Pretreatment

These Pretreatment is a process in which the surface of the component to be painted is chemically cleaned and prepared for the painting operation. Metallic components can be freed from impurities with proper Pretreatment, using degreasing and derusting solutions, coated with a protective layer of phosphates and passivated for lasting effects.
The process of pre treatment can be broken up into the following stages in Powder Coating System :-
1. DEGREASING IN PRE TREATMENT : In this stage, the component is freed of grease, oil and other unwanted contaminants like dirt and swart adhering to its surface.
2. WATER RINSE : Whenever components are degreased by using alkali, they should be rinsed, preferably twice, to remove all traces of alkali which may have remained on the components.
3. PRE TREATMENT FOR PICKLING OR DERUSTING : In this process, rust and scales are removed from the component by means of acid solution.
4. WATER RINSE : The above operation is followed by one or two water rinses to remove all traces of acid.
5. PRE TREATMENT IN PHOSPHATING / CHROMATISING In this operation, the clean surface of the component is coated with a thin layer of phosphate or chromate salt by using a phosphating / chromatising solution.
6. PRE TREATMENTS IN WATER RINSE :The above operation is followed by one or two water rinses.