What is the active ingredient in most depilatory creams?

The active ingredient in most depilatory creams is calcium thioglycolate. This compound works by breaking down the protein structure of the hair, effectively dissolving it so that it can be easily wiped away from the skin's surface. Calcium thioglycolate achieves this by utilizing a chemical reaction that weakens the hair's keratin, allowing for painless hair removal compared to other methods. This property makes it an essential ingredient in depilatories, which are designed for quick and efficient hair removal without the use of shaving or waxing.

In contrast, other options like calcium carbonate, sodium chloride, and potassium hydroxide do not serve the same functional role in hair removal. Calcium carbonate is primarily used as a bulking agent or pH adjuster, sodium chloride typically serves as a preservative or for enhancing texture rather than hair dissolution, and potassium hydroxide is more aggressive; while it can help with pH adjustment, it is not specifically effective for hair removal purposes. Thus, calcium thioglycolate stands out as the correct choice due to its targeted action in the formulation of depilatory creams.