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ASTM D1925 -Standard Testing Instruments
Yellowness index (YI) is a standard test (ASTM D1925) that was developed to determine the value of the yellowness index of plastic materials (transparent, translucent, or opaque). The yellowness index measures the extent of deviation of a material from colorless or white towards yellow color, which is one of the indicators of the degradation of materials or the exposure to UV radiation. It is used throughout the packaging industry, as well as the automotive, consumer goods, and polymer manufacturing sectors, for color appearance and consistency measurement.
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Significance
The importance of ASTM D1925 is that it identifies early degradation of color for plastic materials from heat exposure, light exposure, oxidation, and/or chemical aging. Manufacturers can use the precise measurement of the yellowness values to pinpoint quality deviations, ensure visual uniformity, and optimize production methods. It is an effective tool to gain confidence in the consistency of batches, verify raw materials, and ensure final products align with the optical appearance targets that customers and regulatory authorities demand.
Scope
ASTM D1925 is used on a variety of plastic materials such as films, sheets, molded parts, and polymer products. Inevitably, spectrophotometric measurements are used in the test carried out under laboratory control conditions to calculate the yellowness index. It is suitable for solid types of samples as well as film forms and can be used in the framework of quality inspection programs in numerous industry sectors, where stability and color appearance of the samples are among the key parameters.