How to Measure Specular Gloss of Nonmetallic Specimens with ASTM D523-89
Specular gloss is a measure of how shiny a surface is, or how much it reflects light in the mirror direction. It is important for evaluating the appearance and quality of various materials, such as paints, coatings, plastics, paper, ceramics, and textiles. Specular gloss can also affect the perceived color, texture, and distinctness of image of a surface.
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One of the most widely used methods for measuring specular gloss is ASTM D523-89, which is a standard test method developed by ASTM International. This method covers the measurement of the specular gloss of nonmetallic specimens for glossmeter geometries of 60, 20, and 85 degrees. A glossmeter is an instrument that measures the amount of light reflected by a surface at a specified angle and compares it to a standard reference material, usually black glass.
The 60-degree geometry is used for intercomparing most specimens and for determining when the 20-degree geometry may be more applicable. The 20-degree geometry is advantageous for comparing specimens having 60-degree gloss values higher than 70. The 85-degree geometry is used for comparing specimens for sheen or near-grazing shininess. It is most frequently applied when specimens have 60-degree gloss values lower than 10.
To perform the test, the specimen and the standard are placed on a flat surface and aligned with the glossmeter. The glossmeter is calibrated with the standard and then moved to measure the specimen. The glossmeter displays the specular gloss value of the specimen as a percentage of the standard. The higher the percentage, the shinier the surface.
The test method also specifies the preparation of specimens, such as cleaning, drying, conditioning, and applying uniform films of paint or coating. The test method also provides guidelines for reporting and interpreting the results, such as averaging multiple readings, calculating standard deviations, and comparing gloss values within and between laboratories.
The test method can be downloaded as a PDF file from ASTM International's website or from other online sources. The PDF file contains detailed instructions, diagrams, tables, references, and appendices for conducting the test method.
Specular gloss measurement has many benefits and applications in various industries and fields. For example, gloss measurement can help to control the quality and consistency of products, such as paints, coatings, plastics, paper, ceramics, and textiles. Gloss measurement can also help to evaluate the performance and durability of materials, such as their resistance to abrasion, weathering, corrosion, and chemical attack. Gloss measurement can also help to optimize the production process and reduce costs by adjusting the formulation, application, and curing of materials. Gloss measurement can also help to enhance the aesthetic appeal and customer satisfaction of products by matching the desired gloss level and appearance.
Some examples of specific applications of specular gloss measurement are:
Gloss measurement can help to determine the effect of pigment concentration, type, and grade on the stability and appearance of paints and coatings [1].
Gloss measurement can help to evaluate the binder durability and film formation of paints and coatings [1].
Gloss measurement can help to assess the effect of proportion between the pigment and the extender on the hiding power and opacity of paints and coatings [1].
Gloss measurement can help to monitor the curing process and degree of cross-linking of thermosetting resins [2].
Gloss measurement can help to measure the surface smoothness and uniformity of plastics and films [2].
Gloss measurement can help to detect surface defects and scratches on plastics and films [2].
Gloss measurement can help to classify paper grades according to their brightness, whiteness, and smoothness [3].
Gloss measurement can help to measure the effect of calendaring, coating, and finishing on paper quality [3].
Gloss measurement can help to measure the surface roughness and texture of ceramics [4].
Gloss measurement can help to evaluate the glazing and firing process of ceramics [4].
Gloss measurement can help to measure the color change and fading of textiles due to washing, bleaching, dyeing, or exposure to light [5].
Gloss measurement can help to measure the softness and smoothness of textiles [5].
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