Various methods used to test the coating film in the test room (that is, under artificial conditions). From the results obtained by laboratory tests, it is not always possible to draw conclusions about the suitability of paint materials for use under natural conditions.
Therefore, if the stability of paint materials to atmospheric action is tested under natural conditions, more reliable results will be obtained.
Since most paint materials are used to protect metal and wood from atmospheric action, it is obvious that tests under natural conditions are decisive for determining the corrosion resistance of paint materials. When testing new materials whose properties have not been determined under atmospheric conditions, it is better to also test materials whose properties are known under the same conditions.
Atmospheric action is the sum of many factors: such as humidity, sunlight, temperature drop (cold, hot), trace amounts of carbon dioxide and other gases (the last factor has special significance in industrial centers). Solid particles in the air also affect the stability of the coating film. ,, Among the disadvantages of conducting experiments under natural conditions, the first is that the time required for the experiment is too long. In addition, there are factors such as different climates, test seasons, test locations, etc., which make it impossible to measure the absolute value of the durability of paint materials under natural conditions; Relative data on membrane durability. (Related instruments: aging Test Chamber)
The factors that can ensure the reliability of the coating film under natural (atmospheric) conditions can be divided into three categories: that is, before the sample is exposed, at the time of exposure, and when the degree of damage is evaluated.
Three categories of factors determine the reliability of a test.
The first category includes sample preparation, drying time before exposure, sample size, material and quantity selection, coating layer number and thickness and other factors. (Related instruments: drying time Tester, Thickness Gauge)
Belonging to the second category, there are factors such as the choice of test site, climatic conditions, the influence of weather, the exposure season, the inclination angle between the sample and the horizon, and the purity of the air.
Those belonging to the third category are mainly selected reliable methods for identifying the degree of damage. Based on the above, it can be concluded that only when all factors are taken into account can atmospheric tests obtain reliable results. Rapid testing can ensure more consistent testing conditions than testing under natural conditions.
Although the test under natural conditions has many disadvantages, it is still widely used as the rapid test, and it also plays a decisive role in evaluating the weather resistance of the coating film. The stability of the test coating film under atmospheric conditions should be carried out according to OCT10086-39 test method 38.
