Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
SIGNIFICANCE AND USE 5.1 The most direct and accessible methods for obtaining the color coordinates of object colors are by instrumental measurement using spectrophotometers or colorimeters with either hemispherical or bidirectional optical measuring systems. This test method provides procedures for such measurement by reflectance spectrophotometry using a hemispherical optical measuring system. 5.2 This test method is especially suitable for measurement of the following types of specimens for the indicated uses (Guide E179 and Practice E805): 5.2.1 All types of object-color specimens to obtain data for use in computer colorant formulation. 5.2.2 Object-color specimens for color assessment. 5.2.2.1 For the measurement of plane-surface high-gloss specimens, the specular component should generally be excluded during the measurement. 5.2.2.2 For the measurement of plane-surface intermediate-gloss specimens and of textured-surface specimens, including textiles, where the first-surface reflection component may be distributed over a wide range of angles, measurement may be made with the specular component included, but the resulting color coordinates may not correlate best with visual judgments of the color. The use of bidirectional geometry, such as 45/0 or 0/45, may lead to better correlations. 5.2.2.3 For the measurement of plane-surface, low-gloss (matte) specimens, the specular component may either be excluded or included, as no significant difference in the results should be apparent. 5.2.3 Specimens with bare metal surfaces for color assessment. For this application, the specular component should generally be included during the measurement. 5.3 This test method is not recommended for measurement of the following types of specimens, for which the use of bidirectional measurement geometry (0/45 or 45/0) is preferable (Guide E179): 5.3.1 Object-color specimens of intermediate gloss, 5.3.2 Retroreflective specimens, and 5.3.3 Fluorescent specimens (Practice E... SCOPE 1.1 This test method describes the instrumental measurement of the reflection properties and color of object-color specimens by the use of a spectrophotometer or spectrocolorimeter with a hemispherical optical measuring system, such as an integrating sphere. 1.2 The test method is suitable for use with most object-color specimens. However, it should not be used for retroreflective specimens or for fluorescent specimens when highest accuracy is desired. Specimens having intermediate-gloss surfaces should preferably not be measured by use of this geometry. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
ASTM E1331-15(2023), titled Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry, is a widely recognized international standard developed by ASTM International. This standard outlines precise procedures for measuring the reflectance properties and color coordinates of object-color specimens using a spectrophotometer or spectrocolorimeter equipped with a hemispherical optical measuring system, such as an integrating sphere.
The method focuses on instrumental evaluation of color and appearance, ensuring consistency and reliability in color measurement across a diverse range of materials. The standard plays a crucial role in quality control, color formulation, and product development across multiple industries.
ASTM E1331 is highly valuable across industries where objective color measurement and comparison are crucial:
Другие стандарты ASTM
While suitable for most opaque and translucent samples with plane surfaces, the method is not recommended for retroreflective or fluorescent materials where the highest accuracy is required, nor for intermediate-gloss surfaces where bidirectional geometry may be preferable.
Several ASTM standards complement the use of ASTM E1331, supporting comprehensive color and appearance measurement:
Adopting ASTM E1331-15(2023) ensures rigor and repeatability in the measurement of reflectance factor and color by spectrophotometry using hemispherical geometry. The standard enhances inter-laboratory consistency, product quality, and color matching capability, providing a foundation for reliable color communication in manufacturing and research environments. For organizations and professionals dedicated to precise color control, this standard is indispensable.