Why can’t rust-primer coatings be used on metal surfaces for a long time, and why do short-term coatings experience re-rusting, peeling, and other issues?
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Why can’t rust-primer coatings be used on metal surfaces for a long time, and why do short-term coatings experience re-rusting, peeling, and other issues? We know that the rust-primer is applied directly to the corroded metal surface. Its feature is its ability to convert heavy rust, with a fast conversion rate. Some can be used directly as a primer in combination with other topcoats. However, such primers have a short service life; in about half a year or a year, problems may arise with the coating, such as rusting on the surface of the coating, delamination, and peeling. What are the reasons for these problems?
Although rust-primer can rapidly convert rust and be applied directly to rusty metal surfaces, it actually cannot penetrate completely into the metal substrate, and thus it is unable to completely remove or stabilize all rust deposits. Since primers have only a limited ability to prevent rust, over time, the unconverted or incompletely stabilized rust areas beneath the metal continue to develop, leading to new rust formation. This, in turn, affects the adhesion of the coating and causes problems such as re-rusting, peeling, and flaking. Therefore, rust-primer is more suitable for short-term protection or temporary repairs, rather than long-term use. .