What are the requirements for atmospheric exposure field samples?

       The sample used for the atmospheric exposure test, the sheet sample uses a steel plate (or other metal plate) with a specification of 50mmx100mmx(1~2)mm as the base. The size of the finished sample is not limited, but the exposure should be placed with the major surface up and facing south. Each sample should have a serial number that is not easy to disappear, and can be stamped with a steel stamp or a name plate.



    (1) The samples can be exposed all year round, but if the same batch of samples are tested in exposure fields in different regions, the test time should be the same.

    (2) Before the test, use a special record card to record the number, coating structure, thickness, appearance gloss and other items of the sample, and write the test outline (including test purpose, requirements, inspection cycle, etc.). One to three pieces of each sample should be kept in a desiccator for comparison and observation during the test.

    (3) During the first 3 months of exposure, the samples should be inspected frequently, such as 2 or 3 times a month, and the time when the corrosion spots began to appear should be noted and recorded on the record card. After 3 months, the number of inspections can be reduced to once a month, and after a year, it can be inspected once every 3 months.

    (4) For samples exposed in winter, in case of snow, the snow on the surface of the samples should be brushed off regularly.

    (5) Do not use your fingers to contact the main surface of the sample when taking the sample (the sheet sample can only take its edge, and the irregular shape parts can only take its non-main surface). Two-piece testing is not allowed. The samples overlap and rub against each other to avoid errors caused by mechanical damage.

    After the coating is exposed to the atmosphere, the qualitative evaluation of the test results can be observed with the naked eye or a magnifying glass (3 times to 5 times), and sometimes some simple tools and equipment can be appropriately used. The corrosion products of various coatings in the atmosphere have unique symptoms (such as color, shape, etc.). From these corrosion products and their changes, the degree of corrosion of the coating or base metal can be judged to determine its protective performance. .