Raw Cashmere Classing and Guard Hair Percentage Estimation

Pelage

Raw cashmere fleece harvested from Capra hircus laniger consists of a dual-coat structure, where secondary hair follicles produce the soft down.

Secondary hair follicles produce the ultra-fine, non-medullated undercoat down, which typically measures between 13.5 and 17.5 microns in mean fiber diameter. Primary follicles produce coarse, outer guard hair ranging from 30 to over 120 microns in diameter, characterized by a prominent central medulla and high flexural rigidity. Commercial classing of raw fleece begins with determining the proportion of these two distinct fiber populations in the raw grease fleece prior to mechanical dehairing.

The morphology of cashmere down differs fundamentally from guard hair at the cellular level. Cashmere down exhibits a thin cuticle scale layer with smooth scale margins, scale heights below 0.5 microns, and a scale frequency of 60 to 70 scales per millimeter along the fiber length. Guard hairs possess prominent, thick cuticle scales with serrated edges, a high medullation index often exceeding 80 percent of the fiber cross-sectional area, and high scale frequency.

These structural differences dictate both mechanical separation behavior during dehairing and the physical performance of the finished yarn.

Coarse outer hair presence above five tenths of one percent by weight compromises skin-contact softness and accelerates pilling in fine gauge knits.

The geographic origin of raw fleece directly influences the ratio of down to guard hair, as well as the absolute diameter of down fibers. Combed cashmere from Inner Mongolia and Mongolian provinces yields a higher proportion of fine down relative to guard hair compared to clipped fleece from Middle Eastern sources, which contains cut guard hair ends and short fiber fragments that complicate mechanical separation.

Morphological Distinction and Follicular Origins

Cuticular structure determines the friction coefficient of individual fibers during carding and drafting operations. Down fibers exhibit low surface friction due to shallow scale edges, allowing gentle mechanical alignment without excessive fiber breakage. Guard hair exhibits strong directional friction, which mechanical dehairing equipment exploits to throw coarse fibers out of the fiber stream via centrifugal force and differential airflow.

Intermediate fibers, often termed kemp or coarse down, represent a challenging boundary population. These fibers arise from primary follicles that have reduced activity or secondary follicles experiencing seasonal enlargement. Their presence confounds automated optical diameter measurements and requires specialized sorting criteria during raw classing.

Grease cashmere lots containing coarse hair fractions above sixty percent require multiple passes through dehairing machinery. Each additional mechanical pass degrades down length distribution by three to five percent while generating short fiber fly.

Sieve

Bales arriving at the primary sorting station contain variable proportions of dirt, grease, vegetable matter, and coarse outer hairs, with yield ultimately driven by dehairing machine settings.

Classing raw grease fleece involves evaluating scoured yield, mean fiber diameter of the down fraction, grease content, and the percentage by weight of coarse guard hair. Unwashed raw cashmere fleece contains between 15 and 45 percent non-fiber impurities including suint, sand, skin flakes, and natural wool grease. Because vegetable matter degrades carding wire, excessive contamination necessitates aggressive opening procedures that increase fiber breakage.

Mechanical dehairing isolates fine down from guard hair through a series of rotating fine-wire cylinders and stationary knives paired with air velocity chambers. The process relies on the physical mass differential between fine down and heavy medullated hair. Fine down remains attached to card wire clothing while rigid guard hair is thrown off by centrifugal momentum into waste collection hoppers.

• Grease Fleece Classification categorizes raw lots by harvesting method, distinguishing combed fleece with intact root ends from clipped fleece containing severed fiber bases.
• Scoured Yield Testing determines the mass fraction of clean down, clean coarse hair, and total impurities following standardized aqueous scouring at low temperature.
• Coarse Hair Fraction Mapping estimates the ratio of guard hair to total fiber mass before dehairing to set machine cylinder speeds and worker throughput targets.
• Vegetable Matter Indexing quantifies burr and straw contamination levels that require specialized mechanical burr-picking prior to fine carding.

While combing leaves root structures intact, clipping cuts coarse roots short. Clipped lots contain stubby hair segments that match the length of fine cashmere down, causing these short coarse pieces to enter the clean down stream during air separation.

Dirt and suint content in unwashed grease cashmere distorts initial weight measurements before mechanical separation begins.

Mechanical Separation Mechanics

Sorting accuracy in the bale room dictates the commercial success of the dehairing run. Workers grade raw bales by hand-pulling staple samples to evaluate down length, crimp density, color, and visual guard hair density. Bales with high coarse hair density receive longer dwell times in opening lines to loosen entangled locks before feeding onto carding cylinders.

Dehairing efficiency measures the percentage of guard hair removed relative to the total guard hair initially present in the grease fleece. Achieving a residual guard hair content below 0.2 percent by weight from a raw fleece containing 60 percent coarse hair requires up to six sequential dehairing stages. Excessive mechanical action reduces mean down length from 38 millimeters to below 28 millimeters, drastically lowering the commercial value of the dehaired lot.

High residual coarse hair counts in delivered dehaired lots often reflect seasonal climate variations that alter follicle root sheath thickness during harvesting.

Optics

Laboratory measurement of guard hair percentage relies on microscopic examination or automated image analysis of fiber profiles to distinguish coarse medullated fibers from fine cashmere down.

Quantifying residual guard hair in dehaired cashmere down demands strict adherence to analytical standards. Standard air-flow testing methods designed for wool top fail on dehaired cashmere because medullated guard hairs contain internal air voids that distort air permeability readings. Direct optical measurement remains the sole accepted approach for accurate guard hair estimation.

Which Optical Test Method Resolves Boundary Hair Counts?

The Optical Fibre Diameter Analyser captures digital images of individual fiber snippets suspended in a liquid medium or spread on a glass slide. Automated software measures fiber profile widths and flags fibers exceeding specified micron thresholds. Modern image analysis platforms distinguish medullated guard hair from solid down fibers by detecting internal light refraction differences caused by the central medullary canal.

Test results governed by ISO 17751-1 mandate a minimum specimen count of two thousand fiber snippets to reach statistical significance on guard hair percentages below one percent.

Standard Analytical Protocols and Fiber Diameter Analysis

ISO 17751-1 utilizes optical light microscopy to classify fibers based on diameter and cuticular morphology. Technicians count individual fibers across multiple fields of view, measuring diameters and recording medullation state. ISO 17751-2 employs Scanning Electron Microscopy to examine scale structure at higher magnification, resolving disputes over chemically treated or stretched fibers where scale height has been mechanically altered.

1. Cut representative core samples from ten locations within the dehaired cashmere bale to ensure batch uniformity.
2. Guillotine the clean fiber bundle into precisely 0.8 millimeter snippet lengths using a heavy-duty specimen cutter.
3. Disperse the snippets evenly in glycerine on a microscopic slide, placing a cover glass without trapping air bubbles.
4. Scan the slide under a calibrated projection microscope or automated optical analyzer at 500x magnification.
5. Log at least 2,000 individual fiber measurements, categorizing every fiber with a diameter exceeding 30 microns as coarse hair.
6. Calculate the guard hair percentage by mass using relative volume and density formulas for solid and medullated structures.

Manual light microscopy under ISO 137 requires human operators to verify cuticular scale boundaries, reducing operator bias through double-blind specimen counting protocols. Scanning electron microscopy serves as the final arbiter when coarse fibers fall into the 18 to 28 micron transition zone.

The statistical variance associated with guard hair counting increases sharply as the target coarse hair percentage drops below 0.2 percent. A lot tested with a sample size of 1,000 fibers carries a confidence interval of plus or minus 0.15 percent on a declared guard hair level of 0.3 percent. Increasing the sample size to 4,000 fibers narrows this tolerance band to plus or minus 0.05 percent, providing the precision needed to clear tight buyer specifications.

Discrepancies between origin test reports and destination testing houses frequently stem from differences in snippet length preparation, where longer snippets skew mass conversion equations toward heavy guard hair components. The exact threshold where fine hair transitions to coarse guard hair remains an open area of technical debate, specifically whether 30 microns or 28 microns serves as the definitive cutoff for commercial grade assignment.

Dispute

Sourcing contracts frequently trigger commercial claims when destination laboratory reports return residual coarse hair values higher than origin declarations, while shifts in moisture regain further alter invoice weights.

Trading contracts for dehaired cashmere specify maximum acceptable limits for residual guard hair, mean fiber diameter, and coefficient of variation of diameter. A contract specifying a maximum guard hair content of 0.5 percent by mass allows no delivery tolerance unless explicit variance bands appear in the purchase agreement. When a buyer laboratory reports 0.8 percent coarse hair on arrival, the commercial value of the lot drops, triggering re-testing protocols or price re-negotiations.

Contractual Specifications and Laboratory Variance Tolerance

Establishing commercial compliance relies on standard sampling rules defined in IWTO protocols. Core sampling bales at a minimum rate of twenty percent of the total bale count ensures representative drawing of fiber from outer and inner core zones. Moisture regain testing under ISO 6741 must accompany composition testing, adjusting the invoiced weight to the standard 13 percent commercial regain level for dehaired cashmere.

• Core Sample Representative Drawing establishes that specimen cores originate from all depth zones of at least one-fifth of the delivered lot bales.
• Inter-Laboratory Testing Protocol defines the selection of an independent accredited reference lab when buyer and seller test results differ by more than 0.2 percentage points.
• Moisture Correction Standard applies official regain factors to adjust physical weight declarations to clean dry weight plus agreed commercial moisture allowances.
• Penalty Deduction Scale enforces systematic price reductions per clean kilogram for every tenth of a percent that coarse hair exceeds the contracted maximum limit.

Because clean yield directly dictates landed cost, sampling errors represent the dominant source of inter-laboratory dispute. Bales containing unevenly distributed residual guard hair produce widely varying test results if sampling rods take fibers primarily from bale edges where coarse hair tends to accumulate during hydraulic baling compression.

Standard purchase contracts incorporate arbitration terms stating that where a second independent test confirms guard hair content exceeding contract limits by more than 0.3 percent, the buyer holds the unconditional right to reject the shipment with full return freight paid by the seller.

Ledger

Commercial valuation translates clean down yield and residual coarse hair fractions directly into landed cost per clean kilogram of spun yarn, with processing losses further compounding the unit price.

Raw grease cashmere pricing reflects a calculation based on expected scoured yield, down content, and dehairing difficulty. A buyer purchasing grease cashmere at 45 USD per kilogram with an expected clean down yield of 40 percent pays an effective base fiber price of 112.50 USD per clean kilogram before dehairing processing costs. If actual clean yield falls to 35 percent due to higher guard hair and dirt content, the raw fiber cost jumps to 128.57 USD per clean kilogram.

Financial Mechanics of Dehairing Yield and down Valuation

Consider a commercial worked example evaluating a 10,000 kilogram raw grease cashmere lot processed through two distinct dehairing regimes. Regime A targets a standard quality grade with 0.8 percent residual guard hair. Regime B targets a premium grade with 0.2 percent residual guard hair.

The arithmetic proves that achieving a lower residual coarse hair threshold increases the net fiber cost per clean kilogram by 23.93 USD, representing an 18.8 percent cost premium. This cost increase stems from both higher processing fees and the direct loss of down fibers swept into the waste stream during aggressive carding.

A raw lot yielding forty-two percent clean down at a zero point three percent residual coarse hair limit incurs a processing cost twenty-four percent higher than standard dehairing to a one point zero percent threshold.

Calculating the true landed cost per finished meter of woven or knitted fabric requires incorporating spinning waste allowances. Fine count worsted spinning of cashmere down with a mean fiber diameter of 15.2 microns incurs a spinning waste factor of 8 to 12 percent. Coarse hair presence above contracted limits causes fiber breakage on high-speed ring spinning frames, driving spinning waste toward 15 percent and increasing yarn production expenses far beyond the initial raw fiber price differential.

Failing to verify coarse hair content before committing a dehaired lot to the dyehouse results in catastrophic fabric rejections when coarse hairs resist dye uptake and surface as pale, rigid specks across finished dark woven garments.