Keys to Avoiding and Correcting Common Label Application Problems
Are you having trouble applying product labels correctly? Do they want to skew or flag? Do they fall off before they reach the end user?
These label application problems can stem from a variety of sources, including the container, the label, the manufacturing environment, and even your label storage methods. Here’s some critical troubleshooting advice for when you encounter common label defects.
Table of Contents
- Keys to Avoiding and Correcting Common Label Application Problems
- Labels Aren’t Sticking to the Containers
- Examine Die Cut
- Consider Environmental Conditions and Contaminants
- Assess Surface Energy
- Skewing, Wrinkling, Peeling, Air Bubbles, and Flagging
- Skewed Labels
- Flagging Issues
- Wrinkle Concerns
- Troubleshooting Air Bubbles
- Labels Aren’t Sticking to the Containers
3. Get a Labeling Solution That Works for Your Business
Labels Aren’t Sticking to the Containers
This is one of the most common label defects because several labeling process factors are at play to promote adhesion. If you just switched to a new container or label material, make sure you’re using compatible adhesive. It needs to work with the temperature of the container and the environment, not just the container’s surface.
High temperatures increase tackiness, causing problems with label separation. Low temperatures make adhesives brittle, keeping them from wetting out. Talk to your label provider about adhesives that work best for your product’s temperature range.
To reduce temperature-related problems, store your labels as close to ground level as possible. Heat rises, which means high shelving in your warehouse may be more than 20 degrees hotter than ground-level shelves. To prevent moisture contamination in high-humidity areas, keep your labels in sealed containers or wrapped in plastic until they’re loaded onto the labeler. If there is a large temperature difference between your storage location and your labeling station, store spare reels near the label station to give them time to reach the manufacturing area’s room temperature.
Examine Die Cut
Were your labels cut correctly? Poor die strikes can cause problems when it’s time to lift the label off of the backing. Deep strikes push the adhesive into the liner, while shallow strikes don’t cut through the face stock. Cutting with a dull die pushes the label adhesive off the sides of the label and onto the untreated edge of the label liner. Even if the labels are cut correctly, they can still be hard to remove if the liner doesn’t have enough release agents.
Consider Environmental Conditions and Contaminants
The application environment can be just as important as the labeling equipment and substrate. Surface contamination prevents label adhesives from bonding with the container surface. For example, condensation is a common issue for beverages. In most cases, this can be solved by blowing off surface moisture with an air knife placed before the labeling station. While adhesives are available for moist surface application, they have their limits and work best on labels that experience condensation after labeling.
Oil on the surface of the container also prevents adhesive contact. While this may be due to processing errors, it’s often traced to handling. Bare hands transfer skin oil to the container, preventing a strong bond. Make sure your workers are wearing gloves when they handle products.
Additionally, it’s important to keep in mind that adhesives need time to cure. Depending on the formula, this can take anywhere from 2 to 48 hours. Containers shouldn’t be shipped until this curing time has finished, or the label may peel off during handling. While an adhesive may work on cold products, it may not cure at low temperatures, so you may need to label the containers before filling them.
Assess Surface Energy
Are you using new plastic containers? Plastics with low surface energy have trouble bonding to adhesives because they don’t let the adhesive wet out, which reduces contact. The good news is that containers are available with treated surfaces that increase surface energy. This is achieved with heat processing or chemical treatments. Untreated polypropylene and low-density polyethylene have the lowest surface energy, making them the most difficult to label.
For the wipe-on application on pressure sensitive labels, the rollers and roller pressure affect label conformation. Solid containers like glass and metal work best with high-pressure and soft rollers. Flexible containers, like most plastics, get better conformation with low pressure and soft rollers. Tamp blow systems depend on air for application, helping the label conform to any surface. To find out which method is right for your products, check out our blog, “Tamp-Blow vs. Wipe-On Label Application: Which One Is Better For Your Business.”
Skewing, Wrinkling, Peeling, Air Bubbles, and Flagging
In most cases, label defects like skewing, wrinkling, peeling, air bubbles and flagging are caused by application issues or material problems.
Are you using the right settings on your labeling machine? Our automatic label applicators have PLCs that can store calibration settings for multiple containers. Always check the settings when switching to a different container.
Skewed Labels
Is your label designed around the slope of your containers? While plastics may appear flat, they usually have a small taper to help them release from molds. While this may be as little as one or two degrees, it’s enough to cause label skew on cylindrical containers. The label needs a slight curve to compensate for the container’s shape.
Flagging Issues
Flagging issues are typically related to label size. Using a label that’s too big can result in flagging. In most cases, you need to leave 1/8-1/4 inches of space around the edges of the container side. For wrap-around labels used on rectangular containers, blank space should be added to the edges of each side of the label. This gives some leeway for minor imperfections in the container surface or the label.
Wrinkle Concerns
The cheaper a container is, the more likely it has surface defects. This can cause the label to skew, flag, or wrinkle as applied, a common problem with glass bottles and plastic containers. If you can’t replace your containers, switch to a flexible face stock that can conform to uneven surfaces. Increasing the empty space between the label and the edges of the container also gives you more room to account for these variations in shape.
Troubleshooting Air Bubbles
If you’re labeling plastic containers, you need to account for off-gassing. All plastics release small amounts of gas over time, which leads to bubbling under the label. To prevent this, you need a face stock and coatings that are permeable, so these gasses can pass through without peeling up the label.
In addition to the common concerns mentioned above, there are some other notable issues to be aware of.
Are your labels moving around before they reach the label applicator? Improper storage can flatten the label roll or let the labels slide across the liner. To prevent this, always stack label reels on their sides. While release agents help the label peel away from the liner, too much can make the labels slide around during storage or application.
Static electricity is generated when electrical charges pass between objects. In manufacturing, this usually occurs between containers and conveyor belts. If the container and the label have the same charge, they repel each other. If they have the same charge, the label can peel off the backing before it’s pressed on, reducing contact with the container. With either charge, this can cause wrapping and skewing problems. Eliminators and ionizers both use different methods to neutralize this electrical charge. Electrical charges are also absorbed by humid air, making label application problems from static charge more common on cold and dry days.
Get a Labeling Solution That Works for Your Business
If you’re experiencing downtime due to label printing issues, CTM Labeling Systems can help. Our distributors work with you to find the right equipment and production line setup so that you achieve optimal label application, taking every factor into account, including floor space, environment, and containers.
We build machines that are easy to modify and can work with almost any type of packaging, from wine bottles to bulk industrial pails containers. Find label printers and applicators that fit your needs. Contact us to get started.
