The difference in the preparation of the salt spray test chamber samples greatly affected the reproducibility of the test results of the prepainted galvanized steel coil in stock. Therefore, you should pay attention to the correct treatment method, or adopt a processing mode negotiated by both parties to reduce the difference of test results. The main points worth noting are the following two points:
Surface quality: During the sampling or sample preparation process, the coating should be scratched or the surface should have obvious defects, which will affect the test results.
Scratch condition: When the color-coated sample is broken, the selection of the scribing tool, the depth and geometry of the scratch will affect the test results. Therefore, it is especially important to use a special scribing tool.
For the depth of the scratch, the provisions in both standards require that the coating be scratched. Since most of the substrates used in the cheap PPGI prepainted galvanized steel coil is hot-dip galvanized sheet, the galvanized layer can be drawn according to standard requirements without special provisions. However, in the operation, since the scale is not well controlled, it is recommended to adopt a method of negotiating by both parties, and the scratch depth is defined as penetrating the plating layer so that the scribe line is a uniform bright line without burrs to avoid scribe lines. Different conditions have an impact on the consistency of test results.