Colour Performance / Perspiration / Evaluation
How Is Colour Fastness to Perspiration Tested in Knitwear?
Perspiration fastness is a controlled contact test. It separates change in the coloured knit from transfer onto an adjacent fabric under a specified solution, pressure, temperature, and time.
Colour fastness to perspiration is tested by combining a dyed or printed knit specimen with a specified adjacent fabric, thoroughly wetting the composite with a standardized simulated-perspiration solution, removing excess liquid as the method directs, placing the composite under prescribed pressure in a perspiration-testing device, and holding it at controlled temperature and time. After separation, drying, and conditioning, the specimen is assessed for colour change and the adjacent fabric for staining. ISO 105-E04 includes separate acid and alkaline solutions; the current AATCC TM15 procedure uses simulated acid perspiration. Results from different methods or solution systems must not be treated as equivalent.
The test fixes chemistry and contact rather than imitating an entire day of wear
ISO 105-E04 applies to textiles of all kinds and forms and determines resistance to human perspiration through controlled acid and alkaline exposures. AATCC TM15 evaluates resistance to simulated acid perspiration for dyed, printed, or otherwise coloured textile materials. The chosen standard, edition, solution, pH, specimen ratio, wetting procedure, pressure, incubation, drying, and assessment scales belong in the report. Writing only “perspiration: pass” removes the conditions needed to understand the result.
A representative piece of the coloured material is placed in contact with one or more prescribed adjacent fabrics. A multifibre adjacent fabric is often used because its standardized fibre stripes reveal transfer affinity to different fibre classes. The assembly is saturated with the specified freshly prepared solution and handled to the method-defined liquor uptake or drainage condition. Incomplete wetting can leave an unchallenged area; uncontrolled excess liquid can create migration conditions outside the method.
The wet composite is aligned between plates in a perspirometer or equivalent specified device and subjected to a defined pressure. It is then held at the required elevated temperature for the stated period. Contact pressure keeps specimen and adjacent fabric together while the solution acts. After exposure, the components are separated and dried as directed so that continued contact during drying does not add an unstandardized transfer stage.
Sampling should include the actual coloured materials and constructions that will touch the body or another layer. Necklines, underarm panels, waistbands, cuffs, plated backs, intarsia boundaries, jacquard floats, dark grounds, and high-contrast colour combinations may deserve targeted specimens. Yarn-dyed panels, garment-dyed goods, prints, embroideries, trims, and seam combinations can require separate assessment because one generic swatch cannot represent every dye class, fibre, or aftertreatment in the garment.
Two grades answer two questions
Colour change asks what happened to the original specimen. Staining asks how much colour transferred to the adjacent material. A satisfactory result in one category does not cancel a weak result in the other.
Colour change and staining are assessed separately
After conditioning, the tested specimen is compared with an untested original for change in colour, commonly with the grey scale described in ISO 105-A02 or an allowed instrumental procedure. The adjacent fabric is evaluated for staining with the scale described in ISO 105-A03. Conventional grades run from 5, little or no visible difference, toward 1, severe change or staining. Intermediate half-grades may be used where the method permits.
The two observations describe different failure modes. A knit can retain its own depth yet release enough unfixed or weakly bound colourant to stain an adjacent fibre. Another specimen can shift in hue or depth while producing limited transfer. Multifibre staining should be recorded by fibre stripe rather than collapsed into one unexplained number, because transfer to polyamide, cotton, acetate, polyester, acrylic, or wool can differ.
There is no universal luxury-knitwear acceptance grade independent of product, shade, fibre, use, care route, destination market, and brand specification. A pale underlayer worn beneath a dark body-contact knit creates a different risk from a self-coloured accessory. The test method supplies evidence; the approved requirement supplies the decision. Visual assessment conditions, assessor competence, reference scales, and any instrumental settings must be controlled.
The test does not reproduce sweat volume, evaporation rate, skin microbiology, sebum, deodorant, sunscreen, repeated abrasion, laundering, or sunlight during wear. Perspiration combined with light is a separate exposure question, as are wet rubbing and washing. A strong grade in one method does not predict all other routes of colour change or transfer.
Dye fixation, fibre chemistry, and knit construction all affect the result
Fibre and dye class establish the primary chemical system. Reactive dyes on cellulosic fibres depend on fixation and removal of hydrolysed colour; acid dyes on wool or polyamide depend on dye selection, bath control, and aftertreatment; disperse dyes on polyester require control of surface deposits and reduction clearing where applicable. Pigments depend on binder integrity. Blends combine systems, and a shade that appears uniform can contain components with different perspiration responses.
Shade depth matters because dark or saturated colours generally involve more colourant and can expose weaknesses in fixation or wash-off. It is still incorrect to assume that every dark shade will fail or every pale shade will pass. Dye recipe, water quality, pH, time, temperature, auxiliaries, rinsing, neutralization, finishing, drying, storage, and contamination can all change the available mobile colour. Each colourway should be evaluated according to its material system and risk rather than inherited from a visual neighbour.
Knit architecture controls access and contact. Open structures admit solution readily; compact double-bed structures may wet and dry differently; pile and brushed surfaces increase fibre contact; floats can place a contrasting yarn directly against the adjacent fabric; plating can expose a body-facing yarn that is not prominent on the technical face. High relief may also produce uneven contact unless the specimen preparation follows the method carefully.
Finishes can improve or complicate performance. Fixing agents, softeners, resins, lubricants, optical brighteners, and residual process chemicals may alter shade, handle, pH, or migration. Steam and pressing can move surface deposits without correcting inadequate fixation. Testing should therefore use material representative of the intended finished state, with lot, colourway, process route, and any preconditioning recorded.
A weak grade should lead to diagnosis, not cosmetic correction
During development, the first step is to identify whether the weakness is colour change, staining, or both; whether it occurs in acid, alkaline, or the specified acid-only route; and which adjacent fibre shows transfer. The laboratory record should retain individual grades, solution identity, specimen orientation, lot, shade, fibre composition, dye or print route where known, finishing state, and any deviation. That evidence narrows the production investigation.
Corrective work may involve reviewing dye selection, fixation, wash-off, reduction clearing, neutralization, bath pH, water quality, aftertreatment, finish compatibility, or contamination. If transfer is localized to a body-facing plated yarn or one jacquard component, the solution may belong to yarn allocation or construction rather than the whole ground shade. Repeated application of a fixing agent without checking handle, shade, light fastness, and downstream processing can exchange one problem for another.
Retesting must use the same method and a specimen that represents the corrected bulk route. A passing laboratory correction made on a hand-treated fragment does not establish production control. Approval should connect the measured outcome to the final yarn lot, dyehouse recipe, knitting arrangement, finishing sequence, care claim, and risk of contact with pale materials. Examples of structure and material placement appear in Work; Anne's development remit is described in About. Project-specific questions can be sent through the contact form.
Common questions about perspiration fastness
Why are acid and alkaline perspiration tests different?
They use different controlled solution chemistries and can interact differently with fibres, dyes, and finishes. ISO 105-E04 includes acid and alkaline exposures, while current AATCC TM15 uses simulated acid perspiration; the method must be identified.
Does perspiration fastness test fading or staining?
It assesses both, separately. Colour change is graded on the original specimen, while staining is graded on the adjacent fabric, often by each fibre stripe in a multifibre fabric.
Is grade 5 always required?
No universal grade applies to every product. Acceptance depends on the written specification, end use, shade, fibre system, contact risk, market, and test method. The grade is evidence, not a self-contained commercial decision.
Can the test predict deodorant or sunscreen marks?
Not by itself. Standard simulated perspiration does not reproduce every cosmetic ingredient, skin oil, microbiological condition, friction sequence, or sunlight exposure. Additional product-specific testing may be necessary.
Why can a dark knit stain a pale layer even when it looks unchanged?
A small amount of mobile colour can transfer without producing an obvious visual loss of depth in the dark specimen. That is why specimen colour change and adjacent-fabric staining are graded independently.
Does every colourway need testing?
Risk-based programmes may group technically equivalent routes, but a visual shade family does not prove equivalent dye chemistry or fixation. New dyes, fibre blends, depths, suppliers, finishes, and process changes require evidence appropriate to the specification.
Perspiration fastness is one defined exposure in a larger colour system
The result becomes actionable when solution chemistry, pressure, time, temperature, specimen state, colour-change grade, staining by adjacent fibre, and production identity remain visible. Used that way, the test supports a precise conversation between colour development, knit construction, finishing, quality control, and intended wear without claiming to simulate every condition against the body.
Perspiration and light are separate colour exposures. The companion note on how colour fastness to light is tested describes xenon-arc conditions, blue wool references, shade sampling, and why a laboratory grade cannot be converted directly into years of use.