Wrought iron offers a graceful and enduring material for many types of outdoor structures. Unfortunately, iron develops rust when exposed to moisture, which can degrade the metal and cause unsightly discoloration and even destruction of the metal components. Before repainting your wrought iron gazebo, you must remove all traces of rusting and apply chemical inhibitors to prevent further deterioration.
About Rust On Metal
Not all metals rust, but iron and steel does rust, and this occurs through a chemical reaction on the surface of iron that is contact with atmospheric moisture such as rainfall, lawn sprinklers and humidity. The water molecules break the bonds of the metal molecules and instead form oxide compounds that are the orange-red discoloration on iron. Unless prevented, this reaction continues into the interior of the metal until it disintegrates in areas weakening the entire structure. The presence of salt spray, as in coastal areas, can greatly increase the amount of rusting, according to the University of Hawaii website.
Before attempting to re-finish metal surfaces, such as a wrought iron gazebo, all traces of rust must be removed. A variety of methods are used to remove rust. Simple sandpaper or electric sanding equipment does a good job of removing rust from small, manageable areas. A metal file is often used to file off heavily rusted areas. Sandblasting is also used to remove rust from metal surfaces. In sandblasting, a “media” such as sand, glass beads, aluminum oxide or other materials are shot across the surface of the metal at high speeds. This process removes old paint and other coatings as well as built-up rust deposits. Once the bare metal is exposed, other methods are used to prepare the surface to hold the new paint.
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Surface Preparation Before Painting
Once the surface rust is completely removed, metal surfaces are painted with rust-converting compounds such as phosphoric acid. This compound removes corrosion and converts any residue to iron phosphate. This stays behind on the material as a protective coating for the metal, according to writer Bob Neidorff at the MetalWebNews.
Next, a metal primer is applied to the wrought iron gazebo. Metal primers contain rust-inhibiting chemicals that help to prevent further rust development. You should always use a high-quality rust-inhibiting primer for iron or steel outdoor structures. Finally, paint the surface of the wrought iron with a good quality metal paint. Allow the first coat to dry thoroughly before applying the second coat. Powder coating is another method used to finish metal. The process uses paint pigment and a resin that is applied electrostatically and then baked at high temperatures to produce a tough, long-lasting finish on metal. This method generally requires dismantling the structure and taking it in to a powder coating shop for finishing.