ASTM E313: Yellowness Index Testing Services
Accredited ASTM E313 yellowness index testing from Infinita Lab, performed to the exact standard requirements - accurate, reproducible results with full documentation for compliance, R&D, and quality control programs.
TRUSTED BY
Get ASTM E313 compliant results - request your yellowness index testing quote
- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
What Is ASTM E313 Yellowness Index?
ASTM E313, Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Colour Coordinates, is a calculation practice rather than a colour measurement method in itself. It defines how to convert tristimulus colour coordinates, X, Y, and Z, measured separately by a spectrophotometer or colourimeter, into single-number Yellowness Index (YI) and Whiteness Index (WI) values that correlate with how a trained observer would visually judge a white or near-white specimen. The tristimulus values used as input are obtained under standardised illuminant and observer conditions, most commonly CIE Illuminant C with the 2-degree observer or Illuminant D65 with the 10-degree observer, following the colorimetric procedures described in companion standards such as ASTM E308. ASTM E313 then applies defined formulas, using illuminant- and observer-dependent coefficients, to calculate a yellowness value from the weighted difference between the X and Z tristimulus values relative to Y, and a whiteness value from the specimen’s Y, x, and y coordinates relative to a perfect reflecting diffuser, producing a single comparable number in place of a full spectral curve or three-dimensional colour coordinate set. This matters because it gives manufacturers a fast, objective way to track subtle colour shifts that would otherwise require visual comparison or interpretation of full Lab or XYZ data. Plastics, coatings, textiles, and paper products are prone to yellowing or loss of whiteness from UV exposure, heat aging, and oxidation, and even small changes can affect perceived quality and brand consistency. By reducing colour change to a single, repeatable value, ASTM E313 supports quality control, material qualification, weathering studies, and batch-to-batch comparisons. Infinita Lab’s accredited partner laboratory network applies ASTM E313 calculations to instrumentally measured colour data to help manufacturers monitor yellowing and whiteness trends, validate UV and heat stability, and document colour performance with objective, standardised data.
Applications and Benefits of ASTM E313 Yellowness Index Testing
Scope
- Provides standardised formulas for calculating a Yellowness Index (YI) and a Whiteness Index (WI) from instrumentally measured tristimulus colour coordinates.
- Depends entirely on tristimulus X, Y, and Z values that are measured separately using a spectrophotometer or colorimeter, since the practice itself performs no direct colour measurement.
- Requires that tristimulus values be obtained under defined illuminant and observer conditions, typically CIE Illuminant C/2-degree observer or D65/10-degree observer, so that the correct calculation coefficients can be applied.
- Applies to white, near-white, and colourless object-colour specimens, including plastics, coatings, textiles, paper, and other materials where yellowing or whiteness is a meaningful quality attribute.
- Limits yellowness calculations to specimens whose colour falls within a defined range of dominant wavelength or Munsell hue, and limits whiteness calculations to specimens meeting minimum lightness and low-chroma criteria.
- Supports industries including plastics and polymer manufacturing, textiles, paper and packaging, coatings and paints, and consumer products where whiteness or resistance to yellowing is a specification requirement.
- Is commonly used alongside related colorimetric standards, such as ASTM E308 for computing tristimulus values from spectral data and ASTM D2244 for colour difference calculation, as part of a broader colour measurement program.
- Serves as the calculation basis for tracking discolouration caused by UV exposure, heat aging, oxidation, and other weathering or aging mechanisms.
- Supports quality control, material qualification, and comparative studies by expressing complex color data as a single, repeatable index value rather than requiring interpretation of full spectral or three-dimensional colour data.
- Provides testing that underpins specification compliance, supplier qualification, and product development decisions where consistent whiteness or resistance to yellowing is required.
Applications
- Aging and weathering studies on plastics and polymers exposed to UV light, heat, or outdoor conditions to track the onset and rate of yellowing.
- Whiteness and yellowing monitoring for textiles, including fabrics, fibres, and finished garments subject to bleaching, dyeing, or use-related discolouration.
- Whiteness assessment of paper, pulp, and packaging materials where brightness and colour consistency affect perceived quality.
- Quality control screening for white or near-white plastic, coating, and consumer product batches to detect colour drift during manufacturing.
- UV stability testing of coatings and plastic components used in outdoor, automotive, or architectural applications.
- Comparative evaluation of raw materials, additives, or stabiliser packages to determine their effect on long-term colour retention.
- Verification of colour specification compliance for incoming materials, in-process products, and finished goods before shipment.
Benefits
- Converts complex tristimulus or spectral colour data into a single, easy-to-communicate yellowness or whiteness value.
- Provides an objective, repeatable alternative to subjective visual comparison of white or near-white specimens.
- Enables straightforward tracking of colour change over time, supporting weathering, aging, and stability studies.
- Supports consistent supplier qualification and incoming material screening using standardised, comparable index values.
- Facilitates clear pass/fail or trend-based quality decisions tied to defined specification limits.
- Integrates readily with existing spectrophotometric or colour measurement workflows already used for colour quality control.
Our ASTM E313 Testing Procedure
Sample Preparation
The test specimen is cleaned and prepared with a smooth surface for accurate color measurement.
1Instrument Calibration
A spectrophotometer or colorimeter is calibrated using standard reference materials.
2Color Measurement
The instrument measures tristimulus values of the sample under controlled lighting conditions.
3Yellowness Index Calculation
The yellowness index is calculated from the measured color values using the ASTM E313 formula.
4ASTM E313 Test Parameters and Requirements
| Parameter | Details |
|---|---|
| Material Tested | Plastics, coatings, paper, textiles, and other light-colored materials. |
| Test Principle | Measurement of colorimetric values to determine yellow coloration. |
| Measurement Method | Spectrophotometric color measurement. |
| Key Parameter | Yellowness Index (YI). |
| Measurement Basis | Tristimulus color values (X, Y, Z). |
| Testing Environment | Controlled lighting and laboratory conditions. |
| Application Relevance | Important for color stability and quality control. |
- Spectrophotometer or Colourimeter – Measures the specimen’s reflected or transmitted light to generate the tristimulus X, Y, Z colour coordinates used as the calculation input.
- Certified White and Black Reference Standards – Used to calibrate and verify instrument accuracy before and during colour measurement.
- Sample Holder or Presentation Fixture – Positions the specimen consistently at the instrument’s measurement port to ensure repeatable readings across replicates.
- Calculation and Reporting Software – Applies the ASTM E313 formulas and illuminant-specific coefficients to the measured tristimulus data and compiles the resulting index values into a report.
- Controlled Lighting Booth – Provides standardised daylight-simulating illumination for visual cross-checking of specimens alongside the instrumental index values.
- Environmental Conditioning Equipment – Maintains specimens at controlled temperature and humidity before measurement to minimise environmental influence on colour readings.
Equipment and Instrumentation Used for ASTM E313 Testing
What You Receive: Test Report, Data, and Certification
- Calculated Yellowness Index (YI) and/or Whiteness Index (WI) values for each tested specimen.
- Documentation of the tristimulus colour coordinates, illuminant, and observer conditions used in the calculation.
- Comparison of calculated index values against reference specimens, specification limits, or historical data where applicable.
- Identification of any specimen characteristics that fall outside the applicability limits defined in ASTM E313.
- Supporting notes on measurement conditions, instrument calibration, and specimen preparation.
- A formal, accredited test report suitable for specification compliance, supplier qualification, and internal quality records.
ASTM E313 Yellowness Index FAQs
ASTM E313 Yellowness Index refers to the degree of yellowness in white or whitish materials. This test is valuable in evaluating color changes brought about by aging or chemical damage.
YI is a significant parameter for evaluating materials' color quality and stability when exposed to sunlight and other environmental factors. It helps the manufacturers achieve the color of their products per the general specifications of any particular industry while retaining their color appearance over a considerable period.
The Yellowness Index is measured using a spectrophotometer or colorimeter, which analyzes a material sample's reflected or transmitted light. The instrument calculates the YI value based on the material's spectral data, comparing it to the standard reference value.
YI testing is usually used to control the quality of plastic packaging, paper, textiles, paints, and coatings since it enables monitoring of yellowing upon aging.
A higher YI value indicates greater yellow coloration or increased discoloration of the material.
The Yellowness Index (YI) quantifies the degree to which a white, near-white, or colourless material appears yellow. Colour coordinates are measured instrumentally, and the resulting CIE tristimulus values are used to calculate a numerical YI.
ASTM E313 calculates yellowness and whiteness indices from instrumentally measured colour coordinates. A colour-measuring instrument obtains the specimen’s tristimulus values, which are then used with the applicable ASTM equations and illuminate/observer conditions to calculate the index.
A yellow test measures the color of a specimen using a spectrophotometer or colorimeter and calculates its Yellowness Index. The resulting value can be used to compare yellowing among similar materials, such as plastics, paints, textiles, and other near-white products.
Why Choose Infinita Lab for Yellowness Index Testing
When your Yellowness Index results have to hold up - for compliance, a customer audit, or an engineering decision - ASTM E313 accuracy and an unbiased third-party report matter more than price. Infinita Lab routes your ASTM E313 yellowness index testing to ISO/IEC 17025-accredited U.S. partner labs with hands-on method experience, so you get defensible data, transparent reporting, and turnaround times built around your project deadline - not ours.
Need ASTM E313 Yellowness Index Testing You Can Rely On?
Send query us at hello@infinitalab.com or call us at (888) 878-3090 to learn more about our services and how we can support you.
Request a Quote
Submit your material details and receive testing procedures, pricing, and turnaround time within 24 hours.
Quick Turnaround and Hasslefree process
Confidentiality Guarantee
Free, No-obligation Consultation
100% Customer Satisfaction
