Colour Performance / Washing / Evaluation
How Is Colour Fastness to Washing Tested in Knitwear?
Wash fastness separates two observations: change in the specimen's colour and staining of an adjacent fabric. Method, detergent, temperature, mechanical action, time, and assessment scale define what the grades mean.
Colour fastness to washing is tested by attaching the coloured knit to a specified adjacent fabric, treating the composite specimen in a controlled detergent solution under a prescribed combination of liquor volume, temperature, time, and mechanical action, then rinsing, drying, conditioning, and assessing two outcomes separately: colour change in the original specimen and staining of the adjacent fabric. The report must name the exact method and option. A grade without the wash procedure, specimen face, shade, and assessment basis does not establish a reproducible performance claim.
The test sequence creates a controlled laundering challenge
ISO 105-C06 covers colour fastness to domestic and commercial laundering through a range of specified procedures. AATCC TM61 provides accelerated laundering evaluations in the AATCC system; under stated conditions, a 45-minute procedure can approximate the colour loss and surface change of multiple home or commercial launderings. The methods are not automatic equivalents. Different detergents, bath ratios, temperatures, apparatus, containers, mechanical elements, and procedure severities mean that a pass under one option cannot be translated casually into another.
The test begins with a representative specimen. For a plain colour, the sampled area should reflect the production fabric or garment state. For a stripe, intarsia, jacquard, print, plated structure, embroidery, trim, or colour-block junction, sampling should expose the colour systems and interfaces that matter. The chosen technical face and back need to be recorded because a plated knit may put one yarn predominantly against the adjacent fabric while another forms the visible surface.
The coloured specimen is combined with an adjacent textile. Depending on the method, this may be a prescribed single-fibre material or a multifibre adjacent fabric containing several fibre components. It acts as a controlled receiver for colour released during treatment. Staining on each component can reveal affinity between the released colourant and a particular fibre. A random white studio cloth cannot substitute for the standardized receiver because fibre content, construction, pretreatment, whiteness, and absorbency all affect deposition.
The composite is placed in the specified vessel with reference detergent and the defined liquor. Temperature, duration, agitation, steel balls or other mechanical elements where required, and any bleach condition belong to the selected procedure. After treatment, the specimen is rinsed and dried exactly as directed, with the coloured and adjacent components positioned to avoid unintended transfer. Laboratory controls should include water quality, detergent identity and age, machine loading, temperature verification, and clean apparatus.
AATCC notes that standardized detergent, ballast, and machine conditions improve comparability in laundering work. Optical brighteners also matter: they can alter the apparent whiteness and colour reading of a receiver or specimen. The selected standard detergent and any departure from it should remain visible in the report. A household product chosen for convenience introduces surfactants, enzymes, brighteners, fragrance, builders, and concentration variables that the result cannot disentangle.
Two grades answer two questions
Colour change records what happened to the tested shade. Staining records what transferred to the adjacent fabric. One can be acceptable while the other is not, so they should never be merged into a single wash-fastness number.
Colour change and staining are assessed independently
After drying and conditioning, the treated specimen is compared with an untreated original under controlled viewing conditions or an approved instrumental procedure. ISO 105-A02 defines the grey scale for assessing change in colour; ISO 105-A03 defines the grey scale for staining. In the common five-step framework, grade 5 represents little or no perceptible change or staining and grade 1 represents severe change or staining, with intermediate and half grades where the method permits. The grade is meaningful only with its observation type and method.
Colour change can include loss of depth, shift in hue, change in chroma, or an altered surface that changes light reflection. Knit distortion, pilling, felting, fibrillation, or flattening can make a shade appear different even when dye loss is not the only mechanism. The assessor should note abnormal surface change rather than forcing every visual difference into a dye diagnosis. Separate dimensional and appearance tests are needed when those properties are product requirements.
Staining is read on the adjacent fabric, often by fibre component. It indicates colour transferred into or onto the receiver during the test. Loose fibres, pigment particles, unfixed dye, hydrolysed reactive dye, inadequate reduction clearing, poor wash-off, finish migration, or contamination can produce superficially similar marks through different mechanisms. The result locates a risk; process records and controlled comparisons identify the cause.
Acceptance limits belong to the product specification, shade, fibre system, care claim, and contact risk. There is no universal grade that defines luxury knitwear. A deep lining next to a pale blouse, a contrast placket, an unlined intarsia dress, a monochrome outer layer, and a washable infant product do not present the same consequence if colour transfers. The method and threshold should be agreed before testing, not selected after seeing the result.
Fibre-dye chemistry and knit architecture both affect wash fastness
Wash fastness begins with the compatibility and control of fibre, colourant, and process. Dye class, molecular size, fibre affinity, penetration, fixation, pH, electrolyte, temperature profile, dwell time, rinsing, soaping, reduction clearing, curing, and final finish can all affect what remains mobile. A dark shade is not automatically poor, but a higher colourant concentration can make incomplete fixation or wash-off more visible. Each production recipe and colourway requires evidence.
Blends and mélange effects add complexity. Wool, cotton, viscose, polyamide, polyester, acrylic, acetate, and elastane do not share one dye route or one receiver affinity. A cross-dyed yarn may contain several fibre components with different fixation histories. In a mélange, a small strongly coloured component can stain even when the average surface looks stable. Testing should preserve the actual blend distribution rather than substituting a nominally similar solid fabric.
Knit construction governs exposure and movement. Tuck stitches, floats, pile, brushed yarns, bouclé, chenille, loose marls, and open transfers can release fibres or present more coloured surface to the receiver. Plating can place a dark yarn on one face and a pale or functional yarn on the other; intarsia and jacquard create different colour boundaries, floats, and layers. Seams and trims can trap detergent or bring dissimilar materials into sustained contact during drying.
Wash fastness is also distinct from colour fastness to rubbing. Washing evaluates release and transfer in a detergent bath under a defined thermal and mechanical challenge. Rubbing evaluates transfer by controlled friction to a standard cloth under dry or wet conditions. A quality can perform well in one and poorly in the other because the mobilizing mechanisms differ.
Development testing should trace shade, state, and recipe
During technical development, the report should identify the standard and edition, exact procedure code, detergent, bleach condition if any, bath ratio or specified liquor, apparatus, temperature, time, mechanical elements, specimen dimensions, technical face, adjacent fabric, preconditioning, pretreatment, drying, colour-change grade, staining grade by fibre component, assessment method, colourway, yarn and dye lot, and production state. Individual results should remain available when replicates are used.
Testing should occur on the state that will be sold, not only on an early lab dip or unwashed knitdown. Factory washing, softening, brushing, milling, steam, pressing, and resin or enzyme treatment can improve or damage the result. Representative production material confirms that dyeing and aftertreatment remain controlled at scale. Retained untreated and tested specimens allow later comparison when a shade, finish, or supplier changes.
If a result is below target, correction follows the mechanism. Dye-house controls may require fixation, pH, temperature, wash-off, reduction clearing, or bath contamination review. Pigment systems may require binder and curing review. Fibre shedding or surface abrasion may point to yarn and finish rather than dye fixation alone. Repeating the same test without documenting the process change creates another grade but no usable production knowledge.
Selected material and colour applications appear in Work. The relationship between creative direction, technical development, and factory translation is outlined in About. For a project-specific colour or care brief, use the contact form.
Common questions about wash colour fastness
What does grade 5 wash fastness mean?
On the common grey-scale framework, grade 5 indicates little or no perceptible change or staining. It must still be labelled as colour change or staining and tied to the exact test procedure; it is not a universal statement about every wash condition.
What is the difference between fading and bleeding?
Fading describes change in the tested specimen's colour. Bleeding commonly describes colour released and deposited elsewhere, represented in the test by staining of the adjacent fabric. Both can occur in one test and receive separate grades.
Is wash fastness the same as rubbing fastness?
No. Washing uses detergent, liquor, temperature, time, and mechanical action. Rubbing uses controlled friction against a standard cloth. The tests expose different transfer mechanisms and neither result predicts the other.
Why do dark colours need separate testing?
Each shade has its own recipe, concentration, fixation, and wash-off history. Dark shades can make small transfer more visible, but depth alone does not determine performance. Every materially different colourway needs representative evidence.
Can a home wash replace a standard wash-fastness test?
No. A home wash can reveal a practical concern but does not control detergent, ballast, water, machine action, temperature, liquor, receiver fabric, or assessment. It cannot support a comparable technical grade.
Why is multifibre adjacent fabric used?
Its standardized fibre components show how released colour stains different materials under the same treatment. This is especially useful when the end product may contact linings, shirts, underwear, trims, or other garments of varied composition.
Wash fastness is a traceable fibre-colour-process result
The useful conclusion is not simply that a shade "holds." It is that a named knit, colourway, face, production state, adjacent fabric, and controlled procedure produced stated colour-change and staining grades. That evidence can then guide colour placement, dye-house correction, material approval, care instructions, and production release without treating all colour durability as one property.
Washing is one route of colour movement. Compare how colour fastness to perspiration is tested to see how simulated solution, controlled contact, pressure, and incubation create a separate colour-change and staining result.