Documenting a client's service history (such as previous chemical treatments) is useful because:

Documenting a client's service history — especially previous chemical treatments like color, perms, relaxers, or keratin services — is useful because prior chemical work significantly affects how the hair will respond to a new service and the risk of damage (for example, layering incompatible chemicals can cause breakage). Knowing the history guides safe formulation, strand testing, and realistic expectations. Recording and reviewing service history is a professional practice that protects the client and supports good results, and it ties into the consultation content on the exam.