A few weeks after a fresh set of BIAB, you glance down and notice it: a neat little strip of bare nail between your cuticle and the gel. Nothing has gone wrong. Your nails are simply doing what they do and growing. This is exactly the moment a BIAB infill is designed for, and understanding how it works will help you keep your nails strong rather than starting from scratch every time.
What a BIAB infill actually is
An infill is a maintenance appointment. Rather than removing all of your BIAB and applying a brand-new set, your technician keeps the well-bonded product that is already there, files it down and refines it, then fills in the regrowth area with fresh gel. The result looks like a new set, but your natural nail has been spared a full removal.
That is the real appeal. Every full removal involves some filing and handling of the nail, so keeping a healthy base layer in place and only replacing what is needed is often the gentler option for people who wear BIAB long term.
Why regrowth matters more than you might think
When BIAB is first applied, your technician builds a slight curve, called the apex, at the strongest point of the nail. As your nail grows, that curve gradually travels forwards towards the tip. Over time, the weight of the product shifts and the nail starts to act like a lever. That is when knocks are more likely to cause cracks, lifting or a break at the free edge.
An infill resets that balance. The apex is rebuilt in the right place, the length is tidied, and the nail is back to being structurally sound. So while regrowth can look like a cosmetic issue, it is really about strength.
What happens during an infill appointment
- A quick check. Your technician looks for any lifting, chips or damage and talks through what you would like, including any change of colour.
- Filing back. The existing BIAB is thinned down carefully, leaving a secure layer bonded to the nail.
- Preparing the regrowth. The new growth near the cuticle is prepped so the fresh gel can adhere well.
- Rebuilding. New BIAB is applied over the whole nail, with the apex placed back where it should be, then cured.
- Finishing. Colour or top coat goes on, the shape is refined and cuticle oil is applied.
Because the foundation is already there, an infill is often a smoother appointment than a first set, though timings vary from person to person.
How often should you have a BIAB infill?
As a general guide, many people book an infill every three to four weeks. There is no fixed rule, though, and the right gap for you depends on a few things:
- How quickly your nails grow. Faster growers will see regrowth sooner.
- Your length. Longer nails feel the shift in balance earlier than short ones.
- How you use your hands. Hands-on jobs, gardening or lots of cleaning put more stress on the free edge.
- Your colour. A sheer nude makes regrowth far less obvious than a bold red, so you may simply feel ready sooner with a darker shade.
A good sign that you are due is when the gap at the cuticle catches your eye, or the nails start to feel slightly top-heavy when you tap them.
When an infill is not the right choice
Sometimes your technician will recommend removal instead. That might be because the product has lifted across a large part of the nail, because moisture appears to have got underneath, or because you want a complete change, perhaps a break from enhancements altogether. If your nails feel sore, look discoloured underneath, or the skin around them is red or swollen, an infill should wait and it is worth seeing a pharmacist or GP first.
If removal is the better option, it should always be done properly in the salon. Our guide on why professional BIAB removal matters explains what can go wrong when it is peeled off at home.
Booking your next infill
The cost of an infill depends on how much regrowth there is, your length and whether you are adding colour or nail art, so your technician will confirm the price before starting. You can see our starting prices on the prices page. A handy habit is to book your next infill while your nails still look great, rather than waiting until something breaks. Our online booking is open around the clock, sends instant email confirmation and lets you cancel free of charge online up to two hours before.