Definition - What does Wash Primer mean?
A wash primer is a synthetic primer that usually contains zinc chromate or phosphoric acid. It is used as a first coat on metal surfaces and has anticorrosion properties, making it a prerequisite or pretreatment before any coating application.
A wash primer makes the painting process more efficient and imparts optimal corrosion resistance to materials such as steel aluminum and galvanized parts. It is specially designed to work in conjunction with all types of coatings to provide maximum protection against corrosion and any form of damage.
Corrosionpedia explains Wash Primer
Wash primers are typically applied on galvanized, aluminum parts and can be used along with primers that are rich in zinc. Wash primers in general are recommended for a variety of substrates such as:
- Stainless steel
- Primers rich in zinc
Most wash primers are fast drying and can offer early resistance to rust. They also involve no crucial film thickness and feature low odor and unlimited recoat time. It must be noted that wash primers are not applicable to plastic or wooden surfaces.
In order to apply wash primers, the following surface preparation methods should be followed:
- The surface should be thoroughly degreased and cleaned. The use of pressure washers, steam cleaners and commercial detergents is a must. The surface must be free from detergent residues. It is recommended to use a wiping solvent for the final wipe down.
- Objects such as stainless steel and anodized parts should be sanded to loosen the anodized portion and promote adhesion of the wash primer.
- For anodized aluminum of architectural grade, the surface should be sanded using 40-80 grit sandpaper until the profile of the surface can be seen. Then, the surface should be degreased and cleaned thoroughly.
In mixing wash primers, it is necessary to mix the base thoroughly until a homogeneous and consistent blend is achieved. Most industries make use of shakers and power mixers, but hand mixing is also acceptable. Once mixed, the converter is added and then mixed again to achieve the right blend and consistency. The most common method to apply a wash primer is through an air atomized spray.