Color measurement of plastics bottles and tops

The quality of packaging is an important element in the CPG (Consumer Packaged Goods) industry. For beverage companies it important to have high quality bottles and caps. To control quality many companies have tight specifications and controls on the color of their packaging. Measuring PET preform colors at different points to helps ensure the fully blown bottles meet a desired color.

Color measurement for bottles, caps and closures are done in stages; product development, in-coming inspection of raw materials, preform of bottles and the finished product for caps and closures. To get accurate measurement of color use an instrument like the bench top CM-5 spectrophotometer.

Tips for color measurements in different stages of the creation process:

• In-coming inspection of colored materials like masterbatch or resins use a glass cell or a petri dish to hold the pellets, ensuring repeatability of the measurement. Once filled up, use a cell or petri dish set on top of a bench top spectrophotometer like our CM-5, to take a reading. If the reading is out of the tolerance range, the material might be reworked or rejected.
• During the Preform Stage bottle color is measured. It is critical to obtain the right color in this stage before molding the preform into its final shape. The bottle preform is similar in shape to a cylinder you may find in a lab. Use a preform holder for consistent placement of your measurements. The Custom Preform Holder for the CM-5 is a helpful tool for transmission measurement of preforms.
• For caps and closures use the reflectance function of your spectrophotometer, we recommend the CM-700d Spectrophotmeter for this measurment. Although many measure the top of the cap alone, for reproducible data average the results of measures to the cap’s various sides in different positions and angles.

The Custom Preform Holder for the benchtop CM-5 spectrophotometer is a quick and reliable way to measure the color of a preform. This CM-5 accessory is perfect for companies in the beverage industry or any other plastic bottle manufacturing facilities.