Annie Humphreys is a tiny lady. Well under five feet tall. But her diminutive physical size is in direct opposition to her oversized influence on professional haircolor. Her work over a career that spanned almost 50 years with Vidal Sassoon impacted generation after generation of haircolorists—including a significant number of today’s most popular and important artists. In fact, one could say quite truthfully that Annie is the mother of modern haircolor.

Why? First, consider the color techniques and designs you admire—and most likely do everyday in the salon. Annie did them first. Foiling? “Annie was doing foil when…