Beyond the 1A-to-4C Scale
For decades, the hair care industry and the broader public have relied on the Walker classification system — a visual scale running from Type 1A (straight) through Type 4C (tight coils) — to describe and categorise hair. The system was originally developed as a consumer marketing tool. It was never designed for scientific precision, clinical application, or legal evidentiary standards.
CROWN Hair DNA replaces this subjective framework with an objective, multi-dimensional profile generated by the CROWN Diagnostic device. Where the Walker system captures a single dimension through visual observation, CROWN Hair DNA measures twelve or more distinct properties through hardware-verified sensor analysis — producing a comprehensive characterisation that is reproducible across operators, environments, and time.
Why Subjective Classification Fails
The limitations of visual hair classification are well documented. A single individual’s hair can be assigned different Walker types by different observers, by the same observer under different lighting conditions, or by the same observer on different days. The system does not account for fibre diameter, porosity, hydration, protein structure, chemical treatment history, or any property that requires instrumentation to detect.
For consumer purposes, this imprecision is tolerable. For research purposes, it is not.
The CROWN Discrimination Index requires a reliable way to characterise individuals’ hair properties so that discrimination experiences can be correlated with objective physical measurements. Self-reported hair type — “I have Type 3C hair” — introduces the same subjectivity that the CDI is designed to control for. If the measurement of hair properties is itself subjective, the entire analytical chain is compromised.
CROWN Hair DNA provides the objective anchor that makes the rest of CROWN’s research infrastructure credible.
The Twelve Dimensions
A CROWN Hair DNA profile captures a minimum of twelve measured properties, each derived from one or more of the Diagnostic’s four sensor modalities. Together, they constitute the most comprehensive characterisation of an individual hair sample available outside a dedicated research laboratory.
Fibre Diameter (mean, variance, and distribution). Measured by optical micro-imaging at 0.1 micrometer precision. Human hair ranges from approximately 40 to 120 micrometers in diameter, with significant variation both across populations and within individual scalps. The mean, variance, and distribution of fibre diameter provide a structural fingerprint that is far more informative than visual curl pattern alone.
Cross-Section Ellipticity Index. Measured by optical micro-imaging. Hair fibres are not circular in cross-section — they are elliptical. The degree of ellipticity (the ratio of the major to minor axis) correlates with curl pattern: more elliptical fibres tend to curl more tightly. Unlike visual curl assessment, the ellipticity index is a continuous, quantitative measurement that captures the full spectrum of hair geometry.
Cuticle Layer Count and Condition Score. Measured by optical micro-imaging. The cuticle — the outermost layer of the hair shaft — consists of overlapping scales whose number, arrangement, and integrity determine how hair interacts with moisture, light, and mechanical stress. Cuticle damage from chemical treatment, heat styling, or environmental exposure is objectively measurable and clinically significant.
Curl Pattern Classification (Objective, Sensor-Verified). Derived from optical imaging and AI classification. CROWN Hair DNA does produce a curl pattern classification, but it is derived from measured structural properties (fibre diameter, ellipticity, torsion) rather than visual assessment. The result is reproducible and consistent — the same hair sample produces the same classification regardless of observer, lighting, or styling.
Porosity Index. Measured by impedance sensing. Quantifies the degree to which the hair cuticle permits moisture transfer. Porosity affects everything from product absorption to drying time to breakage susceptibility. CROWN’s impedance-based measurement replaces the subjective tactile assessment (“rough means high porosity”) that currently prevails.
Hydration Level. Measured by near-infrared spectroscopy. The water content of hair — both bound water within the cortex and surface moisture — affects mechanical properties, styling behaviour, and damage susceptibility. NIR spectroscopy provides a non-destructive quantitative measurement.
Protein Integrity Index. Measured by near-infrared spectroscopy. The structural integrity of keratin — specifically the disulfide bonds that maintain the protein’s three-dimensional configuration — determines hair strength, elasticity, and resilience. Chemical straightening permanently disrupts these bonds, producing a measurable change in spectral signature.
Chemical Treatment History. Measured by near-infrared spectroscopy. The spectral signature of chemically treated hair differs measurably from untreated hair. CROWN Hair DNA records whether chemical treatment is detected, providing an objective data point for research on conformity pressure and its relationship to discrimination.
Scalp Health Indicators. Measured by optical micro-imaging of the proximal hair shaft and surrounding scalp area. Indicators include follicular density, sebum levels, and signs of traction stress — the latter being clinically significant for individuals whose hairstyling practices are influenced by discrimination avoidance.
Breakage Susceptibility Index. Derived from combined optical and impedance data. Integrates cuticle condition, porosity, and protein integrity into a composite score predicting mechanical fragility. This index has direct clinical relevance for practitioners advising individuals on hair care and is relevant to population-level research on the physical consequences of discriminatory appearance norms.
Environmental Damage Score. Derived from spectroscopic and optical data. Captures the cumulative effects of UV exposure, pollution, humidity, and thermal stress. Provides context for interpreting other measurements — a high-porosity score, for instance, has different implications depending on whether it results from chemical treatment or environmental exposure.
Additional Dimensions. As the CROWN Hair Commons grows and the AI classification engine develops, additional dimensions may be incorporated — including sebum composition analysis, mineral content detection, and temporal change tracking from longitudinal scanning.
Reproducibility and Standardisation
CROWN Hair DNA is designed for one property above all others: reproducibility. The same hair sample, measured by different CROWN Diagnostic units in different locations, must produce statistically equivalent profiles. This requirement drives every aspect of the system’s engineering — from sensor calibration protocols to AI model training to the quality assurance procedures that govern device deployment.
Without reproducibility, the data contributed to the CROWN Hair Commons loses its research value. Without standardisation, cross-site comparisons become unreliable. Without consistency, legal and regulatory applications become untenable.
This commitment to measurement rigour is what distinguishes a research classification system from a marketing tool. The Walker scale was designed to help consumers choose products. CROWN Hair DNA is designed to produce data that can withstand the scrutiny of peer review, regulatory evaluation, and courtroom cross-examination.
Applications
CROWN Hair DNA profiles serve multiple functions within CROWN’s integrated research ecosystem:
Individual. Each person scanned receives their own CROWN Hair DNA profile — a comprehensive understanding of their hair’s properties, condition, and needs. This profile can inform personalised care recommendations and serve as a baseline for longitudinal tracking.
Research. Anonymised profiles, aggregated in the CROWN Hair Commons, enable population-level studies on hair property distribution, the prevalence of chemical treatment, and the correlation between objective hair characteristics and discrimination experiences.
Clinical. Practitioners delivering CROWN’s 360° Integrative Mind-Body Therapeutic Protocol can use CROWN Hair DNA data to understand the physical dimensions of a client’s experience — including whether chemical treatment patterns suggest conformity pressure.
Legal. Objective, hardware-verified hair characterisation provides a foundation for evidence-based legislative standards. If legislation protects natural hair, CROWN Hair DNA can objectively establish what constitutes an individual’s natural hair properties — a determination that is currently left to subjective assessment.
The Standard We Are Building
CROWN Hair DNA is not merely a product feature. It is an attempt to establish a new measurement standard for a domain that has never had one. Just as the Fitzpatrick scale provided dermatology with a reproducible framework for classifying skin phototypes — enabling decades of subsequent research, clinical protocols, and regulatory standards — CROWN Hair DNA aims to provide the science of hair with an equally rigorous foundation.
The ambition is proportional to the gap. Today, no standardised, objective, multi-dimensional hair classification system exists anywhere in the world. CROWN is building one.