What happens when toning with a 30 developer?

When toning hair with a 30-volume developer, the process is more intense and can lead to significant color changes. The higher peroxide concentration lifts the hair's natural pigment more effectively, allowing the toner to deposit color more vibrantly. However, using a 30 developer can also increase the risk of damaging the hair, making it crucial to monitor the timing closely and follow up with proper conditioning treatments. It's generally recommended to use a lower volume developer for toning unless a specific, more dramatic effect is desired.