01 COLOUR & YELLOWNESS ACCEPTANCE EVIDENCE
Plastic-film yellowness index vs colour difference: keep YI and Delta E separate
Yellowness index is a one-number description with a limited specimen scope; colour difference compares two controlled colour stimuli under a declared coordinate system and formula. Do not convert one into the other. First identify the film, appearance class, reference, reflectance or transmittance route, geometry, backing, illuminant, observer and formula, then apply only the buyer-approved tolerance to comparable records.
02 DECISION FRAME
Yellowness index is not a substitute for colour difference
ASTM E313-20(2025) addresses yellowness or whiteness indices for white, near-white or colourless object-colour specimens and limits comparison to the same material and general appearance. ASTM D2244-25 calculates colour tolerances and small colour differences for opaque specimens and requires purchaser and seller to agree the tolerance and calculation procedure. ISO/CIE 11664-4:2019 defines CIELAB coordinates for reflecting or transmitting objects, while ISO/CIE 11664-6:2022 defines the CIEDE2000 calculation from applicable CIELAB inputs. These outputs answer related but different questions; their names do not establish specimen applicability, equivalence, conversion or acceptance.
- A buyer comparing YI, L*a*b* or colour-difference records that use different references, instruments or specimen presentations
- A converter defining colour acceptance for a plain, printed, coated, laminated, aged or otherwise identified film stage
- A receiving plan that must keep individual roll and web-location results attached to the method and buyer-owned decision rule
- Yellowness index and Delta E are not interchangeable, directly convertible or governed by one universal threshold
- ASTM D2244's opaque-specimen scope does not automatically cover a transparent or translucent film presentation
- An ASTM E313 result does not automatically apply to every coloured, metallized, fluorescent, textured or dissimilarly appearing specimen
- A typical value, sample report or one location does not approve every roll, lot, converted package or LayerSource capability
03 COMPARISON MAP
Keep specimen presentation, colour calculation and acceptance in separate evidence rows
Use this matrix to define comparable records. It supplies no preferred instrument, geometry, formula, YI or colour-difference value, tolerance or pass/fail threshold.
Swipe or scroll horizontally to review every evidence column.
| Evidence row | Question it can address | Context to retain | Conclusion it cannot create alone |
|---|---|---|---|
| Buyer decision and exact specimen | Which identified film state and commercial decision is the colour record intended to support? | Supplier document, material or candidate, construction, lot, roll, thickness, side, web location, plain/printed/coated/laminated stage and specimen history | An available grade, colour-control service, laboratory, lot release or finished-package approval |
| Appearance class and presentation | Is the specimen opaque, translucent, transparent, white, near-white, colourless, coloured, metallized or otherwise outside a cited method's public scope? | Appearance class, surface and texture, gloss, opacity or translucency, backing or background, number of layers, orientation and applicability owner | That one reflectance or transmittance setup applies to a different appearance class or presentation |
| Spectral or colourimetric acquisition | How were the source data obtained for the identified specimen and presentation? | ASTM E1164, ASTM E308 or other selected basis and edition, reflectance/transmittance mode, geometry, aperture, SCI/SCE or other reported configuration, illuminant, observer, instrument, calibration and raw record | A colour difference, yellowness value or commercial acceptance decision before the calculation and reference are defined |
| CIELAB coordinates | Which L*, a* and b* coordinates describe each controlled colour stimulus on the declared basis? | ISO/CIE 11664-4 or other selected coordinate basis, source tristimulus data, reference and test coordinates, units, calculation record and software version | CIEDE2000, yellowness, whiteness, gloss, haze or complete visual appearance from the coordinates alone |
| Colour difference | How far and in which coordinate directions does the test stimulus differ from the controlled reference? | ASTM D2244, ISO/CIE 11664-6 or another selected calculation basis, exact reference, Delta L*, Delta a*, Delta b*, declared Delta E formula, result and rounding | Equivalence among Delta E formulas, a universal tolerance, or ASTM D2244 applicability to a non-opaque specimen |
| Yellowness index | Does the method-applicable white, near-white or colourless specimen show a change toward yellow on the declared E313 basis? | ASTM E313 edition, material and general-appearance match, thickness and translucency, illuminant/observer basis, YI result, control and limitations | Complete colour difference, hue direction for every colour, Delta E conversion or applicability to a dissimilar specimen |
| Sampling and measurement variability | Do the readings represent the agreed roll, web locations and repeatability basis? | Lot and roll population, across-web and along-web map, replicate readings, individual values, average, range or other approved summary, instrument checks and excluded readings | Roll uniformity, lot acceptance or measurement-system adequacy from one unlocated value |
| Acceptance, visual review and change control | Who decides whether the identified record is acceptable and what changes reopen review? | Buyer-controlled requirement, visual-assessment conditions when required, tolerance by declared metric, rounding/uncertainty treatment, deviations, retest, disposition, approvers and supplier/process/reference changes | A universal pass level, automatic regulatory release, appearance warranty, weathering life or grade-wide approval |
04 SELECTION SEQUENCE
Move from a broad comparison to an approvable decision.
Classify the specimen before choosing the metric
Identify the exact film stage and whether the measurement concerns an opaque, translucent, transparent, white, near-white, colourless, coloured, metallized or otherwise special appearance. Send any method-scope uncertainty to the responsible laboratory.
Control the reference and measurement configuration
Freeze the reference specimen, backing or transmission presentation, side, thickness, geometry, aperture, illuminant, observer, instrument and calculation basis before comparing results.
Apply one metric-specific buyer decision
Keep YI, CIELAB coordinates, each Delta E formula and any visual assessment in separate rows. Apply only the approved tolerance to the exact metric, specimen population and evidence role.
05 RFQ INPUTS
Plastic-film yellowness and colour-difference acceptance RFQ checklist
Use exactly these twenty fields. Unknowns remain open for the buyer, supplier and responsible laboratory; this page supplies no default method configuration, conversion, value, tolerance or threshold.
Open the RFQ brief builder ↗- 01
Buyer decision, intended application, visual concern and responsible acceptance owner
- 02
Exact material or candidate, supplier-document identity, complete construction and controlled revision
- 03
Lot, roll, sample, web location, specimen ID and chain-of-custody record
- 04
Plain, printed, coated, laminated, converted, aged or other controlled specimen stage
- 05
Thickness, measured side, MD/TD or unwind orientation, surface and texture
- 06
Opaque, translucent, transparent, white, near-white, colourless, coloured, metallized or other appearance classification
- 07
Controlled reference specimen or standard, revision, storage, age and replacement history
- 08
Reflectance, transmittance or other measurement presentation selected by the responsible method owner
- 09
Geometry, aperture, specimen position, backing or background and number of stacked layers
- 10
SCI/SCE, UV component or other instrument configuration retained exactly as reported when applicable
- 11
Illuminant, observer, wavelength or integration basis and environmental conditions
- 12
Instrument, software, calibration or verification, reference materials and raw-record location
- 13
Selected ASTM E1164, ASTM E308 or other acquisition/computation method and current edition
- 14
L*, a*, b* or other declared coordinate system, individual source values and calculation record
- 15
Declared Delta E formula, exact reference comparison, Delta L*, Delta a*, Delta b* and reported colour-difference result
- 16
ASTM E313 or other declared yellowness-index method, applicability review and separate YI result
- 17
Roll and web sampling plan, replicate readings, individual results, variability and approved summary rule
- 18
Visual assessment method, viewing conditions, reviewers and relationship to instrumental disposition when required
- 19
Buyer-owned metric-specific tolerance, rounding or uncertainty treatment, deviations, retest and final disposition
- 20
Reference, material, supplier, formulation, thickness, process, instrument or method changes that trigger requalification
06 EVIDENCE BOUNDARY
Official colour standards define calculation and scope—not a LayerSource result or universal film tolerance
ASTM D2244-25 is active and publicly scopes its colour-tolerance and small-colour-difference calculations to opaque specimens; purchaser and seller must agree the permissible tolerance and calculation procedure, and results from different colour-scale systems are not assumed identical or simply convertible. ASTM E313-20(2025) is active for yellowness or whiteness indices of white, near-white or colourless object-colour specimens and limits comparison to the same material and general appearance; gloss, texture, thickness and translucency remain part of applicability. ASTM E1164-23 and ASTM E308-22 keep spectrometric acquisition, reflectance/transmittance data and CIE computation parameters visible, but do not create this film's specimen preparation or tolerance. ISO/CIE 11664-4:2019 is published and confirmed for CIELAB coordinates of reflecting or transmitting objects, and ISO/CIE 11664-6:2022 is published for CIEDE2000 calculation from applicable CIELAB inputs. ASTM E1345-24 supports retaining multiple measurements when measured colour values are compared with an established tolerance. These sources do not make YI, CIELAB components, Delta E*ab, CIEDE2000 or another colour-difference formula equivalent, interchangeable or directly convertible. This page reproduces no paid procedure, equation, weighting factor, spectral table, specimen-preparation instruction, instrument setting, geometry, aperture, backing, illuminant, observer, calibration procedure, measurement count, value, tolerance, threshold or pass/fail rule. It establishes no LayerSource coloured, colour-controlled, low-yellowing, optical, film, sheet, grade, inventory, supply, manufacturing, converting, instrument, laboratory, testing, inspection, certification, accreditation, colour-matching, weathering, shelf-life, appearance, performance capability or result. The buyer, supplier, converter and responsible laboratory must approve the current applicable method, exact specimen presentation, reference, measurement plan, metric-specific criterion and bounded disposition.
07 BUYER QUESTIONS
Resolve the assumptions that make quotes diverge.
01Is yellowness index the same as Delta E?+
No. YI is a method-bound one-number index for an applicable specimen class. Delta E is a declared colour-difference calculation between two controlled colour stimuli. Keep the original method, reference, coordinates, formula and result separate; this guide supplies no conversion.
02Can ASTM D2244 be applied automatically to clear film?+
No. ASTM D2244's public scope identifies opaque specimens. A responsible laboratory must select and approve the acquisition, specimen presentation and calculation basis for the actual transparent or translucent film rather than silently extending that scope.
03Can ASTM E313 be used for every coloured film?+
No. Its public scope concerns white, near-white or colourless object-colour specimens and its significance text limits comparisons to the same material and general appearance. Applicability must be confirmed for the exact specimen.
04Can a supplier convert YI into CIEDE2000?+
No general conversion is supported. CIEDE2000 requires applicable CIELAB input coordinates for two controlled stimuli, while YI is calculated for its own declared purpose and scope. Preserve both original records when both are required.
05Does one colour reading approve a roll or lot?+
No. Define the roll population, web map, sides, specimen preparation, repeat readings, variability treatment, buyer criterion and disposition. One unlocated result cannot establish uniformity or lot release.
06Does a colour result after weathering prove service life?+
No. It is one independently measured post-exposure property on its declared basis. The exposure route, other required properties, representative real-use validation and service-life decision remain separate.
07Does this guide prove LayerSource supplies or tests colour-controlled film?+
No. This editorial evidence map identifies no LayerSource grade, inventory, supplier relationship, instrument, laboratory, testing, inspection, colour target, result, certification, appearance promise or supply capability.