Curl Continued: Tips for Resolving Media Curl Off Press

In our last post, we provided insight on how much curl printers can typically tolerate. Today, we offer a few tips for how to best resolve media curl issues off press.

If experiencing media curl off press, first and foremost, take a closer look at the environmental conditions of your facility. Dry or humid air can easily be a culprit of media curl. Ideally, it is best to keep your facility temperature consistently at 72° F and 50% relative humidity (RH). Proper RH can be achieved with a humidifier or dehumidifier. Additionally, the material should have time to acclimate to the environment. If possible, let the material acclimate in your facility for 72 hours.

If neither environmental conditions nor material acclimation are causing the media to curl, the following tips can offer added insight into the reason for the curl and how you can possibly resolve it:
 

  • Look at the direction of the curl.
    • If you notice curl that mimics or is opposite the shape of the roll (up or down), the curl is most likely being induced by tension. And, if mimicking the shape of the roll (downward), it could be “core set” whereby it’s naturally set to the shape of the roll.
    • If you pinpoint curl whereby the slit edge sides of the roll are not flat (up or down), the curl is most likely an imbalance of moisture between the media face and liner. For example, one has lost or gained moisture over the other, and the associated shrinking is creating tension between the two materials. If environmental conditions are dry, the direction the media is curling toward is likely losing moisture. If conditions are humid, the side the media is curling away from is likely gaining moisture.
    • If you have a diagonal direction curl, the reason for the curl may be a combination of both tension and moisture.

  • Check unconverted material stock for lay flat.
    • If the unconverted material is flat, curl is likely being induced during converting.
    • To try to resolve the issue, dissect the press and look for any areas that could be causing the material to curl. Signs to look for include:
      • Excessive ink lay down: Ink has water content which adds moisture to the side being printed. Turn off the ink printing and see if the problem still exists.
      • Excessive or insufficient dryer oven heat: Most ink stations have basic heat settings, generally similar to OFF / LOW / HIGH. Reducing heat may address the issue. Keep in mind that heavier or thicker media and coated media, such as high gloss, semi-gloss, and matte will be more heat resistant.
      • Heavy die strike or dull dies
      • Tight turns the media takes when passing through the press

If the media is curl-free when leaving your facility, but curling at the end-user location, the cause of the curl is likely due to poor end-user environmental conditions or improper packaging. Recommend the end-user check conditions – again aiming for 72° F and 50% RH – in areas where the media is being used and stored. Also, ensure the end-user allowed the media to acclimate for 72 hours. Finally, suggest inspection of the media packaging for potential issues and improvements.

For added guidance, reach out to your material supplier.

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