A rotating flat iron is a hair styling device that combines elements of a brush, curling iron and flat iron. The devices are supposed to provide better results than a traditional flat iron and allow an increased number of styling options. They also are supposed to keep hair healthier, as they are said to "polish" the hair using a lower amount of heat compared to a regular flat iron.
Three major parts are on any rotating flat iron. The first is the cylinder, which is a rod-shaped section connected to the handle; some rotating flat irons are designed similarly to regular flat irons and have two cylinders that work together. The cylinder rotates while the iron is use, hence the name of the device. On some models, also connected to the handle via a hinge mechanism is a concave-shaped metal arm, which closes over the rotating cylinder when the hinge is closed. The third major part of the rotating flat iron is the bristles, which are connected to the inner sides of the metal arm or to the outside of the rotating cylinder(s).
A person typically uses a rotating flat iron for straightening hair. For this purpose, the user selects a small portion of hair one to three inches (2.5 to 7.6 cm) wide. Starting near the scalp, the user puts the hair between the cylinder and metal arm. She then slides the tool down the length of the hair, keeping tension but not pulling as she goes.
Even though the major purpose of a rotating flat iron is to straighten hair, this tool also can be used to create curls and waves. To do this, the user simply wraps her hair around the cylinder portion of the instrument. The size of the curls is limited by the size of the cylinder, but factors such as how tightly the user wraps the hair also matter.
During use, the brushes of a rotating flat iron both separate the hair strands and provide body. They keep the hair from being pressed absolutely flat, which is what happens with a regular flat iron. Manufacturers typically focus on the cylinder as the "miracle" part of the tool, however. As the cylinder rotates, it helps smooth the individual protein scales of the outermost or cuticle layer of the hair strand. This means the hair has better protection against the environment, reflects light better and looks shinier, and is better able to regulate moisture.
The way the cylinder, metal arm and brushes of a rotating flat iron work mean that it isn't usually necessary to use a lot of heat to get good results. This is important because some heat-based styling tools can reach up to 400 degrees Fahrenheit (204 degrees Celsius), which quickly saps necessary moisture from the hair and results in brittle strands. To accommodate the physical differences in different hair types, however, most rotating flat irons are equipped with several distinct heat settings.