Can you use 30 developer to get your hair a darker color?

Yes, you can use 30 volume developer to achieve a darker hair color, but it's not typically recommended. A 30 volume developer is primarily used for lifting hair color rather than depositing it. For darkening hair, a lower volume developer, such as 10 or 20 volume, is usually more appropriate to minimize damage and achieve a more controlled result. Always follow the instructions provided with your hair dye for the best outcomes.