Heat DialHair tools judged by heat and watts

Hair care and beauty devices

Reactions and irritation

Reactions, patch testing and when to stop.

1 guides

A hand drawing a black flat-plate straightener down a long section of straight brown hair — One slow pass with narrow plates is how a straightener is meant to be worked through a section.Photo: Leomedia · CC0 · Wikimedia Commons · Open source page

A hand drawing a black flat-plate straightener down a long section of straight brown hair

Reactions and irritation

Heat, fumes and irritation: the three risks that have published numbers

Formaldehyde released from heated smoothing products, exposure limits in parts per million, and the plug device that exists because dryers end up in water.

Updated 11/3/2026 · 8 min

Photo: Leomedia · CC0 · Wikimedia Commons