Powder coating is a process that starts off with a very fine powder containing particles which, when exposed to high levels of heat, melt, run together and reveal their colour. The process that the metal undergoes is quite complex, but it is necessary in order to prepare the metal properly in order to gain the familiar highly uniform, drip-free, shiny finish associated with a high-quality coating.
Depending on where an item is going to be placed applying a powder coating can potentially reduce the overall maintenance costs of the item over its lifetime, however it should be noted that because organic compounds are used within the coloured powders that reactions and degradation of the coating are possible over much shorter timescales. One of the main areas where this occurs is in marine environments due to the salt water.
In order to get something powder coated it must first be dismantled into its constituent parts and then transported to a dedicated coating facility. Structures cannot be coated in situ because of the technical requirements of the coating process. The quality of a coating is partly dependent on the type of metal being coated and the way it has been finished, but in general the main limiting factor of what can be coated is the size of the item. There are many facilities that can cater for small items, but there are also dedicated larger processing plants that are able to coat even very large metal items.
When an item arrives at the coating plant they are process and the material and finish are checked before the items are then booked onto the production line. Once items are in place and start to move through the production line they will remain in a clean environment in order to ensure the best finish possible is given.
Items begin with a pre-treatment in which they are cleaned thoroughly to remove both dirt and any residual grease from loading and manufacturing processes. This cleaning process ensures that the powder coating will have a very uniform covering of the item and the adhesion will not be affected by any particles of grease or dirt getting in the way. Another thing that can affect adhesion is water. Therefore the next stage of the process is to pass the items through a drying room, which will remove all traces of moisture from the surface of the item to be coated.
The metal is then given an electrostatic charge, which attracts the particles from the air and makes them stick to the metal surface. By coating an item in this manner it is possible to ensure a very uniform, and thin, coating. The final stage is to cure the powder by heating it in an oven until it becomes molten. After cooling the items then go through an inspection process to ensure that the coating has been carried out to the correct standards. Only once these inspections have been passed satisfactorily will the items then be packaged and sent on to be assembled or installed.
