Metal and Teflon devices harm hair the most. When exposed to high temperature, the metal releases positive ions, which lead to loss of moisture, brittleness and drying of the hair.
The curling iron with a ceramic coating practically does not harm the hair. It distributes heat well, which allows you to "close" the hair scales. Due to this, the internal moisture of the hair is not lost.
It is better to purchase a device made entirely of ceramic - in which case it will last longer.
The tourmaline coating is a dust of tourmaline crystals - a semiprecious stone, which heals the hair when heated, gives it softness and shine. Tourmaline does not wear off over time, unlike ceramics and teflon. Its only negative is the high price.
The titanium coating does not dry out and does not electrify the hair, heats them evenly and produces negatively charged ions.
Titanium-coated curling irons heat up quickly and can be used on any hair (even thin and weak).
A screen with temperature digits is the easiest and most understandable way to track the degree of heating of the styler.