Why Does Printed Film Become Oily After Storage? Causes and Solutions for DTF Printing

Introduction: The Problem of Oily Printed Film After Storage

In the world of DTF (Direct-to-Film) printing, one of the common issues encountered is printed film becoming oily after being stored for a period of time. This phenomenon can affect the quality of your prints and cause concerns for manufacturers and printers. Understanding why this happens and how to resolve it is key to maintaining high-quality output and ensuring a smooth printing process.

In this article, we’ll delve into the possible causes of oily film and provide practical solutions to prevent and resolve the issue.

What Causes Printed Film to Become Oily After Storage?

Cause 1: The Role of Humectants in DTF White Ink

DTF white ink typically contains humectants, such as glycerin, which are added to prevent print head clogging. Glycerin is a thick, transparent liquid that is hygroscopic, meaning it can absorb moisture from the air. While it plays a vital role in the ink’s formulation, glycerin doesn’t evaporate or dry out completely. If the drying process during printing is insufficient, glycerin may remain on the surface of the printed film. Over time, this un-dried glycerin migrates to the surface, giving the printed film a greasy or oily appearance.

Cause 2: Insufficient Temperature During Powder Curing

Proper curing is crucial for the DTF process. If the temperature during the powder curing phase is not high enough, or the heating time is too short, the powder may not bond fully to the film. This insufficient curing can cause the glycerin or other ink components to migrate to the surface, leading to an oily film. Ensuring the correct curing conditions is essential to prevent this issue.

Cause 3: Non-Permeable Fabric and Surface Oil Migration

Certain fabrics or films that lack proper permeability can exacerbate the problem. When the printed film has limited airflow or moisture regulation, it becomes easier for oils to migrate to the surface. This can cause the phenomenon of “surface oil” where the print appears shiny and greasy, compromising the final product’s quality and longevity.

How to Prevent Oily Printed Film: Effective Solutions

Now that we know the possible causes of oily printed film, let’s explore solutions to prevent and address this issue:

Solution 1: Store Printed Film in Sealed, Controlled Environments

One of the most effective ways to prevent oily film after storage is to ensure proper storage conditions. Store the printed film in a sealed, airtight environment, away from moisture and fluctuating temperatures. This will minimize the absorption of moisture and reduce the chances of glycerin migrating to the surface.

Tips for Optimal Storage:

• Store printed films in cool, dry places.
• Avoid areas with high humidity or rapid temperature changes.
• Use sealed packaging or plastic wraps to keep moisture out.

Solution 2: Reheat Oily Films Using the Powder Shaker Machine

If you notice that the printed film has become oily after storage, you can reprocess it using the powder shaker machine. Simply put the film back into the shaker and reheat it to ensure that the glycerin and other components are fully dried. The heat will help evaporate any remaining moisture and ensure the print is properly cured.

Solution 3: Ensure Proper Temperature and Heating Time During the Curing Process

To prevent oily films in the first place, make sure that the curing temperature and time are set correctly during the powder curing process. Adequate heat is essential for properly binding the powder to the film and ensuring that all components of the ink are dry and stable.

Key Parameters for Proper Curing:

• Set the powder curing temperature to the recommended range.
• Increase the heating time if necessary to ensure complete curing.
• Monitor the process to prevent over or under-heating.

The Importance of Preventing Oily Film in DTF Printing

Preventing oily films is crucial for several reasons:

• Print Quality: Oil on the surface of the film can lead to poor adhesion of the ink to the fabric during the transfer process, affecting print sharpness and durability.
• Long-Term Storage: Films that are oily may degrade or lose their print quality over time, leading to wastage and product rejection.
• Customer Satisfaction: For printers dealing with clients, ensuring that the printed film remains of high quality after storage helps build trust and satisfaction.

Conclusion: Maintain Quality with Proper Handling and Storage

The issue of oily printed film after storage is often caused by insufficient drying during the printing process, improper curing, or inadequate storage conditions. By understanding the underlying causes and implementing the right solutions, such as controlled storage and proper powder curing, you can prevent this issue and maintain high-quality prints.

By following the steps mentioned above, you can ensure that your DTF printing process yields consistent, professional results, free from oily or greasy film issues. Always prioritize optimal curing and proper storage to extend the shelf life of your prints and deliver the best quality to your customers.