Pre-treatment

Pre-treating any item that requires powder coating is an extremely important aspect to powder coating. Powder coating is just like painting in one important respect - if the surface being powder coated is not prepared properly, the coating won't last.

This is particularly true for exterior items prone to rusting and corroding in the harsh New Zealand environment. Both salt and high-UV sun can wreak havoc with coatings. Improperly treated steel, for instance, rusts very quickly and without proper pre-treatment will last only four months but correctly powder coated, will last approximately 20-30 years.
Metal must be prepared carefully and an anti-corrosive applied. This allows the powder to adhere properly, otherwise it simply falls off. How a product is pre-treated depends on what it is and what it will be used for. A complete pre-treatment process consists of cleaning, rinsing, conversion coating, seal rinsing, drying and cooling.


At Rainbow Powder Coaters, steel is pre-treated with iron phosphate. Aluminium undergoes a chromate conversion coating. Hot dipped galvanised items and electro-galvanised items are also sent through our chromate conversion tanks.