Proper Storage Conditions for Flexible Packaging Films: Temperature and Humidity Guidelines

You just received pallets of premium polypropylene film rolls for your packaging line, and now they’re sitting in your warehouse. Three months later, you notice the film isn’t feeding smoothly, seals aren’t holding, and quality issues are mounting. The problem isn’t the film itself. It’s how you’ve been storing it.

Getting Temperature Right for Your Films

Temperature control forms the foundation of proper film storage. Most flexible packaging films perform best when stored between 60°F and 75°F. This range prevents material degradation while maintaining the physical properties that make these films effective.

Higher temperatures create several problems. Heat can cause films to soften, leading to rolls that telescope or collapse. Adhesive coatings on lidding films may become tacky, causing unwanted blocking. Printed films risk ink migration or color shifts. For heat-sensitive materials like certain polyethylene grades, extended exposure to temperatures above 85°F can permanently alter the material structure.

Cold storage presents different challenges. Temperatures below 50°F make films brittle and prone to cracking during unwinding. Cold films also need adequate warm-up time before use. Running cold film through packaging equipment leads to poor heat sealing, inconsistent forming, and mechanical failures. Some operations make the mistake of pulling film directly from cold storage to production lines, wondering why their seal strength suddenly drops.

Here’s what you need to know about temperature management:

1. Maintain consistent temperatures rather than allowing daily fluctuations
2. Allow cold films to acclimate for 24-48 hours before use in a temperature-controlled area
3. Keep films away from heat sources like radiators, HVAC vents, or direct sunlight through windows
4. Monitor seasonal changes that might affect warehouse temperatures
5. Use climate-controlled storage for high-value or sensitive film materials

What Humidity Does to Your Film Inventory

Relative humidity between 40% and 60% provides the ideal environment for most flexible films. This range prevents moisture-related problems while avoiding the issues that come with excessively dry conditions.

High humidity creates moisture absorption in hygroscopic materials. While clear polypropylene film and polyethylene films resist moisture penetration, the paper cores they’re wound on readily absorb water. Wet cores expand, crushing the inner wraps of film and creating tension variations throughout the roll.

Condensation poses an even greater threat. When you move film from cold storage to a warm, humid production area, moisture condenses on the film surface. This invisible layer of water prevents proper heat sealing, causes printing issues, and can lead to contamination concerns in food packaging applications.

Low humidity below 30% generates static electricity problems. Film becomes clingy and difficult to handle. Static attracts dust and contaminants that compromise package integrity. Production lines experience frequent jams as charged film sheets repel or attract each other unpredictably.

Signs your humidity levels are wrong:

• Excessive static cling making film hard to separate
• Visible moisture or condensation on film surfaces
• Paper cores that feel damp or show water staining
• Blocking where film layers stick together stubbornly
• Inconsistent seal strength across production runs

How to Stack and Position Rolls Correctly

How you physically store film rolls matters as much as temperature and humidity. Improper stacking leads to crushed cores, deformed rolls, and material that won’t run properly on packaging equipment.

Always store rolls vertically when possible, standing on end rather than laying flat. This prevents the weight of upper rolls from crushing lower ones. If vertical storage isn’t feasible, limit horizontal stacks to three rolls high for smaller diameters and two rolls high for large outside diameter rolls.

Position rolls so the film unwinds in the correct direction for your equipment. Mark each roll clearly with arrows indicating the proper feed direction. This simple step prevents confusion and reduces setup time during production changeovers.

Create adequate spacing between rolls and pallets. Air circulation prevents localized hot spots and moisture accumulation. Avoid storing film directly on concrete floors, which can transfer cold temperatures and moisture. Use pallets or elevated platforms to maintain consistent environmental conditions around all rolls.

Three rules for handling film rolls safely:

1. Never roll film horizontally across floors as this can pick up debris and damage the outer wraps
2. Use proper lifting equipment for rolls over 50 pounds to prevent core damage from improper handling
3. Keep protective end caps in place until you’re ready to load the roll onto equipment

Light Damage You Can’t See Until It’s Too Late

UV light and prolonged exposure to fluorescent lighting degrade many polymer films over time. While the effect develops slowly, extended storage under bright lights can cause yellowing, brittleness, and loss of physical properties.

Metalized films and certain printed films are particularly susceptible to light-induced degradation. Even clear polypropylene and polyethylene films show measurable property changes after months of bright light exposure.

Store films in their original protective packaging whenever possible. The outer wrapping shields materials from light while also providing a barrier against dust and contamination. If you’ve removed packaging for sampling or inspection, rewrap exposed rolls with opaque sheeting.

Keep storage areas dimly lit when films aren’t being actively handled. Motion-activated lighting provides adequate illumination when needed while minimizing unnecessary light exposure during long-term storage.

Film types most vulnerable to light damage:

1. Metalized polypropylene films lose reflective properties and develop surface defects
2. Printed films with organic inks experience color fading and shift
3. PLA compostable films degrade faster when exposed to UV light
4. Vacuum skin packaging films can develop haze and reduced clarity

Film Type	Ideal Temperature Range	Recommended Humidity	Special Considerations
Polypropylene (OPP)	65°F – 75°F	40% – 55%	Avoid rapid temperature changes
Polyethylene (LDPE, LLDPE)	60°F – 75°F	40% – 60%	More tolerant of humidity variations
PLA Compostable Films	60°F – 70°F	35% – 50%	Sensitive to moisture; shorter shelf life
Vacuum Skin Packaging	65°F – 75°F	40% – 55%	Store away from light sources
Lidding Films	65°F – 75°F	40% – 50%	Keep adhesive side protected
Printed Films	65°F – 75°F	40% – 55%	Protect from UV light exposure

When Fresh Matters: Film Shelf Life Reality

Flexible packaging films don’t last forever, even under perfect storage conditions. Most films have an optimal usage window of 12 to 18 months from manufacture. PLA compostable films typically have shorter shelf lives around 6 to 12 months due to their biodegradable nature.

Implement a first-in, first-out inventory system. Clearly date all incoming materials and position newer stock behind older rolls. This practice ensures you use materials within their optimal performance window and reduces waste from expired film.

Consider the specific application when planning inventory levels. Critical food packaging operations requiring consistent seal strength should use fresher film. Less demanding applications might tolerate older materials without quality issues.

Watch for visible signs of aging. Yellowing, brittleness, unusual odors, or changes in flexibility indicate material degradation. When in doubt, test a sample roll before committing an entire production run to questionable material.

Testing protocols for older film stock:

1. Run a seal strength test on production equipment with actual settings
2. Check for blocking by unwinding several layers and observing separation
3. Inspect for brittleness by flexing a sample and looking for cracking
4. Verify optical properties match specifications for clarity and haze

Storage Errors That Cost You Money

Understanding what not to do helps as much as knowing best practices. These frequent errors lead to the majority of storage-related film problems:

• Storing different film types together without considering their unique requirements
• Placing films near loading dock doors where temperature and humidity fluctuate dramatically
• Removing protective packaging too early and exposing films to environmental factors
• Stacking rolls too high and crushing materials at the bottom of the pile
• Ignoring seasonal changes that affect warehouse conditions
• Using damaged or compromised films rather than properly disposing of degraded material
• Exposing adhesive-coated films and laminated film packaging to high-humidity environments that compromise bond strength. 

Routine Questions Regarding Storage

How long can I store flexible packaging films?

Most polypropylene and polyethylene films maintain quality for 12-18 months under proper conditions. PLA compostable films have shorter shelf lives of 6-12 months. Always check manufacturer recommendations for specific materials.

What happens if the film gets too cold?

Cold film becomes brittle and may crack during unwinding. It also needs extended warm-up time to achieve proper heat sealing temperatures. Plan for 24-48 hours of acclimation before using cold-stored film.

Can I store film in an unheated warehouse?

Only if temperatures remain above 50°F consistently. Seasonal temperature swings in unheated spaces often fall outside acceptable ranges, particularly in winter months.

How do I know if humidity is affecting my film?

Look for blocking between layers, difficulty unwinding, poor seal strength, or moisture on film surfaces. Wet or expanded paper cores also indicate humidity problems.

Is vertical or horizontal storage better?

Vertical storage standing on end is ideal as it prevents crushing from stacked weight. If horizontal stacking is necessary, limit height to 2-3 rolls depending on size.

Protecting Your Investment in Quality Films

Proper storage isn’t complicated, but it requires attention to detail and consistent practices. The investment in climate control and organized storage systems pays for itself through reduced waste, fewer production problems, and consistent package quality.

Think of film storage as an extension of your quality control program. You wouldn’t allow raw materials to sit in unsuitable conditions before production. The same principle applies to your packaging films. Creating the right environment protects these precision materials so they perform exactly as designed when you need them.

Best practices checklist for long-term film storage success:

• Install temperature and humidity monitors in storage areas with data logging
• Create designated zones for different film types with specific requirements
• Train all warehouse staff on proper film handling techniques
• Schedule quarterly audits of storage conditions and inventory rotation
• Document storage conditions as part of quality control records
• Establish relationships with suppliers who provide storage guidance

Get the Right Films and Storage Guidance from RTG Films

RTG Films has distributed flexible packaging films since 1995. Our product line includes polypropylene, polyethylene, lidding films, vacuum skin packaging materials, PLA compostable films, and custom printed films. As an AIB-certified facility, we provide detailed storage recommendations for every product.

Contact our experts now to discuss your flexible packaging needs and get expert guidance on maintaining film quality and securing your goods with confidence.