Determination method of dry and wet paint film thickness

Film thickness is a key control indicator during Coating production, inspection and construction. It directly affects the uniformity of Coating Spreaders, coating performance and mass painting. In this article, we will discuss the importance of film thickness and various measurement methods to ensure that Coatings meet the required thickness requirements in different applications.

Importance of film thickness

In the Coating industry, the control and determination of film thickness is crucial. The thickness of the film directly affects the performance of the coating, such as corrosion resistance, abrasion resistance and weathering resistance. Coatings that are too thin may not provide adequate protection, and coatings that are too thick may lead to Coating waste and performance problems. Controlling film thickness ensures conformity and mass stability during the painting process. This is essential for Coating manufacturers and the painting industry to avoid Coating mass failure and painting mass problems. The determination of film thickness helps to check the spreading rate of Coating, which is the amount of Coating applied per unit area. This is essential to control Coating cost and resource utilization. In some applications, film thickness must meet specific design requirements. For example, in the aerospace sector, Coating thickness may be limited by strict specifications and standards.

Determination of wet film thickness

The determination of wet film thickness is to check the spreading rate during Coating construction and to ensure the total dry-film thickness of the film after construction. The wet-film measurement must be carried out immediately after the film is prepared to avoid the film cissing phenomenon caused by the evaporation of volatile solvents. The following is an example of a commonly used wet film thickness measurement method:

Thickness Wheel Method:

The principle of this method is to use an instrument composed of three concentric wheels, in which the middle wheel is eccentric with the outer two wheels, with a height difference, and the outer wheel has a scale to indicate the reading of different gaps. The test operation involves holding the Thickness Wheel by clamping the axle with the thumb and index finger, and pressing the concentric rim on the surface by contacting the maximum reading on the scale with the surface. Then roll the Thickness Wheel in one direction, pick the Thickness Wheel up from the surface, and read the maximum reading that the eccentric rim can still be Cowetting scale. The result of wet film thickness can be obtained by calculating the arithmetic mean of these readings.

Determination of dry-film thickness

Dry-film thickness measurement is to ensure that the Coating reaches the desired thickness after drying. There are a variety of instruments and methods that can be used to determine dry-film thickness, here are some examples of them:

Destructiveness measurement:

This method includes magnetic measurement method, eddy current measurement method and β-ray backscattering method. Among them, the magnetic measurement method uses the principle of electromagnetic field magnetoresistance to measure the coating thickness by measuring the Magnetic flux of the substrate. These methods usually express the results in μm.

Mechanical Law:

Mechanical methods include micromeler with dial comprator method, indicator table method and Microscope method. Taking the Microscope method as an example, the principle is to cut a V-shaped notch from the film to the base material, and measure the width of the hypotenuse to get the paint film thickness proportionally. The specific operation is to select - a fixed-angle tool, make a V-shaped notch of the coating up to the substrate, and then directly read the actual thickness of each coating from the Microscope with the scale, and the result is expressed in μm.

These methods allow the determination of dry-film thickness without damaging the Coating, ensuring that the Coating meets the design requirements after drying.

The determination of film thickness is a key link in the Coating industry, which is directly related to the performance and mass of coatings. By choosing a suitable measurement method and making measurements according to the requirements of a specific application, it is possible to ensure that the film reaches the required thickness to meet design and performance standards. In Coating manufacturing and applications, accurate determination of film thickness is one of the key steps to ensure coating mass and performance.