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Color coated coil coating thickness selection

Aug 16,2023

Microscopically, a coating is a hollow tissue. Water in the air, corrosive media (chloride ions, etc.) will invade through the weak part of the coating, causing corrosion under the film, and then the coating will blister and peel off.

In addition, even with the same coating thickness, the secondary coating is denser than the primary coating. According to foreign reports and related corrosion test results, the front coating more than 20 μm can effectively prevent the invasion of corrosion medium, due to the different corrosion prevention mechanism of primer and topcoat, not only to specify the total film thickness, but also the thickness of the primer (≥ 5 μm) and topcoat (≥ 15 μm), only in this way can ensure that the corrosion resistance of different parts of the prepainted steel plate is balanced.

PVDF products require thicker coatings because they are guaranteed to last a long life. The requirements for the back coating depend on the use, sandwich panels only require a layer of adhesive primer, while formed steel plates also require two layers due to indoor corrosion environment, with a thickness of at least 10μm or more.

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