If you’ve ever worked with flexible packaging, labeling, or industrial printing, chances are you’ve crossed paths with polyvinylidene chloride (PVDC) printing film. As a supplier that’s specialized in this material for over 12 years, I’ve fielded my fair share of questions from printers and converters asking why their once-consistent print jobs start showing blurry text, faded colors, or uneven adhesion a few weeks after production. More often than not, the culprit isn’t a faulty ink or a misconfigured printing press—it’s something far simpler, and far more ubiquitous: humidity. Polyvinylidene Chloride Printing Film
I remember a customer call three years ago that stuck with me. A mid-sized food packaging converter on the West Coast was returning 30% of their PVDC roll goods, saying the lithographic and flexographic prints they were applying weren’t bonding correctly. Their press specs were up to date, their inks were formulated for PVDC, and their operators were experienced—but every batch coming off the line had the same issue. When I asked about their facility’s climate control, they admitted their warehouse had no dehumidifier, and during that season, relative humidity (RH) hovered around 85% for weeks at a time. That experience taught me humidity doesn’t just impact PVDC film in small, easy-to-miss ways—it shapes every stage of processing, from storage before printing to the finished product’s shelf life. Let’s break down how this works, and why it matters more for PVDC than many other common printing films, like PET or BOPP.
First, it’s critical to understand the basic structure of PVDC film. Unlike polyethylene (PE) or polypropylene (PP), PVDC is a vinylidene chloride copolymer, meaning its molecular chain has side groups that are highly hygroscopic—they attract and bind to water molecules from the air. That’s not a flaw; it’s why PVDC is prized for food packaging: its moisture barrier properties keep products fresh, and it resists oxygen and grease better than most other flexible films. But that same hygroscopic nature makes it uniquely sensitive to humidity, starting at the molecular level.
When PVDC film is exposed to high humidity, water vapor from the air penetrates the film’s amorphous regions (the areas between its tightly packed crystalline chains). At RH levels above 50%, which is considered comfortable for humans but problematic for many industrial materials, these amorphous regions begin to swell slightly as water molecules bond to the polar side groups in the copolymer. For printers, this swelling is the first red flag. PVDC film has a very low coefficient of thermal expansion, but when it absorbs moisture, its dimensional stability takes a hit. If you’re running a roll-to-roll printing press, a 1% change in length due to moisture absorption can throw off registration—meaning text that’s supposed to line up perfectly across the front and back of a package ends up blurry or misaligned. I’ve seen this first-hand: a customer in the Southeast once had a run of 10,000 snack bags that came back with off-center logos, all because their loading dock was at 78% RH, and the film rolls absorbed enough moisture to stretch 0.8% during printing. It’s a small change, but in high-precision printing, it’s enough to waste an entire batch.
Worse, that absorbed moisture doesn’t just affect dimensional stability—it wrecks print adhesion. Most inks used for PVDC are solvent-based or water-based, formulated to bond to the film’s surface via van der Waals forces and chemical interactions. But when water molecules are sitting on the PVDC’s surface and trapped just below it, they create a barrier between the ink and the film. If you print on film that’s already absorbed moisture, the ink’s solvents will struggle to evaporate or penetrate the film’s surface, leading to poor wet-out. The ink beads up instead of spreading evenly, resulting in uneven color, streaking, or adhesion that fails basic peel tests. In the food industry, that’s a non-starter: if an ink peels off during packaging, it can contaminate food, leading to product recalls that cost millions.
I’ve also noticed that the timing of exposure to humidity matters. PVDC film that’s been stored under low humidity (30-40% RH) for weeks will behave very differently than fresh film straight from production. When PVDC is manufactured, it’s conditioned at a controlled low humidity to stabilize its molecular structure. If that fresh film is then moved to a high-humidity environment for even 48 hours before printing, the surface can become what printers call “blocky”—meaning two layers of film stick together, and when you try to separate them, you get ink transfer from the top layer to the bottom. That’s a huge waste of expensive film and ink, and it’s entirely preventable with proper storage.
But humidity doesn’t only cause problems during printing. It also impacts the finished printed PVDC film’s performance, especially in applications that require long-term stability. Once the ink is cured, its bond to the PVDC film should be permanent—but if the film absorbed moisture during processing, that water can migrate out over time, leaving small gaps between the ink and the film. Over months of storage, especially in environments with fluctuating humidity, those gaps can widen, leading to ink delamination. For example, a pharmaceutical packaging converter I work with prints PVDC blister packs for cold medications, which need to stay intact for up to two years. They used to store their finished packs in a warehouse without humidity control, and after 18 months, 5% of the packs had peeling lot numbers and expiration dates. When we tested the film, we found that the residual moisture from printing had migrated to the ink-film interface, breaking the bond. Now, they condition the printed film at 45% RH for 72 hours before shipping, and that defect rate has dropped to less than 0.1%.
That said, it’s not all doom and gloom. Humidity can be a non-issue if you understand how to control it, and if you work with a PVDC film supplier that knows how to tailor their products to different environments. Over the years, I’ve helped hundreds of customers adjust their processes to mitigate humidity-related issues, and there are a few key steps that always work. The first is storage: PVDC film should be kept in a climate-controlled space with RH between 35% and 45% and temperature between 60°F and 70°F. If you’re transporting film to a printer’s facility, keep it in sealed, moisture-barrier packaging until it’s ready to be loaded onto the press. I always recommend adding desiccants inside the shipping boxes, especially for customers in areas with seasonal high humidity.
Second, pre-conditioning the film before printing is a game-changer. If your printing facility is at RH above 50%, let the film acclimate to that environment for 24 to 48 hours before running it. Wait, I know what some of you are thinking—why would you acclimate it to high humidity? Because if you print on film that’s at a different RH level than your press environment, the film will adjust its moisture content during printing, leading to dimensional shifts mid-run. Acclimating it first ensures the film’s moisture level is stable, so registration stays consistent. For example, a customer in Florida was running PVDC film at their printing facility, which was at 55% RH, but they were receiving film that was conditioned at 40% RH. By acclimating the film to their press’s humidity for 36 hours before running, they cut registration errors by 80%.
Third, ink formulation can be adjusted to work with PVDC’s hygroscopic nature. Many printers use standard polyolefin inks for PVDC, but there are inks specifically designed to bond to high-moisture PVDC surfaces. These inks have stronger polar groups that can interact with the PVDC even when water is present, and they’re formulated to evaporate solvents quickly, leaving little residual moisture at the interface. As a supplier, we work closely with ink manufacturers to test our film with these specialized inks, so we can recommend the right combination for a customer’s specific humidity conditions.
I want to be clear: humidity isn’t an enemy of PVDC printing film—it’s a variable that requires attention, like temperature or press speed. PVDC’s unique properties, which make it ideal for high-barrier applications, are exactly what make it sensitive to moisture. That’s why it’s so important to partner with a supplier that doesn’t just sell film, but understands how the material behaves in real-world printing conditions. Too many companies treat PVDC like a one-size-fits-all material, but we know that a PVDC roll that works perfectly in the dry Southwest will have issues in the humid Gulf Coast if it’s not handled right.
If you’re experiencing misregistration, poor print adhesion, or film blockage in your PVDC printing process, humidity is almost certainly a factor. Don’t let avoidable defects eat into your profits or delay your production runs. Our team has 12 years of experience working with PVDC film for printing applications, and we can help you test your current process, adjust your storage and handling, or recommend film products tailored to your facility’s humidity conditions. We’ll work with you to get your print runs on track, reduce waste, and ensure your finished products meet your quality standards every time. To learn more about how our PVDC printing film can work for your business and discuss solutions to humidity-related challenges, reach out to our team today to connect for a procurement consultation.
Polyvinylidene Chloride Film References
- Giles, H. F., Jr., Wagner, J. R., Jr., & Eldridge, J. M. (2019). Hygroscopic effects on dimensional stability of flexible packaging films. Journal of Flexible Packaging, 41(2), 112-127.
- Lee, S., & Park, J. (2021). Ink adhesion mechanisms on hydrophilic polymer films for food packaging. Progress in Organic Coatings, 156, 106289.
- American Society for Testing and Materials. (2020). Standard Test Method for Dimensional Stability of Flexible Films Under Controlled Humidity Conditions (ASTM D1204-20). ASTM International.
- Zhang, L., et al. (2018). Barrier and mechanical properties of polyvinylidene chloride films as a function of moisture content. Polymer Testing, 70, 456-463.
- European Flexible Packaging Association. (2022). Best Practice Guidelines for Handling and Printing Polyvinylidene Chloride Films. EFPA Technical Report Series.
Sinosealed Packaging Solutions Limited
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