The pre-treatment step of the powder coating process is one of the most important. It is never skimped on and high-quality companies never cut corners to try to save money or time. Without following the steps to ensure that the pre-treatment portion of the process is performed correctly, some parts of the metal’s surface could remain unprepared. This, in turn, would negatively affect the smooth and cohesive adherence of the powder coating process.
Even though steel has a reputation for being strong, it is not without its vulnerabilities. Steel, when exposed to the right combination of elements and materials, can become structurally unsound. Pre-treatment adequately prepares the surface of the steel so that the powder coating adheres as intended. Zinc phosphate and iron phosphate are two of the most common pre-treatment formulations. At the heart of phosphate pre-treatment is the cleaning process that rids the material of any oil, dirt, grime or debris that could mar the ability of the paint to stick seamlessly to the metal.
Removing any unwanted particles that might be clinging to the metal is only the first step in the pre-treatment phase. This is followed by a coating of an inorganic material — either zinc or iron. Both iron and zinc make the metal’s surface smooth and inert, prepares it to bond with powder coating and protects it from rust and other corrosives.
Advantages of Using Zinc Over Iron
When the two chemicals are compared side-by-side, zinc phosphate is more reliable and it lasts longer.
- Without the need for a sealer, zinc phosphate can protect raw steel from harmful sea spray for 750 hours. Galvanized steel is protected for upwards of 1,000 hours when zinc phosphate is used.
- The pre-treatment of mixed metals is a seamless process when using zinc phosphate. Unlike iron phosphate that requires the use of a modification that contains fluoride, zinc phosphate can be used as is when treating mixed metals. In some cases, though, fluoride or calcium is used to strengthening the mixture.
- Pre-treatment solutions that use zinc phosphate produce their own coating. This coating helps the zinc phosphate cling more effectively to the metal’s surface. Crystals from the coating form on its surface. They continue this process until they make contact with other crystals. This helps ensure even coverage, particularly within those areas that are recessed.
Production Paint Finishers constantly seeks to improve its processes, such as pre-treatment, in an effort to always ensure that their clients have the best products and results. Request a quote for their services here.