Coating Terms

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Description
The first pigmented layer of a multi-layer coating system.
Primers applied as a thin layer to promote interlaminar adhesion on surfaces difficult to adhere. The surfaces difficult to adhere are mainly polyolefinic structured plastic surfaces like polyethylene and polypropylene etc. and some aluminium alloy surfaces. Examples of adhesion promoters are chlorinated polyolefin, organosilanes and polyvinylbutyral based primers.
Anti corrosive primer applied on ferrous or light alloy surfaces at 4-7 mm dry film thickness. Since first applications were done by washing the object with the primer, they are called “wash primers”. Wash primers are formulated with polyvinylbutyral as well as epoxy and phenolic resins. In the last two decades, wash primers included zinc phosphate pigments instead of zinc chromates due to hazards caused by Cr+6 to the environment and human health. Wash primers are catalyzed with acid-catalysts for a good adhesion on the metal surface. Applying layers with basic resins on the wash primer films with acid molecules left inside may result in intercoat adhesion failure. Therefore, attention should be paid to wash primer application.