What is BIAB?

What makes BIAB different from regular gel polish

Standard gel polish sits on top of the nail as a colour coating. BIAB is a builder gel — it adds structural support to the natural nail as well as colour or a clear finish. This makes it more resistant to breaking and chipping, which is why it tends to last longer (typically 3–4 weeks versus 2–3 weeks for standard gel).

• —Stronger and more flexible than standard gel polish
• —Can be applied thicker to add length or reshape the nail
• —Does not contain the acrylics or monomers found in acrylic nails
• —Soaks off with acetone rather than being filed off
• —Suitable for thin or damaged nails that cannot tolerate acrylic

How BIAB appointments work

A BIAB infill (also called a fill or infill) is the maintenance appointment to keep the nails looking fresh. As the natural nail grows, a gap appears between the cuticle and the gel. At an infill appointment — typically every 3–4 weeks — the nail tech fills this gap, reshapes the nail, and refreshes the colour or finish.

Common BIAB appointment types and durations

Nail technicians typically offer BIAB across three appointment types. Knowing the typical duration matters for booking systems, because each requires a different amount of diary time.

• —BIAB Full Set — first application or complete removal and reapplication. Duration: 90–120 minutes.
• —BIAB Infill — fill-in of new growth, nail reshaping. Duration: 60–90 minutes.
• —BIAB Removal — soak-off and removal without reapplication. Duration: 30–45 minutes.

Patch testing for BIAB

Most BIAB products require a patch test 24–48 hours before the first appointment. This is standard practice for any gel or gel-adjacent product that contains potential allergens. Nail technicians typically manage patch test requirements as part of their booking process — clients who have not had a patch test should be identified before their appointment to avoid cancellation on the day.

Why nail technicians need specialised booking software for BIAB

BIAB appointments vary significantly in duration. A standard gel polish appointment might be 45 minutes; a BIAB full set can be 2 hours. Booking software that does not account for service-specific durations will either block too little time (leading to scheduling clashes) or too much time (leaving gaps in the diary). Nextro allows nail technicians to set individual durations per service, so BIAB Full Set, BIAB Infill, and Gel Polish are treated differently in the available times shown to clients.