05 Nov Hot Filling & Its Impact on Labelling in Food & Beverage Packaging
Why Hot Filling Still Matters in Modern Food Production
The food and beverage market is increasingly driven by shelf stability, clean-label expectations, and reduced preservatives, hot filling remains a cornerstone for many beverage and sauce manufacturers. The process involves heating a liquid product, like juices, jams, or condiments to sterilizing temperatures (typically 82–95 °C / 180–203 °F) before filling it into containers. This eliminates microbial growth and ensures safety without relying on chemical preservatives.
The challenge? When that container moves down the line, it’s still hot. Even after capping and cooling, the combination of heat, internal vacuum, and moisture can distort the container’s shape and compromise label adhesion if the wrong materials or technologies are used.
What looks like a small issue but a label that wrinkles, bubbles, or peels can undermine a brand’s image and even lead to product rejections at retail.
Thermal Stress: A Hidden Enemy for Labels
Hot filling exerts several forms of stress on both the container and label:
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- Container Shrinkage or Expansion:
PET and PP containers expand slightly when filled hot, then contract as they cool. Labels applied too early or with low-flex materials may wrinkle or shift position. - Moisture & Condensation:
Cooling tunnels or air rinsers often create surface condensation. This thin film of water is enough to disrupt adhesive bonding if the adhesive isn’t designed for it. - Surface Temperature Variations:
The labeler must deal with fluctuating container surface temperatures, sometimes above 40 °C (104 °F), affecting both adhesive tack and cure rate. - Vacuum Panels & Panel Deformation:
Hot-filled bottles are designed with vacuum panels to handle internal pressure changes. Label placement must align perfectly with these features to prevent air bubbles or tears.
- Container Shrinkage or Expansion:
Matching Labeling Technology to Hot Fill Conditions
Choosing the Right Fit
Three labeling technologies dominate the market: Pressure-Sensitive, Hot-Melt, and Cold-Glue. Each performs differently under heat, moisture, and speed.
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- Pressure-Sensitive (PS) Labels
These self-adhesive labels are ideal for high-speed operations and versatile designs. Modern PS adhesives can handle elevated temperatures, but selection is critical:
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- Choose adhesives with high Shear Adhesion Failure Temperature (SAFT) ratings.
- Opt for flexible label films (like BOPP) that conform to container shrinkage.
- Ensure proper container surface preparation, even a small amount of moisture can cause flagging.
Best for: Premium beverages, sauces, and condiments where high visual quality is key.
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- Hot-Melt Labels
Hot-melt adhesives are applied molten and quickly set upon cooling. They offer excellent adhesion to both glass and plastic containers, even in warm or humid environments.
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- Resistant to condensation.
- Strong bonding for high-speed, continuous operations.
- Low adhesive waste when paired with modern rotary labelers.
Best for: PET bottles exiting hot-fill lines still above ambient temperature, or containers with textured or uneven surfaces.
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- Cold-Glue Labels
Traditional wet-glue systems remain a cost-effective choice for glass jars and certain rigid containers. However, in hot-fill environments:
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- Surface moisture and heat can interfere with drying.
- Label stock must be absorbent enough for the adhesive to cure properly.
Best for: Classic applications like jams, sauces, and glass beverage bottles on slower lines.
Engineering the Perfect Hot-Fill Labeling Line
Success lies in the integration, not just the technology. Manufacturers should consider:
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Cooling & Drying Before Labeling:
Integrate air knives or drying tunnels before labeling to eliminate condensation. -
Proper Conveyor Timing:
Allow containers to reach a safe labeling temperature (usually below 38 °C / 100 °F). -
Label Stock Selection:
Use thermally stable materials such as polypropylene or shrink-compatible films that resist deformation. -
Vacuum Panel Alignment:
Label placement must accommodate vacuum panel zones on PET bottles. Rotary labelers with precision servo control, like Gernep’s modular systems, ensure consistent alignment. -
Testing & Validation:
Always perform adhesion tests across temperature ranges and during full production speeds.
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How Gernep Labeling North America Supports Hot-Fill Operations
With rotary systems designed for Pressure-Sensitive, Hot-Melt, and Cold-Glue applications, or hybrid combinations, Gernep Labeling Machines help manufacturers handle high-speed, thermally sensitive packaging lines with precision.
Our modular rotary machines are engineered to integrate seamlessly after hot-fill and cooling stages, maintaining accuracy and adhesion even under challenging conditions. Whether you’re labeling juices, dressings, or ready-to-drink teas, we build for your process, not the other way around.
Final Thoughts
Hot filling brings undeniable advantages, longer shelf life, safer products, and greater flexibility in distribution, but it also demands precision at every stage of production. The right labeling system isn’t just about keeping a label in place; it’s about ensuring consistency, efficiency, and brand integrity when conditions get tough.
Selecting technology that aligns with your line’s temperature profile, speed, and container type can make the difference between constant rework and smooth, uninterrupted performance. That’s where working with an experienced partner matters.
We’ve spent decades helping manufacturers integrate reliable labeling systems that fit their real-world conditions, not just the ideal ones. Our goal is simple: to make sure your labels look as good at the end of the line as your product tastes when it reaches the shelf.
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