Boar bristles (Sus scrofa) used in hair brushes are natural keratinous fibers. Their structural similarity to human hair — α-keratin, cuticle, cortex — makes them mechanically compatible with the hair surface during brushing. Hairswiss analyzes the tribological mechanism, the chemistry of sebum distribution and ethical and environmental considerations.
Tribological mechanism: sebum distribution and friction
The fundamental action of boar bristles operates through a capillary and tribological mechanism. During brushing, the bristles adsorb sebum from the proximal portion of the hair shaft through capillary action between adjacent fibers, then progressively distribute it toward the distal ends. This redistribution of the natural lipid film — composed primarily of squalene (~12%), waxy esters (~25%), triglycerides (~41%) and free fatty acids (~16%) — lubricates the cuticle and reduces the difference in static charge between fibers. The friction coefficient of the cuticle surface decreases significantly after regular brushing, resulting in frizz reduction and increased specular reflectance (shine).
Structural compatibility with human hair
Boar bristles have a diameter of 50–80 μm, comparable to fine to medium human hair. Their surface displays micro-scales that interlock with the cuticle scales of the hair during brushing, producing a controlled mechanical polishing effect without localized stress concentration — unlike synthetic bristles (nylon, polyester) with often blunted ends and higher stiffness.
The boar bristle + nylon combination: the professional mixed formula
The highest-performing professional brushes combine boar bristles and synthetic bristles (nylon) in the same brush head. The logic is chemically grounded: the stiffer nylon tips mechanically detangle knots and separate fibers before the softer, chemically compatible boar bristles distribute sebum and polish the surface. This two-phase action produces superior results compared to either tool used alone, particularly on curly, colored or straightened hair.
Professional selection criteria
Not all boar bristle brushes are equal. Professionals should evaluate three parameters: bristle density (high density = greater sebum transfer per stroke, but higher mechanical load on fragile hair), bristle stiffness (firmer for thick, dense hair; softer for fine, damaged or chemically treated hair) and pad construction (cushioned rubber pads reduce transmission of excessive brushing forces to the scalp). Ionic pad models complement the tribological action by neutralizing electrostatic charges responsible for frizz.
Professional brush available on cliCHair
The Flexion (L) by Edelstein, available on cliCHair.ch, is designed precisely around this mixed combination: its boar and nylon bristles work in complementarity — the nylon tips detangle without breakage, the boar bristles distribute sebum and polish the cuticle. The flexible ionic pad improves pressure distribution on the scalp and reduces the electrostatic charges responsible for frizz. A concrete example of a brush whose architecture reproduces the mechanisms analyzed in this article.