How long should you typically leave a perm solution on the hair?

The typical time to leave a perm solution on the hair is usually around 15-20 minutes. This duration allows the solution to effectively penetrate the hair shaft and alter the hair's chemical structure, enabling it to take on the desired curl pattern. Leaving the solution on for too short a time may not provide enough processing to achieve the desired curls, while longer durations can potentially damage the hair or lead to unwanted results.

In this range, the solution interacts with the natural proteins in the hair, breaking and reforming the disulfide bonds that give hair its shape. Hair texture, condition, and thickness can affect how long the solution should remain, but the 15-20 minute window is a general guideline that balances effectiveness and safety for most hair types.