Why Printed Films Develop Water Bubbles After Storage and How to Prevent It

Water bubbles in printed films are a common problem faced by many in the printing industry. These bubbles can appear after storing the films for a few days, affecting the quality and durability of the prints. In this article, we’ll explore the reasons behind this issue and provide practical solutions to prevent water bubbles from forming.

Understanding the Cause of Water Bubbles in Printed Films

The Role of Heating and Curing in Ink

Many DTF printers have a built-in heating function that cures approximately 40-50% of the white ink before the film enters the powder machine. The thermostat is typically set between 110°C to 140°C, which allows the powder to melt and act as a primer. However, even with this partial curing, around 30-40% of water remains trapped between the PET film and the powder primer. Over time, this residual water may vaporize and form bubbles or blisters on the surface of the film.

The Impact of Moisture on Film Quality

The remaining water in the white ink can become problematic as it condenses, leading to water bubbles. These bubbles are more likely to form if the moisture is unable to escape properly during storage.

Factors That Influence Water Bubble Formation

Humidity Levels in the Storage Environment

The humidity in the storage area plays a significant role in whether or not water bubbles will form. High humidity increases the chances of moisture accumulating on the printed film, which, if not properly evaporated, leads to water bubbles over time.

Film Quality Matters

The quality of the film used for printing is another critical factor. High-quality films with strong water resistance properties help in absorbing moisture more effectively, reducing the likelihood of water bubbles. In contrast, lower-quality films may not effectively allow moisture to evaporate, increasing the chances of bubble formation. AGP offers high-quality cold-peel and hot-peel films that can cater to your specific needs. For more information on the differences, you can check out my previous article on Hot Peel vs. Cold Peel Films.

How to Avoid Water Bubbles in Printed Films

Optimizing the Drying Process

A well-controlled drying process is key to avoiding water bubbles in printed films. If the powder machine manufacturer can divide the drying process into three stages, it can significantly reduce the chances of water bubbles. Here’s how it works:

• Stage 1: 110°C – The powder begins to melt, and the remaining water evaporates, turning into gas.
• Stage 2: 120-130°C – This stage further heats the glycerol, allowing any residual moisture to escape.
• Stage 3: 140°C – At this point, the powder is completely melted and acts as a primer, joining seamlessly with the print.

By following this three-stage process, you ensure that most of the moisture is removed, leaving behind a perfectly cured and smooth print.

Storage Tips for Printed Films

Proper storage of printed films is just as important as the printing process itself. Here are some key tips to ensure your printed films stay bubble-free:

• Seal the Films Properly: Always store printed films in sealed conditions to prevent moisture from entering.
• Monitor Humidity: Pay attention to the humidity levels in your storage area. Ideal storage conditions should be cool and dry to avoid moisture accumulation on the films.

Conclusion

Water bubbles in printed films can be a major issue if not properly managed. By understanding the causes—such as improper curing, high humidity, and low-quality films—you can take the necessary steps to prevent this problem. Implementing a well-controlled drying process and storing films in a dry, sealed environment will go a long way in ensuring your prints remain bubble-free. If you're experiencing frequent issues with water bubbles, consider upgrading to high-quality cold-peel or hot-peel films like those offered by AGP for better results.