Plastics Technology Laboratories  

Yellowness Index


Click on the picture for a larger view

Yellowness Index is a number calculated from spectrophotometric data that describes the change in color of a test sample from clear or white toward yellow. This test is most commonly used to evaluate color changes in a material caused by real or simulated outdoor exposure.

Test Procedure:
Test sample packaging, handling, and preparation (preferably no cleaning) can affect the test results by modifying the surface of the sample. Since YI testing is often a series of comparative measurements over extended periods of time, these factors should be defined and documented prior to any testing.

The BYK Gardner Spectrophotometer is highly automated. After specifying the illuminant, observer angle, and the reference color, the test sample is inserted into the specimen holder, and the spectrophotometer takes the reading. Multiple samples should be measured and the readings averaged.

Specimen size:
Typically a 4" (100 mm) disk, although any flat sample that the specimen holder will grasp can be tested.

Yellowness Index (YI)

Equipment Used:
BYK Gardner Spectrophotometer

Intertek PTL Overview
Contact Us
Services & Tech Info
Industry Segments
Industry Segments


**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For more information please contact a Intertek PTL Technical Representative at . Due to copyright restrictions, we are not able to provide copies of standards. Standards can be obtained from appropriate standards authorities.

Back to Testlopedia