Coating varnishes transparency test

Transparency is a measure of a substance's ability to transmit light. In the production process of coatings, varnishes, clear oils, etc., transparency is a crucial attribute, which not only affects the appearance quality of the product, but also directly relates to the performance of the product. In this article, we'll explore the importance of transparency in the production process and the commonly used methods for detecting transparency.

The importance of transparency

The quality of transparency is a direct reflection of the presence of mechanical impurities and suspensions in the product. The presence of these impurities and suspensions can affect the cosmetic quality of the product, giving it a cloudy and opaque character. This not only reduces the product's shine and color, but also affects its adhesion and resistance to chemical media, reducing the overall performance of the product.

Transparency detection methods

Visual inspection

This is a common method of transparency detection. The principle is to compare the transparency of the specimen under transmitted light. In accordance with the provisions of GB/T 1721-2008 "Determination of the Appearance and Transparency of Varnishes, Clear Oils and Diluents", the specimens were packed in a colorimetric tube with a capacity of 25mL and compared with a series of standard solutions with different turbidity degrees at a temperature of (23±2) °C. The results are usually expressed in three grades: transparent, slightly cloudy, and cloudy, i.e., grade 1, grade 2, and grade 3.

Instrumentation method

A photoelectric Turbidity Meter is used for measurement to eliminate the interference of different hues of the product on the visual inspection results and improve the accuracy of the test. The light emitted by the light source in the instrument is scattered by the influence of impurities or suspended solids in the test tube, which is reflected by the reflector and projected onto the photoresistor before being received. A frosted plexiglass rod with a refractive index of approximately 1.5 is usually used to set the standard turbidity of 100, zeroed with distilled water, and then the sample is measured, and the results are expressed as numbers.

Transparency is an indispensable key factor in the production of coatings, varnishes, clear oils, etc. Through transparency testing, we can find impurities and suspensions in products in time, and take corresponding measures to ensure the quality and performance of products. Therefore, the control and monitoring of transparency is of great importance in the production process.