the closure, and across the seal.