The selection of the correct adjacent fabric is one of the most decisive steps in colour fastness to perspiration testing, because the staining grade of a textile is read directly on the undyed lining fabric pressed against it. This technical article explains how monofibre and multifibre adjacent fabrics are specified under ISO 105-E04, GB/T 3922 and related standards, and how accredited third-party laboratories design and evaluate adjacent fabric selection trials. A clear understanding of these selection rules is essential for manufacturers, buyers and laboratories that need comparable and defensible staining results.
Technical Overview
Colour fastness to perspiration measures the resistance of the colour of a dyed or printed textile to the action of artificial human sweat. In the test, a specimen is soaked in an acidic or alkaline perspiration solution and held under mechanical pressure in intimate contact with one or more undyed, standardized fabrics — the adjacent fabrics, also known as lining or backing fabrics. Any dye that migrates out of the specimen during the exposure is absorbed by the adjacent fabric, and the severity of this transfer is graded as the staining fastness.
A dye molecule only migrates appreciably to a receptor fibre for which it has chemical affinity. A reactive dye released from cotton, for example, will stain a wool or polyamide stripe far more strongly than a polyester stripe. The reported staining grade is therefore not an absolute property of the specimen alone, but of the specimen–adjacent fabric pair, and an inappropriate selection can shift the reported grade by one or more steps. Incorrect adjacent fabric selection is a classic cause of disputed results between a supplier and a buyer, or between two accredited third-party laboratories.
The adjacent fabric selection test consequently has two related objectives. The first is to verify that the adjacent fabric itself conforms to the specification of the relevant part of the ISO 105-F series (or the corresponding GB/T 7568 series and GB/T 11404 in the Chinese national framework), including its staining response to prescribed control dyes. The second is to establish, for a given article, which configuration — the monofibre pair or the multifibre strip — is required or most appropriate under the governing fastness method, such as ISO 105-E04, GB/T 3922 or JIS L 0848.
Testing Samples
Monofibre Adjacent Fabrics (ISO 105-F01 to F07)
Monofibre adjacent fabrics are undyed, plain-woven standard fabrics made from a single fibre type. Each part of the ISO 105-F series, mirrored by the GB/T 7568 series, defines the construction, mass per unit area, whiteness, absorbency and staining behaviour of one fabric:
- ISO 105-F01 — wool adjacent fabric, typically the second fabric paired with cellulosic specimens
- ISO 105-F02 — cotton and viscose adjacent fabric
- ISO 105-F03 — polyamide (nylon) adjacent fabric
- ISO 105-F04 — polyester adjacent fabric
- ISO 105-F05 — acrylic adjacent fabric
- ISO 105-F06 — silk adjacent fabric
- ISO 105-F07 — secondary cellulose acetate adjacent fabric
Multifibre Adjacent Fabrics (ISO 105-F10)
A multifibre adjacent fabric is a single woven strip composed of six fibre stripes of equal width, allowing one piece to serve as a universal receptor for dyes of widely different chemistry. Two principal types exist:
- Type 1 (historically designated DW): wool, acrylic, polyester, polyamide, cotton and cellulose acetate stripes; it is the default configuration in most European and GB test methods
- Type 2 (historically designated TV): viscose, cotton, polyamide, polyester, acrylic and cellulose triacetate stripes; it excludes wool and acetate and is preferred when a wool stripe would overstate staining or when the governing method excludes wool
Because the DW strip contains wool, a specimen dyed with wool-affine dyes may produce a lower grade on the wool stripe than on the paired monofibre configuration, and this difference must be recognized when comparing reports.
Test Specimens and Composition Categories
Under ISO 105-E04 and GB/T 3922, the specimen measures 100 mm × 40 mm; North American practice uses a smaller square specimen. Specimens are grouped by fibre composition before testing, since the composition category determines the adjacent fabric selection: single-fibre articles, two-component blends, and articles of unknown or complex composition each follow different rules described below.
Testing Items
The selection test and the perspiration fastness determination it supports involve the following reported items:
- Staining of the adjacent fabric in the acidic perspiration solution, graded 1 to 5 with the grey scale for staining (ISO 105-A03)
- Staining of the adjacent fabric in the alkaline perspiration solution, graded in the same manner
- Colour change of the specimen itself, graded 1 to 5 with the grey scale for assessing change in colour (ISO 105-A02)
- For multifibre strips, the staining grade of each individual fibre stripe, reported separately
- Conformity verification of the adjacent fabric lot: mass per unit area, whiteness, wetting and absorbency, dimensional stability during the wet treatment, and staining response against prescribed control dyes within specified grade windows
- Comparative data from parallel trials using monofibre and multifibre configurations, used to justify the selected test arrangement
Testing Methods
Preparation of Artificial Perspiration Solutions
The acidic solution per ISO 105-E04 and GB/T 3922 contains L-histidine monohydrochloride monohydrate, sodium chloride and disodium hydrogen phosphate, adjusted to pH 5.5 ± 0.2; the alkaline solution contains the same histidine and salt base with a higher phosphate level, adjusted to pH 8.0 ± 0.2. Both solutions must be freshly prepared, and their pH verified before use, because solution pH strongly influences dye migration and therefore the staining grades on which the selection decision is based.
Selection Rules by Fibre Composition
The adjacent fabric arrangement follows the composition of the article under test:
- Single-fibre article: place the specimen between two monofibre adjacent fabrics — the first of the same fibre as the specimen, the second as specified by the method: wool or silk specimens are paired with cotton; cotton, linen and viscose specimens are paired with wool; polyamide, polyester and acrylic specimens are paired with wool or cotton as the standard or the client directs
- Two-component blend: use two monofibre adjacent fabrics corresponding to the two principal fibres, or a single multifibre strip
- Unknown or complex composition: use a single multifibre adjacent fabric, which ensures every major dye-fibre interaction is captured
- Contractual override: purchase contracts and certain eco-labelling schemes may mandate the multifibre DW configuration regardless of composition, and this instruction takes precedence
Exposure Procedure
The composite assembly of specimen and adjacent fabric is immersed in the test solution for approximately 30 minutes at a liquor ratio of about 50:1, so that it is completely wetted out without mechanical agitation. Excess solution is removed, the assembly is placed between plates of a perspirometer under a standardized pressure equivalent to 12.5 kPa, and the loaded device is incubated at 37 ± 2 °C for 4 hours in accordance with ISO 105-E04 and GB/T 3922. The assembly is then dried in air at a temperature not exceeding 60 °C, keeping the specimen and adjacent fabric in contact until dry. North American practice follows a different parameter set, with a single acidic solution near pH 4.3 and incubation at 38 ± 1 °C.
Assessment and Reporting
After conditioning, the staining on each adjacent fabric or stripe is assessed in a standardized lighting environment against the grey scale for staining, and the change in colour of the specimen is assessed against the grey scale for colour change. When a multifibre strip is used, the grade of every stripe is reported individually, and the lowest grade normally governs conformity. Reports must state the adjacent fabric configuration used, since monofibre and multifibre results are not interchangeable.
Designing the Selection Trial
Where the applicable configuration is ambiguous or disputed, a selection trial is performed: identical specimens are tested in parallel with the monofibre pair and with the multifibre strip, in both acidic and alkaline media, ideally in duplicate. The resulting grade profiles are compared, the configuration demanded by the governing method or contract is identified, and the trial record is retained as objective evidence during method validation or dispute resolution.
Applications
Adjacent fabric selection testing supports a wide range of industrial and regulatory activities:
- Internal quality control of dyed and printed fabrics and garments before dispatch, and incoming inspection at garment and accessory factories
- Demonstration of compliance with national product safety and quality standards that set minimum perspiration fastness grades
- Verification against buyer technical manuals and purchase contracts, which frequently specify the exact adjacent fabric configuration
- Support of eco-labelling and restricted-substance programmes that include wet fastness requirements
- Research and development of dye–fibre systems, auxiliaries and finishing recipes, where staining profiles across six fibres guide formulation work
- Inter-laboratory comparability studies and third-party arbitration, where a documented selection trial resolves configuration-related discrepancies
- Batch release testing by adjacent fabric manufacturers, confirming each production lot stains within the control-dye windows of the ISO 105-F specifications
FAQ
Q: When must a multifibre adjacent fabric be used instead of a monofibre pair?
A: A multifibre strip is mandatory or strongly preferred when the fibre composition is unknown, when the article is a complex blend, or when the purchase contract or governing specification names it explicitly. For simple single-fibre articles, the two-piece monofibre arrangement specified by the method applies.
Q: What is the practical difference between the DW and TV multifibre strips?
A: The DW strip contains wool and cellulose acetate, which are highly receptive to acid and disperse dyes respectively, so it tends to reveal the worst-case staining. The TV strip replaces these with viscose and cellulose triacetate and avoids the sometimes exaggerated wool response, which is why certain methods and buyers specify TV.
Q: Why is wool paired with cellulosic specimens?
A: Wool carries positive ionic sites under perspiration-test conditions and shows strong affinity for anionic dyes that bleed from cotton, viscose and linen. It therefore acts as a sensitive receptor that reveals cross-staining potential, for example onto wool or nylon components of a garment in actual wear.
Q: Can monofibre and multifibre configurations give different grades for the same fabric?
A: Yes. Differences of half to one grey scale step are common, mainly on the wool and acetate stripes. This is precisely why the test report must identify the configuration used and why selection trials are performed when comparing results from different sources.
Q: How often should adjacent fabric lots be verified?
A: Each new lot should be checked for the conformity items of the ISO 105-F or GB/T 7568 specifications, including the staining response to the prescribed control dyes, before it is placed into routine perspiration testing. Storage conditions and shelf life should also be controlled, as ageing can alter whiteness and absorbency.