This book was born with a dual purpose. The first is to provide the hairstylist a suitable tool to deal with the problems they encounter in their daily work. I am sure many times it just happened to have an inventory shortage or even to find ourselves out of stocks in the warehouse, and we had to remedy with resourcefulness and tricks acquired from the experience accumulated over the years in our profession. The second purpose is to provide a real teaching tool for all those who come to this world of theory, practice, and lots of creativity. Getting familiar with the issues of colorimetry and apply them with satisfactory results, is not easy. Contents of the book: - 1.0 Biology - 2.0 Chemistry - 3.0 Tricho-chemistry - 4.0 Tricho-care - 5.0 Chemicals to avoid - 6.o Applied colorimetry - 7.0 Conceptual maps - 8.0 Glossary - 9.0 l ndex - 10.0 References - 57 Figures - 18 Conceptual maps - 7 Form ulas - 7 Charts - 7 Tests and verifications