.

Backcombing damage - Teasing hair overzealously can curl the cuticle scales back on themselves, exposing the cortex, causing permanent damage. For a brief moment in time the flat spots are filled in, but over time, too much can make the hair brittle and looking fried.

Virgin hair - this is hair that has never been chemically treated or exposed to blowdrying

Chemically damaged - Chemicals soften the cuticle so the product can penetrate. The scales then dry out, curl back on themselves and become raised. Simply brushing the hair can shave off those cuticle scales, exposing the inner cortex and making the hair vulnerable to breakage. Excessive and poorly executed chemical procedures can also cause the scales to fall off.

Steam blisters - Blowdrying hair using high heat can cause the surface to dry out very quickly, leaving the inner cortex still moist. The resulting trapped steam causes blisters to form in the cuticle. The hair looks dull because of its uneven texture and is prone to breaking off because of the blisters.