Bubbles can appear in a fresh coat of nail polish for many reasons, including improper application and excessive oil on the nail plate. Improper application techniques include using old polish, excessively shaking the bottle before application, applying thick coats and not allowing the polish to dry properly between coats.
If nail polish is applied in thick coats, the outermost portion of the polish dries quicker than the rest, which effectively traps evaporating solvents within the polish and causes bubbles. This same result occurs when secondary coats are applied over tacky polish, which has not dried completely. Additionally, hand lotions and oils can leave residue on the nail plate, causing bubbles to appear in the polish.