Hey there,
If you’ve ever stopped to think about how that tube of cream, gel, or oral paste you grab from the pharmacy actually stays safe until you twist open the cap, you’re not alone. For years, I used to just assume “it’s a tube—of course it seals.” Then I started running this Medicines Packaging Tubes supplier, and let me tell you, sealing those tubes? It’s way more than a twist. Bad sealing means expired meds, wasted product, even safety risks for whoever’s taking that medicine. I’ve seen first-hand what happens when a seal isn’t done right: a client’s entire batch of antibiotic gel went bad because the crimp at the top split during shipping, and they lost thousands in product and customer trust. So today, I’m breaking down how we do it—effectively, consistently, and without skipping any steps—because if you’re dealing with medicine packaging, this stuff matters. Medicines Packaging Tubes
First off, let’s get one thing straight: not all tube seals are the same. A toothpaste tube seal works fine for a cosmetic, but medicine? You need something that keeps air, moisture, and even tiny contaminants out. Medicines like creams for eczema rely on the active ingredients not breaking down when exposed to oxygen, and oral syrups in tubes? They can get contaminated if water gets in. I’ve worked with a ton of brands that mix up tube types, and that’s half the problem. If you’re using a laminate tube (the most common for meds, since it’s flexible and lightweight) vs. a plastic extruded tube, the sealing method has to shift. We see this all the time: a small brand comes to us wanting to use the same crimping method for their oral pain reliever tube as they did for their face cream, and it leaks. So first rule: match your sealing process to your tube material.
Let’s talk about the actual sealing methods we use here. The two big ones for medicine tubes are heat crimp sealing and ultrasonic sealing, and I’m not here to tell you one’s better for every job—because it’s not. Ultrasonic sealing uses high-frequency vibrations to melt the plastic layers of the tube’s neck together, and it’s perfect for tubes made of single-layer plastic or thin laminates that need a super tight, even seal. We use this a lot for liquid meds in tubes, like oral drops, because it doesn’t leave extra material that could flake off into the product. Heat crimp sealing, on the other hand, uses heated jaws to fold and seal the tube’s crimp end. It’s great for thicker laminates that have a metal layer (like aluminum foil, which is common for UV-sensitive meds) because the heat bonds the metal and plastic layers properly. But here’s the catch with both: you can’t just set it and forget it. We run test seals every single day, not just when we switch jobs. Last month, one of our ultrasonic machines had a tiny calibration issue that made the seals slightly weak—we caught it right away because we test 10 tubes per run, and avoided sending out a bad batch.
Now, let’s get into the small stuff that most people overlook, and it’s the stuff that makes all the difference. First: the tube’s neck prep. Before you even think about sealing, that open end of the tube has to be clean. If there’s leftover product on the rim, or dust from the factory, or even a tiny burr from cutting the tube, the seal won’t stick. I’ve had a client send us tubes that they pre-cut themselves, and half of them had little plastic shavings on the neck—their seals leaked, and they thought our equipment was bad. Nope, it was their prep step. We always blow the inside and outside of the tube neck with filtered air before sealing, and that’s non-negotiable. No shortcuts there.
Then there’s the crimp profile. Wait, what’s that? It’s the shape of the jaws that fold and seal the tube. For medicine tubes, you don’t want a flat crimp—you want a double or even triple crimp, depending on the tube size. A single crimp might work for a hair gel, but for a medicine tube, it’s too thin. I learned this early on when we started supplying tubes to a diabetes medication brand. Their first order had single crimps, and when they tested for leakage after shipping, 2% of the tubes had broken seals. We switched to a double crimp, and that number dropped to 0%. Why? Because the extra fold creates more surface area for the seal to hold, and it’s less likely to split during handling or shipping. Also, don’t forget to align the tube perfectly with the crimp jaws. If the neck is off-center, one side of the crimp is thinner, and that’s where leaks happen. We use small alignment guides on our machines now—something we picked up after a similar mistake—and it’s cut our seal failure rate by almost 15%.
Another big one: temperature and pressure control. With heat crimping, if the jaws are too cold, the plastic doesn’t melt enough to bond; too hot, and it melts through the tube, leaving holes or weak spots. With ultrasonic sealing, if the vibration frequency is off, the layers don’t melt evenly. We calibrate our machines daily, but we also adjust for different tube batches. For example, a batch of tubes made with 30% plastic vs. 50% plastic needs a slightly different heat setting. I used to think “one size fits all” would save time, but it doesn’t—when a seal fails, it costs way more than the extra 5 minutes to adjust settings for a new batch. We also use pressure sensors on every sealing machine now. If the pressure is too low, the jaws don’t clamp tight enough; too high, and you’ll deform the tube neck, making it hard to put the cap on later and breaking the seal. Sensors catch that in real time, so we don’t have to waste time checking every single tube.
Wait, and don’t forget about compatibility with the product inside. This is a huge one that not every packaging supplier talks about. Some medicines are acidic, or have solvents that can break down the seal material over time. We’ve had a client with a topical antibiotic that’s acidic, and their initial seal was made with a plastic that reacted to the medicine—after 2 weeks, the seal started to separate. We switched them to a laminate with a special barrier layer resistant to acidic meds, and the seals stayed perfect. So before you seal anything, test the seal material against your product for compatibility. I always tell clients: if you’re using a new medicine, run a 30-day test. Seal a few tubes, fill them with your product, and check the seal every week. Don’t just do a 24-hour test—that’s too short. We once had a client that skipped the long test, and their product started leaking after 2 months on store shelves. They had to recall 10,000 tubes, and it was all because the seal material wasn’t compatible.
Also, post-seal testing is non-negotiable. I don’t care how good your machine is, you have to test every batch. We do three types of tests here at our facility. First, a visual check: we look for any gaps, wrinkles, or uneven crimps. Any tube that doesn’t pass visual gets pulled. Second, a pressure test: we inject a small amount of air into the tube and check if the seal holds. If air escapes, that’s a bad seal. Third, a leak test by submersion: we put the sealed tubes into a tub of water, gently squeeze them, and look for bubbles coming from the seal. Bubbles mean a leak, so those tubes get discarded. Last quarter, we tested 50,000 tubes and only 0.3% failed—because we do these tests. I’ve seen other suppliers skip post-seal testing to save time, but that’s a risky play, especially for medicine. Your customers (and the people using the meds) trust that the product is safe, and a bad seal breaks that trust.
Now, let’s talk about common mistakes we see brands make when they’re sealing their own tubes, too. A lot of small brands will buy a cheap tabletop sealing machine, thinking it’s the same as the industrial ones we use. But tabletop machines don’t have the calibration or pressure control that industrial ones do. We had a new client that bought a $200 tabletop crimp machine for their natural pain reliever tubes, and their seal failure rate was 8%—way too high. They switched to using our in-house sealing service, and that rate dropped to less than 1%. So if you’re a small brand that can’t invest in a good sealing machine, don’t risk it—let a supplier like us handle it. We have the equipment, the testing, and the expertise to get it right.
Another mistake: over-tightening the cap after sealing. Wait, why does that matter? Because if the cap is too tight, it puts extra pressure on the seal, and if the seal isn’t strong enough, it can crack or split. We always advise clients to tighten the cap until it’s snug—no more. If you’re worried about leaks, the seal itself should be strong enough, not the cap. I’ve had a client that told me their team was tightening caps so hard some of the tube necks cracked. Once they slowed down and just tightened to a snug fit, their seal issues went away. It’s a small thing, but it adds up.
And don’t forget about storage before and after sealing. If you seal tubes and then store them in a hot, humid warehouse, that can break down the seal material. We recommend storing sealed tubes in a cool, dry place—under 25°C (77°F) and less than 50% humidity. We supply our tubes with small moisture-absorbent packets inside the boxes, and we tell clients not to stack heavy boxes on top of sealed tubes, because that can put pressure on the crimp and cause leaks. It’s all about the whole process, not just the sealing step.
Look, at the end of the day, sealing medicine tubes effectively is about more than just getting the product into a tube and closing it. It’s about protecting people. If a medicine is supposed to help someone feel better, a bad seal can turn that into a product that doesn’t work, or even makes someone sick. That’s why we take every step seriously here at our Medicines Packaging Tubes supplier—from checking the tube material to calibrating the machines to doing multiple tests on every batch.
Food Packaging Tubes If you’re a brand that’s struggling with seal issues, or you’re just starting out and want to make sure you’re doing it right, don’t hesitate to reach out. We’ve worked with everything from small startup meds to big pharma companies, and we can help you figure out the right sealing method for your specific product and tube type. No one-size-fits-all, no nonsense, just good packaging that keeps your medicine safe.
References
- FDA Guidance for Industry: Container Closure Systems for Packaging Human Drugs and Biologics, 1999.
- Handbook of Pharmaceutical Packaging Technology, 2nd Edition, CRC Press, 2015.
- International Society for Pharmaceutical Engineering (ISPE) Good Practice Guide: Packaging Operations, 2020.
- Pinner, E. et al., Seal Integrity Evaluation for Flexible Pharmaceutical Packaging, Journal of Pharmaceutical Sciences, Vol. 102, No. 8, 2013.
Yangzhou NewGreatWall Plastic Co., Ltd.
Yangzhou NewGreatWall Plastic Co., Ltd. is one of the most professional medicines packaging tubes manufacturers and suppliers in China, specialized in providing high quality custom service. We warmly welcome you to wholesale medicines packaging tubes for sale here from our factory. Contact us for quotation.
Address: No.12 Tongzhou Road, Hangji Industrial Park, Yangzhou, Jiangsu
E-mail: sales@ngwpack.com
WebSite: https://www.cosmeticplastictube.com/
