Menstrual cups work on a completely different principle than pads or tampons — they don't absorb anything. Understanding how a vacuum seal actually holds fluid in explains why sizing, insertion technique, and the learning curve all matter more than they do with disposable products.
How a Menstrual Cup Actually Holds Fluid In
A tampon or pad absorbs menstrual fluid into fibres. A cup does the opposite: once folded and inserted, it opens up inside the vaginal canal and forms a vacuum seal against the walls, collecting fluid inside the cup itself rather than soaking it up. That seal is what prevents leaks — not the material, not the shape on its own, but the airtight fit against the tissue. Get the seal wrong and the cup can leak even if it's the "right" size on paper.
Why Size Isn't Just About Body Size
Cup sizing is often assumed to track age or body size the way clothing does, but it actually tracks two different things: flow volume and pelvic floor firmness. A smaller, lower-capacity cup — like Minerva XS at 18ml — suits younger users, lighter flow, and those who haven't given birth, where a more compact size sits comfortably and the vacuum seal forms more easily. A larger-capacity set like Minerva S+L (23ml and 30ml) is built for medium-to-heavy flow, letting you switch between the two sizes as your flow changes across the days of a single cycle rather than settling for one size that's sometimes too much and sometimes not enough.
The Learning Curve Is Real — and Normal
Getting a reliable seal on the first try is uncommon. Most people need to experiment with different folds, and it commonly takes up to three cycles before insertion and removal start to feel automatic. That adjustment period isn't a sign that the cup is the wrong size or that something's wrong with you — it's simply how long it takes most people to learn the technique, and it's worth expecting rather than giving up after one difficult cycle.
What Actually Changes When You Switch From Disposables
The most immediate difference is wear time: a properly sealed cup can be worn safely for up to 12 hours, compared to the more frequent changes disposables require. The second difference is what happens over years rather than days — a medical-grade silicone cup lasts 5 to 10 years with proper care, which means buying and discarding far fewer products over that time, both a cost and a waste reduction that only shows up once you look past a single cycle. There are limits worth knowing: cups aren't recommended during penetrative sex, and IUD users should be cautious, since removal can occasionally disturb the IUD's position.
Practical Basics
Sterilise the cup by boiling it for around 5 minutes before first use, and again between cycles. Water or a water-based lubricant makes insertion easier while you're still learning your fold. Wash hands before inserting or removing, empty and rinse roughly every 12 hours, and store the clean, dry cup in its cotton bag between cycles rather than in an airtight container.
You can find the CRUSHIOUS Minerva S+L set and the CRUSHIOUS Minerva XS in our full collection.
