Which tool is commonly used for achieving tight curls?

The tool that is commonly used for achieving tight curls is the curling iron. Curling irons come in various barrel sizes, and those with smaller barrels are specifically designed to create tighter curls. When hair is wrapped around the heated barrel, the heat effectively reforms the hair's hydrogen bonds, allowing it to hold the shape of the curl. This method provides control over the size and tightness of the curls, making it a preferred choice for many hairstylists when clients request defined, tight curls.

The other tools mentioned serve different purposes. A round brush is typically used in conjunction with a blow dryer for styling, particularly for adding volume and creating soft waves, rather than tight curls. A flat iron is designed to straighten hair, but it can also create waves or curls depending on the technique used, though it is not as effective for tight curls compared to a curling iron. Finally, a blow dryer is primarily used for drying hair and can help in setting styles, but it does not create curls on its own without other tools. Therefore, for targeting tight curls specifically, the curling iron is the most effective tool.