Leaking Primary Packaging - Causes, Solutions, and Prevention

Causes:

Container and closure mismatch: there are so many standardised neck thread measurements, and matching them isn’t always as easy as it seems. While your best initial safeguard is – clearly – to use matching standard specifications for your container and closure, in practice it’s often tempting to go for slightly mis-matching ones, as often they will appear to fit. If you’re being dragged this direction, remember that it’ll be even more important than usual to thoroughly test your pack against all circumstances it might encounter.

Mis-matched H dimension: even with all the standardisation around containers and closure threads, it’s still possible to get a mis-match due to an adjustment in liner thickness (or another variable), causing an incomplete seal. Also, specifications that are on the edge – or just outside – of the stated standard, even when they initially appear to seal, can be a disaster if one of the components drifts to the other extreme of its allowable tolerance. Our team of packaging technologists is right here to do a desktop study on the tolerances of your chosen pack, before your pack starts going through the rigours of production and retailing or distribution.

Wrong liner/no liner: carefully selecting a closure with a suitable material and thickness of liner can make the difference between a great seal and no seal at all. And it doesn’t take much, very slight tweaks can make all the difference. Some liners may do a great job initially and then degenerate over time or due to ingredients in the product. Or, look at a boreseal, which has a flange which inserts into the bottle neck – if you pair it with a thick walled glass bottle, the diameter of the boreseal could be larger than the internal neck bore of the bottle, preventing the cap from screwing on properly. Liners and wads are there to seal the pack and are probably the most critical component to specify correctly, so just make sure you’ve got the right expertise allocated to this piece of specifying work!

Over-torquing: every closure has its own ideal torque, and it tends to be that the larger the closure, the higher the required torque – but over-do it and you could create a few other issues! Here’s our guide table to assist, though we want to make it clear that this is only a starting point, to help you on your way to finding the optimum through your own testing processes:

Filling processes: the old ‘back-off’ issue is the oddest thing, the first time you come across it – how did that closure just unscrew itself? The secret to stopping this lies in clean, accurate filling. Get a drip or two of product on the neck threads, especially an oily substance, and you create the chance of back-off, where the friction is reduced and the cap slightly unscrews back from the ideal torque.

Formulation incompatibility: Essential oils with certain plastics is one of the most common examples of when your formulation isn’t compatible with the container or closure. Even though they’re 100% natural, they can cause softening of the plastic, producing worrying results - even destroying liners, eroding threads, jamming pump mechanisms… and more!