Nails grow about three millimetres a month. That sounds like nothing until you look at an extension four weeks in: the gel has travelled up the finger, there is a visible step at the cuticle, and the balance point of the nail is now in the wrong place.
A refill is not a cosmetic touch-up. It is a structural correction, and the timing matters more than most people realise.
What actually changes as it grows
When we build an extension, the thickest point — the apex — sits about a third of the way up the nail. That is where the strength is, and it is positioned to take the load of everything you do with your hands.
As the nail grows, the apex moves forward with it. By week four it is no longer over the stress point, it is out past it. The nail is now front-heavy, which is exactly the condition that causes breaks and cracks at the sidewalls.
A refill fills the gap at the cuticle and, more importantly, files the old apex down and rebuilds it in the right place. That second part is why a refill takes an hour and not fifteen minutes.
The window
- Weeks 2 to 3: ideal. Minimal regrowth, quick appointment, no risk.
- Week 4: still fine for most people, especially with slower growth.
- Week 5: the gap is large, the balance is off, and lifting has usually started.
- Week 6 and beyond: often a full removal and a new set instead of a refill.
Nail growth is not the same for everyone. It speeds up in summer, slows in winter, and varies with age. If you consistently need a refill at week two, book at two — there is nothing wrong with your nails.
Signs you have left it too long
- A visible ridge or step where the gel starts.
- A white or shadowed line under the gel near the cuticle — that is separation.
- Nails catching on hair or fabric at the free edge.
- One or two nails cracking at the sides.
- The set feels heavy or top-loaded when you type.
Why late refills cost more
At three weeks we file back, fill the gap, rebuild the apex and re-cure. It is an hour and it is charged as a refill.
At six weeks, with lifting across several nails, there is nothing safe to build onto. The whole set has to be removed, the natural nail assessed, and a new set built from scratch — two hours or more, priced as a new set. Skipping two refills does not save money.
“Almost nobody books their refill late on purpose. They book it late because they did not book it at all when they left. Take the appointment before you walk out.”
Making a set last between refills
- Cuticle oil daily. Flexible gel lifts less than dry, brittle gel.
- Gloves for cleaning products and washing up. Detergent breaks down the seal.
- Do not use your nails as tools — no opening cans, no scraping labels.
- Dry your hands properly, especially around the cuticle.
- If one nail lifts, come in and have that nail fixed. Do not wait for the rest.
How many refills before a new set
Three or four refills is typical before the structure is worth rebuilding. A curved set needs more care here, because each refill leaves a small amount of older product behind, and over time the nail gets slightly heavier and the shape drifts from the original.
We will tell you when a set is due to be replaced rather than refilled again. It is usually obvious from the shape, and it is worth doing — a fresh build every three or four months keeps the nails lighter and the natural nail healthier.
If you are not sure where your set is in that cycle, send us a photo of your nails in daylight. We can usually tell from a picture whether you need a refill, a repair on one nail, or a full rebuild.