Washing
Pre-treatment and Washing
The heat galvanized pieces are washed with a phosphorous-based cleaning agent at 50°C. This is followed by two rinses with demineralized water and a final zinc passivation phase. The wash cycle lasts approximately 45 minutes out of a total 3-hour painting cycle.
It must be pointed out that, for any other type of ferrous material, besides the phosphorous-based cleaning, there is also a phosphorous-based degreasing step, again performed at 50°C. Both these steps serve to better remove any grease from the pieces, thus improving application of the paint powder and guaranteeing that it holds.
Feautures
- complete removal of oxides (white rust)
- removal of the GAMMA T surface layer of the steel-zinc alloy, up to a thickness of 0.5-1 μ (micron)
- surface pickling to increase the hold and roughness of the surface
- formation of a complex, zinc phosphate surface layer that also offers temporary protection against FLASH RUSTING
- complete dissolution of the removed zinc in the bath
- non-chrome passivation of the surface to enhance anticorrosive hold
- final wash with demineralized water having a low µS (microsiemens) value, thus ensuring that all salts are total dissolved
- chemical control of the process parameters to achieve standard operating values
- low environmental impact, all non-toxic products
From what is described, the objectives reached can be summarized as follows:
- adhesion
- corrosion-proofing
- easy use
- broad conversion range
- ability to apply with finishing coat and/or cataphoretic base coat
