What it is and why it's in the formula
Mineral oil is a refined, fragrance-free carrier oil used across cosmetics for its ability to sit lightly on skin and nail surfaces without leaving a heavy film. In this formula it acts mainly as a base that helps the plant oils, vitamin E, and lighter actives disperse evenly through the fine mist, so every spray delivers a consistent, thin layer rather than a few concentrated drops. It's also part of why the finish is described as fast-absorbing rather than greasy.
Where it fits in the full formula
Mineral Oil is one of 16 ingredients disclosed openly on the PureNail Pro label — none of the formula sits behind vague "proprietary blend" wording. You can see the complete breakdown, including which oils pair with it, on the full ingredients page.