Brushing and detangling

Key takeaways

• Most combing damage comes from tangles, not the comb itself. Hairs loop around each other and snap under sudden impact loads when a comb or brush drives through a knot. Robbins 2006 Robbins 2006 II Kamath 2011 Less tangling means less breakage.
• Conditioner is the biggest lever with evidence. It reduced short and long breaks in tress tests Robbins 2007 and cut the chance of a damaging snag on wet bleached hair from 100% to under 10%. New 2018
• Wet versus dry combing is a trade-off. Dry combing breaks the ends more with every stroke; wet combing breaks hair higher up, because water raises friction and lowers the load the fibre can take. Robbins 2007 Hair type changes the answer: wet combing raised snag frequency in straight Caucasian hair (0.47 versus 0.2 dry) but lowered it in Asian hair (0.1 versus 0.2). New 2018
• Curly and coily hair should be detangled damp or wet, with conditioner, never dry. Williams 2025 Dry-combing tightly curled hair is a classic cause of acquired trichorrhexis nodosa, a breakage disorder. Haskin 2017
• Brushes break more hair than combs. Brushing produced the largest shift toward long breaks of any condition tested. Robbins 2007 IV Use a wide-tooth comb or flexible-bristle brush to detangle, and keep styling brushes for hair that is already detangled.
• Start at the ends and work up in short strokes. Physics backs this: short strokes from the free end move tangles off the hair rather than tightening them. Plumb-Reyes 2022
• "100 strokes a day" is a myth that can hurt. Cuticle damage grew linearly with combing strokes on Afro hair, and 480 strokes did more cuticle damage than frequent braiding. Molamodi 2021 The average woman surveyed combed only about 16 strokes a day. New 2018
• Boar-bristle brushes may "spread sebum", but that has never been measured. Williams 2025

The science

Tress studies show two breakage pathways.

• Short breaks (under 2.5 cm) at the tips come from tips whipping around comb teeth or each other. In dry combing they increase with every stroke, and are worse with a blunt cut than a tapered one. Robbins 2007
• Long breaks (over 2.5 cm) mid-shaft come from impact loading of looped, crossed hairs. They increase with bleaching, longer strokes, curlier fibres, wet combing and especially brushing. Robbins 2007 IV

How much force real combing applies: researchers fitted single fibres to a load cell inside tresses and surveyed 231 women. Women combed about 16 strokes a day. Fibres rarely felt loads of 1 g or more (probability 0.2 in dry combing). Wet bleached hair snagged every time, and conditioner cut that to under 0.1. Damage concentrates where hair is wet, bleached and unconditioned. New 2018

Curly and coily hair: in a 2005 industry survey, 96% of African-American women reported breakage. No structural or chemical difference fully explains the higher breakage of tightly curled hair, and grooming practices are the main suspect. McMichael 2007 Split ends form when hair is cycled through tangle-like loops, and in bleached or low-quality hair splits start inside the fibre and run a long way. Taylor 2024 The cuticle becomes more fragile from the 40s and 50s. Takahashi 2015

Acquired trichorrhexis nodosa is a common cause of breakage at every age, especially in tightly curled hair, and is managed with a gentler routine and appropriate cleansers and conditioners rather than drugs. Haskin 2017 Geisler 2024

A 2025 dermatology guide describes ten brush types and notes that misuse can cause breakage disorders and traction alopecia, while guidelines matching brushes to hair types are lacking. Its advice is expert opinion, and no comparative trials of brush types exist. Williams 2025

What it means by hair profile

• Straight, fine hair: detangle gently with a flexible-bristle brush or wide-tooth comb and avoid brushing while dripping.
• Wavy hair: detangle in the shower with conditioner in; dry brushing breaks up waves and creates frizz.
• Curly and coily hair: detangle only wet or damp with plenty of conditioner, in sections, from the ends up, with fingers or a wide-tooth comb first. Never dry-brush.
• Bleached, relaxed or high-porosity hair is most fragile when wet; always condition before combing.
• Long hair: use shorter strokes from the ends.
• Thinning hair: shedding 50-100 hairs a day is normal. Tight brushing into slick styles can add traction.
• Age 40 and over: gentler tools and more conditioning are reasonable.

Myths and facts

• Brush 100 strokes a day for shiny hair: myth; more strokes means more damage.
• Never comb wet hair: oversimplified; curly hair should be combed wet with conditioner.
• Boar bristles spread your natural oils: untested.
• Start detangling from the roots: wrong; start at the ends.
• Detangling brushes cut breakage by a set percentage: the figures come from unpublished manufacturer tests.
• Combing makes hair fall out: mostly myth; the studies measure breakage, not root loss, though repeated tension can cause traction alopecia.

Practical recommendations

1. Condition first, then detangle, with rinse-out conditioner, a leave-in or a detangling spray.
2. Work from the ends up in short strokes, holding the hair above the section.
3. Use fingers first, then a wide-tooth comb or flexible detangling brush; use styling brushes only on detangled hair.
4. For curly and coily hair, detangle wet with conditioner in sections; never dry-brush.
5. Brush only as much as you need to style.
6. Trim damaged ends, since blunt, damaged tips catch and wrap more.
7. Budget: free (fingers and the conditioner you have), $ (wide-tooth comb), $-$$ (flexible-bristle brush). Premium brushes offer no proven advantage.

Related: hair drying, sleep and hair, traction and hairstyles, hair myths.

Bottom line

Conditioner plus gentle, end-first detangling beats any special brush. Discuss with a doctor.