Permanent waving and hair straightening

The document reviewed the evolution of permanent waving and hair straightening techniques, highlighting the significant shift in the 1940s with the introduction of thioglycolate waving lotions, which allowed for room temperature processing and reduced time and danger compared to earlier methods using alkali and heat. Despite the emergence of bisulfites and cysteine in specialized contexts, thioglycolate lotions remained the most popular method nearly 50 years later. The chapter aimed to provide an overview of contemporary practices and interpretations of research data and commercial formulations rather than a comprehensive historical review.