The test results of coatings properties of color coated sheets are closely related to the correctness of sampling. The national standard GB318682 specifies specific sampling methods, which are as follows:
(1) Random sampling from each batch of products is 3% of the total number of packaging barrels of the same manufacturer (batch less than 100 barrels, not less than 3 barrels; batch less than 4 barrels, not less than 30%).
(2) When sampling, open the lid of the barrel, observe the paint products of the liquid color coated sheet in the barrel visually, and record the surface state, such as whether there is crust, precipitation, stratification and other phenomena.
(3) Mix the paint evenly in the barrel, and take no less than 0.5 kg of samples per barrel. Divide the samples into two parts (about 0.4 kg) for sealed storage for inspection, and the other part for immediate inspection. If the test results do not meet the required value of the standard, the whole batch of products will be considered unqualified.
(4) Clean the sampling tube after use. Samples should not be filled with containers. 5% of the space should be reserved and sealed. Samples should be placed in clean, dry and sealed metal cans or glass bottles, labeled, date of sampling and other related details, and stored in a cool and dry place.