How to Solve Pearlescence and Haze Challenges in Blow Molded Bottles

How to manage unwanted coloring in blow molded bottles

How to Solve Pearlescence and Haze Challenges in Blow Molded Bottles

When manufacturing blow molded bottles intended for food and beverage, industrial chemical and personal care markets, issues managing pearlescence and haze can lead to costly delays and disruptions – including unwanted downtime, higher scrap rates and quality concerns.  

Pearlescence, also known as stress whitening, causes a milky coating in the bottle and is often caused because the production temperature is too cold.  

Haze, thermally induced crystallization on the exterior of the bottle, is often caused because of overheating.  

Common causes of pearlesence and haze occur during processing.  

Questions to ask before and during production include:  

  • Is it hot enough to get the clarity you are trying to achieve?  
  • Is there enough moisture, or perhaps too much moisture content?  
  • Is the temperature setting correct?  

To prevent pearlescence and haze, consider the following:  

  • Find the optimal temperature for processing conditions – not too hot, not too cold
  • Reduce lamp temperature
  • Increase coolant or increase speed

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