The standard "ASTM D1003-21 Standard test method for haze and light transmission of transparent plastics" published by the American Society for Testing and Materials (ASTM) describes a test method for evaluating specific light transmission and wide-angle light scattering properties of planar sections of materials such as transparent plastics.
This standard provides two procedures for measuring light transmittance and haze. Procedure A uses a haze meter, while Procedure B uses a spectrophotometer. Material with a haze value greater than 30 percent is considered diffusive and should be tested in accordance with “ASTM E2387-19 Standard Practice for Goniometric Optical Scattering Measurements.”
For the purposes of this standard, in addition to the terms and definitions given in ASTM D883 and ASTM E284, the following definitions apply:
Light scattered through a layer of film or material can produce a hazy or smoky area when objects are viewed through the material. Another effect might be to hide the glare on a car windshield when driving into the sun.
Haze measurements are most commonly made using a haze meter, although a spectrophotometer may be used provided it meets the geometric and spectral requirements of this standard. The use of a spectrophotometer for haze measurement of plastics can provide valuable diagnostic data on the origin of the haze, and Procedure B is devoted to the use of a spectrophotometer. Procedure A (haze meter) test values are normally slightly higher and less variable than Procedure B (spectrophotometer) test values.
The regular light transmittance is obtained by placing a clear sample at a certain distance from the inlet port of the integrating sphere. However, when the sample is turbid, the total hemispherical light transmittance should be measured by placing the sample at the inlet port of the sphere. The measured total hemispherical light transmittance will be greater than the regular light transmittance, depending on the optical properties of the sample. In this test method, the sample must necessarily be placed at the inlet port of the sphere to measure turbidity and total hemispherical light transmittance.
Haze data representative of the material can be obtained by avoiding heterogeneous surface or internal defects that are not characteristic of the material. Haze and light transmittance data are particularly useful for quality control and specification purposes.
Before proceeding with this test method, the specification for the material being tested should be consulted. Any test specimen preparation, conditioning, dimensions or test parameters or combination thereof included in the material specification shall take precedence over those specified in this test method. In the absence of a material specification, the default conditions shall apply.
Sampling should be statistically sufficient to ensure that samples have been obtained and produced by a process in which statistical control is exercised. Samples should be obtained free from defects not characteristic of the material, provided that these defects do not constitute the variables under study.
Each test specimen is cut to a size large enough to cover the inlet port of the sphere. A 50 mm diameter disk or a square with sides of the same dimensions is recommended. The specimen should have substantially flat, parallel surfaces, free from dust, grease, scratches and blemishes, and should be free from visibly visible internal voids and particles unless it is desired to specifically measure the contribution to haze from these defects.
Unless otherwise specified in the applicable material specification, three samples are prepared for testing each sample of a given material. Sample type and preparation may affect the actual turbidity of the materials tested.
Unless otherwise required by the applicable material specification or agreed upon between the customer and the supplier, test specimens shall be conditioned in accordance with Procedure A of ASTM D618-21 Standard Practice for Preparation of Plastics for Testing at 40 degrees plus/minus 23 degrees and 2 percent plus/minus 50 percent relative humidity for at least 10 hours prior to testing. In case of disagreement, tolerances shall be plus/minus 1 degree and plus/minus 5 percent relative humidity. The test apparatus shall be installed in an atmosphere maintained at 23 degrees plus/minus 2 degrees and 50 percent plus/minus 10 percent relative humidity.
The following two test methods are described in detail in this standard:
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