Which product category was NOT invented in the 1930s?

The correct response is plastic hair rollers, which were not invented in the 1930s. This is significant as the 1930s was a decade rich in innovation within the beauty industry, particularly with products aimed at enhancing hair styling and coloring.

Permanent hair color was a breakthrough at that time, enabling a more lasting solution for clients wanting to change their hair color effectively. Nail lacquer also emerged in the 1930s, evolving from earlier formulations to become the popular product we know today, providing a durable finish for manicures. The cold wave perm, a method of perming hair that did not require heat, was also introduced during this time, marking a shift in how perms were achieved.

In contrast, plastic hair rollers were developed earlier, with their inception dating back to the 1920s. They were part of the evolving beauty practices that enabled women to set their hair with ease and convenience, establishing their functionality well before the 1930s. Understanding the chronology of these developments can help situate the innovations within the beauty industry and highlight the technological progress that occurred during this transformative decade.