30 Vol developers will lift 2-4 levels using permanent hair colour. Lower level developers tend to take longer to process and don't offer as visible results. Stronger level developers increase the rate of reaction, but are also more likely to cause damage to the hair.
As a hair professional, it's important to understand your clients colour history and hair condition before undertaking any bleaching or colouring services on their hair. If hair is dry and brittle, it will be more susceptible to breakage and it's better to gradually colour the hair rather than try to lighten it too much or too quickly.
Developer or Peroxide?
The consistency of developer and peroxide differ. Peroxide is a substance that is a runnier liquid as opposed to the developer. A developer is better suited for carrying out a balayage colour and can help prevent colour leakage. This is due to the consistency being thicker and less likely to run, drip or bleed into other foils.
Both products are easy to work with and process in a similar time. It just comes down to personal preference and technique. If you have any questions about which is best for your needs, contact our friendly staff and we'll be happy to assist.