Back when I first started doing nails, gel polish didn’t exist. Most manicures ended with me helping clients put their coats on or fixing smudges after they’d run their hands through their hair too soon. When gel polish arrived, it was revolutionary. Instantly dry, glossy, and long-lasting,  it completely changed how we worked.

In over 30 years in the industry, very few innovations have been as transformative. But the rise of builder gels has taken things even further, bridging the gap between natural nails and traditional enhancements.

Personally, I’ve always loved having nice nails, but mine are naturally weak, they don’t hold extensions and gel polish used to peel off within days. Builder in a Bottle™ (BIAB™) changed that. It gave me strength, structure, and flexibility without the heaviness of acrylic.

In my salon, we don’t do many full sets of extensions anymore. They’re time-consuming and less profitable per hour. Builder gels, on the other hand, have created a reliable, loyal client base. It’s become the foundation of our nail business.

What Is Builder Gel?

Builder gel is a thicker, more durable version of gel polish designed to reinforce natural nails or add structure. It’s made from oligomers and monomers that harden under UV or LED light, forming a flexible but strong coating.

Unlike traditional gels of the past, modern builder gels are self-levelling, soak-off, and designed to protect the natural nail rather than smother it. They distribute pressure evenly, reducing cracking and breakage, while giving a smooth, high-gloss finish that lasts for weeks.

Builder gels can be applied in pots (with a brush) or bottles, which is where BIAB™ comes in.

What Is BIAB™?

BIAB™ (Builder in a Bottle) is a trademarked product created by The Gel Bottle Inc. Only The Gel Bottle can legally use that name.

Many brands now make their own versions of builder gel in a bottle under different names, such as structure gel, builder base, or strength gel. For ease, I’ll refer to all of them as builder gels throughout this article, though I personally use The Gel Bottle’s BIAB™ system in my salon.

Gel Polish – The Lightweight Option

Gel polish is applied like regular polish but cured under a UV or LED lamp to form a flexible, chip-resistant layer. It’s ideal for those with naturally strong nails who want a thin, glossy, and lightweight finish that lasts up to three weeks.

The chemistry involves photo-initiators, which react with UV light to polymerise the gel, creating a tough but flexible coating. However, gel polish alone doesn’t add strength or structure to weak nails,  it simply seals the surface.

Builder Gel (BIAB) – Strength and Flexibility

Builder gels (including BIAB™) add a layer of structure and flexibility, ideal for reinforcing weak or peeling nails. Unlike traditional hard gels, most BIAB-style formulas are soak-off, meaning they can be removed safely with acetone rather than heavy filing.

They can also be infilled instead of completely removed each appointment, reducing long-term damage and allowing natural nails to grow.

The key difference is in how the product moves,  BIAB is more elastic, flexing with the nail rather than lifting or cracking. This makes it perfect for clients wanting durability without the weight of acrylics.

And yes, BIAB can be used to create short extensions using forms or tips. It just doesn’t offer quite the same structural strength as acrylic or hard gel, so it’s best for shorter, natural-looking lengths.

Acrylic vs Gel Extensions – What’s the Difference Really?

There’s a common misconception that acrylic extensions and gel extensions are completely different systems. Chemically speaking, both ultimately create an acrylic nail, they just use different chemical processes to reach that result.

• Liquid and powder acrylic (often called L&P or traditional acrylic) is made by mixing monomer liquid with polymer powder. The chemical reaction between the two creates polymer chains that harden through air-curing. It’s extremely strong and durable, but also rigid and less flexible.

• Gel extensions, on the other hand, start as a pre-mixed liquid that contains similar acrylic-based components but remains in gel form until it’s cured under a UV or LED lamp. The curing process creates the same type of cross-linked polymer structure meaning both end up forming an acrylic-based nail enhancement.

The main difference lies in how they cure, how they’re applied, and how they feel:

• Acrylic sets by chemical reaction (no lamp required) and tends to be harder.

• Gel sets by light curing and tends to be smoother and slightly more flexible.

Both systems require infills every 2–3 weeks and both can be sculpted, but gel extensions usually offer a lighter, more modern alternative with less odour and dust.

How BIAB Differs from Acrylic and Hard Gel

While BIAB is technically a type of builder gel, it’s formulated as a soak-off system. That means it can be dissolved in acetone instead of being filed off, making it far gentler for long-term use.

BIAB’s strength lies in its balance of flexibility and durability it reinforces natural nails and can even be used for short extensions, but it isn’t intended to replace heavy-duty acrylic work.

Where acrylic excels at structure and length, BIAB excels at health and consistency. It’s the perfect middle ground for clients who want strength and a salon-quality finish without the commitment of full enhancements.

Choosing the Right Option

• Gel Polish – Best for naturally strong nails and a thin, chip-resistant finish.

• Builder Gel / BIAB™ – Perfect for adding strength, repairing damage, and supporting natural nail growth.

• Gel Extensions – A modern alternative to acrylics, offering strength with more flexibility.

• Acrylic Extensions (Liquid & Powder) – The strongest option for length and sculpted structure, ideal for advanced designs.

A qualified nail technician should always assess the condition of your natural nails first — taking into account flexibility, lifestyle, and how much structure your nails need before recommending the right system.

How to Make Your Nails Last Longer

No matter what system you choose, hydration and maintenance are key to long-lasting results.
Use cuticle oil daily, wear gloves when cleaning, and avoid picking or peeling your product. Regular infills every 2–3 weeks keep the product balanced and your natural nails protected underneath.

Q: Is BIAB the same as builder gel?
A: BIAB™ is The Gel Bottle’s trademarked version of builder gel. Other brands produce similar products under different names, but only The Gel Bottle can use the BIAB™ name.

Q: Are gel extensions and acrylics the same thing?
A: Chemically, both create acrylic-based nail enhancements, but they cure differently. Liquid-and-powder acrylics harden through air exposure, while gels cure under UV or LED light. The result is similar in structure but different in flexibility and application.

Q: Can BIAB be used to make extensions?
A: Yes, BIAB can create short extensions using forms or tips, but it isn’t as strong as acrylic or hard gel. It’s best suited for overlays, repairs, and short, natural enhancements.

Q: Does BIAB damage your nails?
A: Not when applied and removed correctly. In fact, it often helps protect and grow the natural nail underneath because it can be infilled instead of soaked off every time.

Q: Why do some BIAB sets lift?
A: Lifting usually happens when the nail isn’t prepped properly or curing times aren’t followed precisely. Nail dehydration and incorrect base layers can also cause adhesion issues.

Q: What’s the healthiest option for natural nails?
A: Builder gels like BIAB are generally the best long-term choice. They offer strength and flexibility without the heavy filing required for traditional acrylic systems.

Final Thoughts

The world of nail technology has come a long way from basic polish and smudged finishes.
Whether you choose gel polish, builder gel, BIAB, or acrylic extensions, each system serves a purpose, the key is matching the right product to your nail type and lifestyle.

For many clients, BIAB has struck the perfect balance,  giving strength, beauty, and repeatable results without sacrificing the health of their natural nails.

If you’re unsure which is right for you, talk to a qualified nail technician who understands product chemistry and can guide you toward the system that will keep your nails strong, flexible, and looking their best.