My top coat isn't fully cured and feels sticky. What should I do?

 The recommended curing time is between 30 and 60 seconds. After the top coat is cured, it will leave a tacky layer (that sticky protective film), which is normal and does not affect the curing result. Simply wipe the surface with a cleanser or 75% alcohol, and it will become smooth and non-sticky. However, if it still feels sticky or soft after wiping, it might be because: the curing time was insufficient (you can cure for another 30 seconds), the top coat was applied too thickly, the light couldn't penetrate/the lamp's power is insufficient or the beads are aging / you used a no-wipe top coat but treated it as a regular one (or vice versa), the lamp beads are aging (check if the light has dimmed or if some beads are not lit).