introduction
In the field of coating, the appearance characteristics of paint films are one of the important indicators for evaluating coating quality. In addition to gloss and color, haze is also a key characterizing property, especially for high-gloss coatings. This article will introduce the definition of haze, related standards, and the paint film haze measurement method specified in the ISO 13803 standard.
The purpose and significance of paint film haze measurement
Haze refers to the diffuse reflection phenomenon produced by the surface of a high-gloss coating film when it is illuminated by light. The ISO 13803 standard clarifies the measurement range of haze: it is suitable for coatings with a gloss value of 90 units or more (20° gloss). The purpose of haze measurement is to evaluate the surface diffuse reflection of high-gloss coatings as a basis for evaluating the quality of the coating.
Related standards
The ISO 13803:2000 standard specifies a method for the determination of 20° haze in paint films of tinted paints and varnishes. This standard provides an accurate and repeatable method for determining haze to ensure consistency and standardization of coating quality.
Paint film haze measurement method
Test principle
The haze measurement method described in the ISO 13803 standard measures the haze of a paint film by receiving scattered light from reflected light from both sides at an angle close to 20°. This method accurately evaluates the diffuse reflection of high-gloss coatings at different angles.
Operational points
Preparation of the test plate: Use a wet film preparer with a specification of 150 μm to apply the color paint on a clean glass plate to ensure that the paint film is smooth.
Haze determination: Three readings are measured on the test paint film at different locations parallel to the coating direction. If the error is less than 0.5 units, record the average value as the linear haze value. Otherwise, perform three more measurements and record the average and limit values ââof all six values.
For coatings on non-glass substrates: After adjusting and calibrating the instrument, measure six times in different areas or directions on the sample surface (excluding cases with texture directions on the surface such as brush marks, etc.), and record the average value. If the error of the six measurement results is less than 1 unit value or 20% of the average value, record the average value and limit value. Otherwise, discard the test panel.
Result expression
According to the ISO 13803 standard, the average linear haze value can be used to represent the haze of the paint film. It can also be agreed upon to use the logarithmic mean of the haze as a representation.
Meaning and application
The determination of paint film haze is of great significance in evaluating the quality of high-gloss coatings. For coatings with high decorative requirements, such as automotive coatings, haze is one of the important indicators to measure their appearance quality. The results of the haze measurement can help formulate a reasonable grinding and dispersion time, select appropriate additives and additive concentrations to ensure the high quality and consistency of the coating.
in conclusion
In the field of coating, haze, as an important characteristic property, is crucial to the appearance quality of high-gloss coatings. The ISO 13803 standard provides an accurate method to evaluate the haze of coatings by measuring the scattered light in reflected light from both sides at an angle close to 20°. The application of this method helps the coating industry ensure consistent and high-quality product appearance. At the same time, paint film haze measurement also provides a scientific basis for adjusting process parameters and optimizing formulas, thereby improving coating quality and customer satisfaction.
