First explain where the garment will be displayed, what light it will receive and the colour change the buyer wants to avoid. Then determine sample coverage using the actual composition, colour, yarn and finish. If a lightfastness report is needed, agree the method, edition, specimen preparation, exposure conditions, rating method and acceptance requirements with the laboratory in advance. Also establish repeatable store observations and records. A laboratory result helps assess the tested sample under the selected conditions; it cannot be converted directly into a display life for any store or guarantee that other colours or batches will not fade.
This guide is for buying and quality teams displaying knitwear in shop windows, showrooms or on retail rails. Lightfastness concerns colour change after light exposure; wash staining, rubbing transfer and perspiration-related change require separate risk and method decisions. The dark knitwear rubbing-transfer guide discusses staining of pale underlayers through contact, while the perspiration colour-change and staining guide addresses perspiration conditions. Here the focus is colour change after light exposure and display decisions.
Describe the use environment and colour risk first
Give the supplier and test provider the style, colour, yarn and dye lot, fibre composition, knit structure and finishing revision. Say whether the product will be in a window, on a shelf near a window or on an indoor rail. Record possible direct sunlight, lamp type, exposed areas, expected daily display time and rotation. Mark unknown conditions as pending. Stores can differ with season, window orientation, shade and lighting, so one store's observations cannot represent every store.
The Canadian Conservation Institute's textile preservation guidance explains that visible light and ultraviolet radiation can deteriorate textiles, with effects depending on intensity, exposure time and the proportion of UV; light damage is cumulative and irreversible. The guidance concerns collections, not a retail garment acceptance standard or fading forecast. It supports controlling and recording exposure, not promising how long a garment can be displayed. Even with UV filtration, do not assume colour change is completely eliminated.
| Decision | What to record or agree | What cannot be inferred |
|---|---|---|
| Product and coverage | Style, colour, yarn lot, construction, finish and sample areas | A pass for one colour represents every colour and batch |
| Laboratory method | Method and edition, preparation, exposure and rating method, report contents | Grades from any two methods or conditions are directly interchangeable |
| Acceptance and responsibility | Buyer requirement, test provider, cost, decision-maker and open items | A test method sets a pass requirement for every order |
| Store observation | Lighting or sunlight, position, time, reference sample and observation method | A store observation is a standard laboratory test |
| Changes and review | New colour, yarn, dye lot, finish or display conditions | The original report automatically covers substitutions or new settings |
This is a project communication checklist, not a test standard. Agree who supplies samples, who decides the result and what happens if requirements are missed before scheduling tests and order milestones.
Distinguish laboratory methods from real display
The Irish adoption preview of ISO 105-B02:2014 describes a method using an artificial source representative of natural daylight to determine colour change in textiles and notes that results from two sets of blue-wool references may not be identical. The method name and edition are only a start: confirm the applicable procedure, reference, preparation, exposure endpoint and report contents with the laboratory. Do not simply write “lightfastness pass”, or treat ratings under different methods or conditions as equivalent.
The public AATCC TM16.3 summary lists different xenon-arc options and states that the relationship between a test and actual use exposure must be determined and agreed by the contracting parties. Ask the laboratory how it will report conditions, ratings and any deviations. If the purchase agreement requires another method or a newer edition, confirm its applicability first; do not assume ISO and AATCC results are interchangeable. This guide specifies no grade, tolerance or test fee and does not claim WTBF has a report for this product.
A prescribed laboratory exposure is not the sunlight, lamps and display duration in a particular shop. Imagine two stores display the same style and colour, one near a sunlit window and one under indoor lamps. Even if the submitted sample receives one report, that does not establish that both stores will see the same rate of change or saleable period. This hypothetical example illustrates different settings; it is not a WTBF customer case or a life prediction. Where commercial acceptance is needed, have buyer and supplier agree the applicable requirement and review process for a missed requirement beforehand.
Ensure submitted samples correspond to the order
Select material or garments representative of the intended production state. Record style and colour, yarn and dye lot, construction, finish, sample date and revision. Based on order risk and laboratory advice, decide which colours, components and batches to test. For multicolour jacquard or decorations of different materials, identify the areas to assess; do not assume testing one colour area covers all. The laboratory and parties should agree the number and location of specimens and whether retained samples are needed. The report's sample identity must link to the approved order version.
Tell the laboratory and record if the sample was washed, steamed or specially finished before submission; do not compare different preparation states as if they were the same. When testing adds time and cost, agree who pays, when the report is due and who approves it; sampling, production and shipment plans should reflect those milestones. A sample meeting an agreed requirement does not automatically prove the whole batch or future replacement yarn, dye or finish is the same. If material or lot changes, confirm with buyer and laboratory whether retesting is needed and its scope.
Use a reference for store observation without calling it a standard test
For internal display observation, choose an identifiable sample garment or swatch not intended for sale and retain an unexposed reference of the same style, colour, lot and preparation. Agree position, orientation, start and end times, and photographic conditions in advance. Record window position, lighting, shading, actual rotation and any wetting, cleaning or finishing. Compare exposed and reference samples under the same agreed light and background, recording location, direction and extent of change. Identify the sample and observation date in photos. Do not expose customer sale stock to unapproved conditions for a trial.
Inside and outside surfaces or folds may already differ because of finishing, knitting or colour, so a photograph alone cannot establish cause. If a difference appears, retain the reference, display records and affected sample; review test coverage, lot and display conditions with the quality team. Further laboratory or supplier assessment may be requested. Internal display trials lack controlled laboratory conditions: do not call them a pass to a standard lightfastness test or infer results for other stores. Agree beforehand who decides whether to remove an obviously changed item from display, isolate it or review it, rather than treating an unresolved issue as released.
Link the report to sales handling
The approval record should include product and colour; tested sample version and batch; method and conditions; report date; buyer requirement; result; decision-maker; order scope covered and open items. Where needed, keep the colour reference, store observation and report under the same version record. Do not confuse colour matching under different illuminants with lightfastness: the knit-set colour matching under different lights guide addresses the relationship between colours, not light ageing.
Depending on actual store conditions, agree rotation, avoidance of direct sunlight, checks and record ownership; do not prescribe a fixed safe duration for every fabric. If colour change appears, the parties should decide whether to continue display, convert the piece to a non-sale sample or take another action, following brand policy and applicable local rules. After changing dyeing, material or finish, update the link between sample and report before deciding on retesting; put risk and coverage in the change record.
Use the WTBF inquiry page to provide the style reference, composition and colour direction, quantity per style and colour, planned display setting, destination and target arrival date. Attach the proposed method, grade or customer requirement and existing test records. Ask about available samples, testing arrangements, charges, report timing and review after changes. Browse knit pullovers for style references. Reports, timing and results depend on the confirmed project.