If you have spent any time on nail TikTok or Instagram lately, you will have seen the term BIAB everywhere. BIAB stands for builder in a bottle, and it is one of the most searched nail services in the UK right now. But here is the thing: BIAB is simply a type of builder gel that comes in a bottle rather than a pot. Once you understand builder gel, you understand BIAB.
I have spent over 18 months developing my own builder in a bottle, Sculptify, and in this guide, I am going to explain exactly what builder gel is, who it is for, and how to apply it step by step for a flawless, long-lasting finish.
Watch the full application video below, then read on for the detailed breakdown.
Sculptify: Kirsty Meakin’s Builder in a Bottle Soft Gel
Builder gel is a thicker-viscosity gel designed to add strength and structure to the nail. Unlike regular gel polish, which is purely cosmetic, builder gel reinforces the natural nail so it can grow longer without breaking, peeling or flaking.
You can use builder gel:
BIAB, or builder in a bottle, is builder gel housed in a polish-style bottle with a brush, rather than a pot you dip into with a separate gel brush. The formula self-levels beautifully and applies more like a polish, which makes it faster to work with and much more approachable if you are newer to builder products.
Sculptify is my builder in a bottle. It is a soak-off soft gel, which means when your client is ready for removal or a fresh set, it soaks off rather than needing to be filed away like hard gel. It took over 18 months of development to get the formula exactly right, and the result is a builder that self-levels so smoothly you will barely need to file after curing.
| Sculptify (BIAB / builder in a bottle) | Hard Gel | Gel Polish | |
| Removal | Soaks off | File off only | Soaks off |
| Strength | Strong with natural flex | Very rigid | Cosmetic only |
| Best for | Natural nail overlays, short to medium extensions | Long sculpted extensions | Colour and shine |
| Application | Bottle and brush, self levelling | Pot and gel brush | Bottle and brush |
Here is exactly how I apply Sculptify, whether you are a nail tech or doing your own nails at home. In the video, I am working on a silicone practice hand, which is a brilliant way to perfect your application before working on clients. If you want an even more detailed technical breakdown, we have a full step by step Sculptify application guide on the site too.
Good prep is everything. Push the cuticles back and make sure there is no non-living tissue left on the nail plate. Use the rounded end of your cuticle tool for the cuticle area and the straight edge to come down the sidewalls.
Shape the free edge with a 240-grit file. If you are applying over a tip, always file the top surface of the tip first. Gel will not bond to a shiny surface, and if you skip this step, you are inviting lifting.
Gently buff the entire nail with a 240-grit file or a sanding band on your e-file to remove the surface shine. Do not press hard, especially near the cuticle area. That part of the nail is freshly keratinised; it is still developing, so treat it gently and just skip lightly over the surface.
Turn your file over to get into the nooks and crannies around the cuticle. This is the area most people miss because they are nervous about getting too close, and it is exactly where lifting starts.
Dust off thoroughly. You will never spot a missed shiny patch until the dust is gone.
Wipe over with cleanser solution. This does two jobs at once: it cleans the nail plate and dehydrates it ready for product. There is no need for a separate dehydrator or primer with this system. I have tested Sculptify with and without primer, and it performs exactly the same, so save yourself a step and a product.
Base coat is essentially your primer here. Apply it super thin. Splay the brush slightly as you work, which spreads the product wider and thinner, and make sure you cap the free edge.
Here is the test of a perfect base coat application: you should still be able to see the texture of the nail coming through. Thin is the goal. Cure for 30 seconds.
This is the technique that makes builder in a bottle application so much easier, and most people skip it.
Take a small bead of Sculptify and spread a super thin layer over the whole nail, capping the edge. Do not cure it. This is your slip layer, and it works because of one simple rule: wherever gel has been, gel will go.
Pull a bead of product up one side of the bottle neck, then transfer it onto the nail. Spin the brush clockwise and anticlockwise to release the product, then sweep it from side to side, working down about 80 percent of the centre of the nail.
Do not stress about pushing the product right to the sidewalls. Because your slip layer is already there, the gel will naturally flow and settle into those areas on its own. If you need to encourage it, just tickle the very top of the surface with a fine liner brush. You are using the surface tension, not dragging through the product.
Check the nail from the side profile. Any bulk? Tickle it down. The self-levelling on this formula does most of the work for you, so you get a smooth, wiggle-free finish straight out of the lamp.
Cure for 1 minute. Base coat is 30 seconds, but your builder layer needs the full minute.
After curing, wipe over with a lint-free wipe to remove the sticky layer, then look at the nail. If it is shiny, you are fully cured. If it has gone matte, it is under-cured, so get it straight back in the lamp.
This is also a brilliant way to test whether your lamp still has life in it. Lamp bulbs degrade over time, and ideally, you should be replacing your lamp around once a year depending on how busy you are. A matte wipe-down is your early warning sign.
Because the formula self-levels, you should barely need to file. A light buff over to perfect the surface is usually all it takes.
From here, you have two options. If you are adding gel polish colour, go in with your base coat first. If you are keeping it natural or wearing the builder shade on its own, apply your glossy top coat. For top coat, do not splay the brush. Float the product down the nail, cap the edge, smooth through and cure.
Here is something a lot of people get wrong about builder gel. Stronger does not mean more rigid.
A cured layer of Sculptify has a little bit of flex, and that is deliberate. Your natural nail changes shape as it grows, so the shape of the nail at the cuticle is different to the shape further down the nail plate. If your builder is too rigid, the natural nail will start peeling away from the product as it grows. A builder with the right amount of flex bounces with the natural nail, which is exactly what gives you great retention and a longer-lasting set.
So when you press on a Sculptify overlay and feel a slight give, that is not a weakness. That is the formula doing its job.
Builder gel is perfect for:
Is BIAB the same as builder gel?
BIAB is a type of builder gel that comes in a bottle rather than a pot. All BIAB is builder gel, but not all builder gel comes in a bottle. Sculptify is a soak-off builder in a bottle.
Do I need primer with builder gel?
Not with this system. Your cleanser dehydrates the nail and the base coat acts as your primer. I have tested it both ways and there is no difference in retention.
How long does builder gel last?
With proper prep and application, expect around three to four weeks of wear, growing out with your natural nail. The flex in the formula is what keeps it bonded as the nail grows and changes shape.
Can you do long nails with BIAB?
Soak-off builders are designed for natural overlays and short to medium extensions over tips. For very long sculpted nails, you want hard gel or acrylic.
How do you remove builder in a bottle?
Sculptify is a soak-off formula, so it removes the same way as gel polish: buff the shine off the top coat, then soak with acetone until the product breaks down. No aggressive filing needed. We have a full builder gel removal guide covering both soak-off and hard gel removal.
How do I know if my builder gel is fully cured?
Wipe the sticky layer off with a lint-free wipe. Shiny means cured; matte means it needs to go back in the lamp.
Sculptify is available now in a range of shades, including Rita, the gorgeous semi-sheer candy floss pink used in the video, named after my late Auntie Rita. Pair it with a brush from our nail brushes range for tickling the product into place, and you have everything you need for a professional builder gel service.
Shop the full Sculptify builder gel range on the site, and if you try it, come and let me know how you got on over on Instagram, TikTok or Facebook. If you struggle with anything, we are always here to help.
Returns:
nails@kirstymeakin.com
Kirsty Meakin,
42 Winpenny road,
Park House Industrial Estate,
Newcastle Under Lyme,
ST57RH
