Final answer:
The epilation method of using small metal tongs to remove hair by the root is known as tweezing or plucking. It's different from depilation, which only affects the surface hair and can be achieved through chemical means, such as with depilatories containing calcium thioglycolate.
Step-by-step explanation:
The epilation method described in the student's question is known as tweezing or plucking. This method involves using small metal tongs, commonly referred to as tweezers, to grip and pull out individual hairs from the root. Unlike depilation, which only removes hair from the surface, epilation removes the entire hair, including the part below the skin.
Chemical depilatories, another method mentioned, differ from tweezing as they involve a chemical reaction to break down the hair's structure, making it easy to wipe away from the skin surface. The active ingredients, like calcium thioglycolate, alter the hair by breaking the disulfide bonds in keratin. After the hair is chemically weakened, usually within 10 minutes, it can be removed, and skin pH is restored using conditioners.