Anyone with weak, brittle, peeling, or damaged natural nails caused by frequent hand-washing, cleaning products, or repeated polish/enhancement removal, who wants to rebuild nail strength from within rather than just coat the nail. Suitable for everyday consumers using it at home and for nail professionals using it as a pre-service prep step — it is a vegan, 9-free formula.

Its differentiator is that it's formulated to penetrate the nail and rebuild keratin bonds inside the nail plate, rather than sitting on the surface like a base coat or hardener, and its zero-dry-time, minimal-ingredient formula makes twice-daily use practical for both at-home nail care and as a professional prep step before polish or enhancements.

Apply one thin layer to clean, bare (polish-free) nails twice a day for six days for best results; zero dry time means it can be applied any time, including right before bed. As a professional pre-service prep step, apply two coats to all nails and wait 10 minutes before continuing with polish or enhancement application.

Pros:

• Minimal 4-ingredient, vegan, 9-free formula with zero dry time for flexible use anytime, including before bed
• Targets the nail plate itself (bond-building) rather than just sitting on top like a polish or hardener
• Doubles as a professional prep step before polish or enhancements, not just a standalone home treatment

Cons:

• Requires consistent twice-daily application for 6 days to see the brand's reported results — not a one-time fix
• Brand-reported performance figures are OPI's own marketing claims, not independently verified in this research
• Addresses existing nail damage rather than preventing new mechanical damage from continued exposure