Apart from cleaning, several
other pretreatments exist to enhance adhesion of the paint to the substrate:
- Flaming is a simple and widely used process, in which a gas flame is moved a
few centimeters above the surface of the part. The speed with which the flame
is moved is in the order of 0.1 m/sec. Propane, butane and natural gas can be
used to fuel the flame.
- Low pressure plasma treatment is specially
suited for complex parts, with surfaces that cannot easily be reached in flame
or corona treatments. In this batch process, the parts are exposed to gas
discharge at low pressure.
- Corona treatment is an electrical
discharge process. A high voltage, high frequency electrode is moved over the
surface of the part at a distance of 1 to 2 mm, activating the surface through
oxidation and ozone formation. This process is normally used for parts with
flat surfaces and is specially suitable for sheet material.