Astm D523 89 Pdf Download
ASTM D523-89: A Standard Test Method for Specular Gloss
Specular gloss is a measure of how shiny a surface is, or how well it reflects light in the mirror direction. It is important for many applications, such as paints, coatings, plastics, metals, and ceramics, where the appearance and quality of the surface are critical. Specular gloss can also affect the perception of color, texture, and shape of an object.
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ASTM D523-89 is a standard test method for measuring the specular gloss of nonmetallic specimens using a glossmeter with three different geometries: 60, 20, and 85 degrees. The test method was developed by ASTM International, an organization that provides standards for materials, products, systems, and services. ASTM D523-89 was first published in 1939 and has been revised several times since then. The latest edition was approved in 2008.
How does ASTM D523-89 work?
The test method is based on comparing the luminous reflectance factor of a specimen to that of a polished black glass standard under the same geometric conditions. The luminous reflectance factor is the ratio of the light reflected from a surface to the light reflected from a standard surface. The black glass standard has a known reflectance factor that is close to 100% for all angles of incidence.
The glossmeter consists of a light source, a receptor, and an indicator. The light source emits a beam of light that strikes the specimen at a specified angle. The receptor measures the amount of light that is reflected from the specimen in the mirror direction. The indicator displays the gloss value as a percentage of the reflectance factor of the black glass standard.
The test method uses three different angles of incidence: 60, 20, and 85 degrees. These angles are chosen to cover a wide range of gloss levels and to suit different types of specimens. The 60-degree angle is used for most specimens and for determining when the 20-degree angle may be more applicable. The 20-degree angle is advantageous for comparing specimens with high gloss values (above 70 at 60 degrees). The 85-degree angle is used for comparing specimens with low gloss values (below 10 at 60 degrees) or for measuring sheen or near-grazing shininess.
How to perform ASTM D523-89?
The test method requires some preparation and calibration steps before measuring the specular gloss of a specimen. These steps include:
Selecting a suitable glossmeter geometry according to the expected gloss level of the specimen.
Preparing the specimen according to the relevant ASTM practices, such as D823, D3964, or D4039.
Calibrating the glossmeter using the black glass standard and verifying its accuracy and stability.
Cleaning the specimen and placing it on a flat and horizontal surface.
Aligning the glossmeter with the specimen so that the light beam strikes the specimen perpendicularly.
Reading and recording the gloss value displayed by the indicator.
Repeating the measurement at least three times on different areas of the specimen and averaging the results.
What are the advantages and limitations of ASTM D523-89?
ASTM D523-89 is a widely used and accepted test method for measuring specular gloss. It has several advantages, such as:
It is simple, fast, and easy to perform.
It provides objective and quantitative results that correlate well with visual observations.
It covers a broad range of gloss levels and types of specimens.
It is compatible with other ASTM standards and international standards, such as ISO 2813.
However, ASTM D523-89 also has some limitations, such as:
It does not account for other factors that may affect gloss perception, such as surface texture, color, shape, lighting conditions, and viewing angle.
It may not be suitable for some specimens that have irregular shapes, rough surfaces, or directional properties.
It may not be sensitive enough to detect small differences in gloss levels or to measure very low or very high gloss values.
It may be influenced by the quality and condition of the glossmeter and the specimen.
Where can I find more information about ASTM D523-89?
If you are interested in learning more about ASTM D523-89, you can download the full text of the standard from the ASTM website . You can also find other related standards, such as ASTM E97, ASTM E430, and ASTM D3980, that provide additional methods and guidance for measuring gloss and appearance. Furthermore, you can consult various publications and articles that discuss the theory, application, and interpretation of specular gloss measurements.