Significance and Use
This practice should be used only to compare specimens of the same material and same general appearance. For example, a series of specimens to be compared should have generally similar gloss, texture, and (if not opaque) thickness, and translucency.
For yellowness measurement, this practice is limited to specimens having dominant wavelength in the range 570 to 580 nm, or Munsell hue approximately 2.5GY to 2.5 Y. For whiteness measurement, this practice is limited to specimens having Munsell value greater than 8.3 (CIE Y greater than 65) and Munsell chroma no greater than 0.5 for B hues, 0.8 for Y hues, and 0.3 for all other hues (see 3.3.1).
The combination of measurement and calculation leading to indices of yellowness or whiteness is a psychophysical process, that is, the procedures specified are designed to provide numbers correlating with visual estimates made under specified typical observing conditions. Because visual observing conditions can vary widely, users should compare calculated indices with visual estimates to ensure applicability. Some standards addressing the visual estimation of color and color difference are Practices D1535, D1729, E1360, and E1541, and Guide E1499.
This practice does not cover the preparation of specimens, a procedure that may affect significantly the quantities measured. In general, specimens should be prepared and presented for measurement in the manner that is standard for the test being performed. Select enough specimens or specimen areas to provide an average result that is representative of each sample to be tested. See Practice E1345.
1.1 This practice provides numbers that correlate with visual ratings of yellowness or whiteness of white and near-white or colorless object-color specimens, viewed in daylight by an observer with normal color vision. White textiles, paints, and plastics are a few of the materials that can be described by the indices of yellowness or whiteness calculated by this practice.
1.2 For a complete analysis of object colors, by a specified observer and under a specified illuminant, use of three parameters is required. For near-white specimens, however, it is often useful to calculate single-number scales of yellowness or whiteness. This practice provides recommended equations for such scales and discusses their derivations and uses, and limits to their applicability (see also Ref (1) ).
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D1535 Practice for Specifying Color by the Munsell System
D1729 Practice for Visual Appraisal of Colors and Color Differences of Diffusely-Illuminated Opaque Materials
D1925 Test Method for Yellowness Index of Plastics
E284 Terminology of Appearance
E308 Practice for Computing the Colors of Objects by Using the CIE System
E805 Practice for Identification of Instrumental Methods of Color or Color-Difference Measurement of Materials
E991 Practice for Color Measurement of Fluorescent Specimens Using the One-Monochromator Method
E1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation
E1247 Practice for Detecting Fluorescence in Object-Color Specimens by Spectrophotometry
E1331 Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
E1345 Practice for Reducing the Effect of Variability of Color Measurement by Use of Multiple Measurements
E1347 Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
E1348 Test Method for Transmittance and Color by Spectrophotometry Using Hemispherical Geometry
E1349 Test Method for Reflectance Factor and Color by Spectrophotometry Using Bidirectional (45:0 or 0:45) Geometry
E1360 Practice for Specifying Color by Using the Optical Society of America Uniform Color Scales System
E1499 Guide for Selection, Evaluation, and Training of Observers
E1541 Practice for Specifying and Matching Color Using the Colorcurve System
color; colorimetric analysis; color/light; instrumental measurement; reflectance; reflectivity; whiteness indexes; yellowness indexes; Ceramic materials/applications; Color; Color--opaque materials; Colorimetric analysis; Instrumental measurement--color/light; Latex paints; Opacity/opaque materials; Paint testing; Paper; Psychophysical examination; Reflectance and reflectivity--paints/related coatings/materials; Solventborne paints/coatings; Spectral data--paints/related coatings; Spectrophotometry; Textile fabrics (general); Textile fibers; Tristimulus value; Visual examination--color; Whiteness index; Yellowness index;
ICS Number Code 17.180.20 (Colours and measurement of light)
ASTM International is a member of CrossRef.
Citing ASTM Standards
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