15 Best Hair Straighteners We’ve Tested (2023): Flat Irons, Hot Combs, and

A lot of hot hair tools, including most on our list, claim to release negative ions to protect your hair. I used to chalk this up to marketing-speak, but hairstylists I spoke with say ions are helpful.

London-based hairstylist Hollie Rose Clarke says ions in hair tools keep the cuticle layer of your hair smooth, so you’ll get a shinier, frizz-free result. “Think of a strand of your hair as being the size of my arm, covered in fish scales (the cuticles),” she says. “When the hair is damaged, they open slightly, resulting in dry, frizzy, and weak hair. When the hair is healthy they are closed, resulting in your hair feeling smoother and stronger.”

Abra McField, founder of Abra Kadabra Hair and Healing, says hair is usually positively charged due to its water content, and the negative ions these flat irons generate can help dissipate that water. “You get controlled application of the heat you are applying, and you are able to use only as much heat as you need to smooth and straighten your hair, which can prevent damage.”

Ionic hair dryers are similar, with some caveats. “If you have finer hair and you are wanting as much body and volume as possible, the ionic dryer may not be the best,” McField says. “So generally it’s best to get a dryer with an ionic option that can be turned on and off.”